Dissertations / Theses on the topic 'Sorbent material'

The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).

The process of surface modification allows us to combine the structural advantages of materials with the chemical functionality of organic compounds. Attachment of functional organic molecules to surfaces of high surface area substrates yields materials having dense chemical functionality. Materials with meso- and nanoscale features are often used as support substrates because their small-scale features provide very high surface area. Mesoporous silica is one of the most chemically accessible mesoscale materials, and the well-established chemistries of its production and modification lead to controlled pore structure and rapid kinetics. Such materials have seen use as sorbents for environmental remediation of contaminated water. For this application, their high degree of functionality and high-affinity surface chemistries permit a relatively small amount of material to effectively treat a large volume of water. The many advantages of these highly engineered materials come at a relatively high economic cost. The high-affinity chemical functionalities that provide these materials with unprecedented efficiencies also make them correspondingly more difficult to recycle. One-time utilization of these materials makes the cost-per-use high which consequently limits their economically viable applications. The goal of this work has been to explore surface chemistries that will allow high performance, regenerable or recyclable sorbent materials. Shifting from a single-use material to a regenerable platform in which the mesoscale supports are recycled may lower the environmental and economic costs of the material while retaining the advantageous properties of the meso- and nanostructured materials. We chose to approach this goal by developing non-covalent, supramolecular surface modification techniques as alternatives to current surface modification techniques which, almost without exception, are based on covalent modification motifs. Non-covalent attachment of organic molecules to surfaces allows us to avoid the necessity of optimizing the attachment for each class of organic molecule as well as avoid protection and de-protection procedures necessary to attach delicate or reactive functional groups to surfaces. In this way, supramolecular modification processes reduce the cost of material research and development in addition to the costs of material production and use. The process of surface modification allows us to combine the structural advantages of materials with the chemical functionality of organic compounds. Attachment of functional organic molecules to surfaces of high surface area substrates yields materials having dense chemical functionality. Materials with meso- and nanoscale features are often used as support substrates because their small-scale features provide very high surface area. Mesoporous silica is one of the most chemically accessible mesoscale materials, and the well-established chemistries of its production and modification lead to controlled pore structure and rapid kinetics. Such materials have seen use as sorbents for environmental remediation of contaminated water. For this application, their high degree of functionality and high-affinity surface chemistries permit a relatively small amount of material to effectively treat a large volume of water. The many advantages of these highly engineered materials come at a relatively high economic cost. The high-affinity chemical functionalities that provide these materials with unprecedented efficiencies also make them correspondingly more difficult to recycle. One-time utilization of these materials makes the cost-per-use high which consequently limits their economically viable applications. The goal of this work has been to explore surface chemistries that will allow high performance, regenerable or recyclable sorbent materials. Shifting from a single-use material to a regenerable platform in which the mesoscale supports are recycled may lower the environmental and economic costs of the material while retaining the advantageous properties of the meso- and nanostructured materials. We chose to approach this goal by developing non-covalent, supramolecular surface modification techniques as alternatives to current surface modification techniques which, almost without exception, are based on covalent modification motifs. Non-covalent attachment of organic molecules to surfaces allows us to avoid the necessity of optimizing the attachment for each class of organic molecule as well as avoid protection and de-protection procedures necessary to attach delicate or reactive functional groups to surfaces. In this way, supramolecular modification processes reduce the cost of material research and development in addition to the costs of material production and use. This dissertation contains previously published and unpublished co-authored material.

Les matériaux de construction sorptifs comme solution de remédiation à la pollution des environnements intérieurs semblent être une alternative prometteuse aux solutions conventionnelles d’assainissement de l’air, auxquelles sont reprochées une consommation d'énergie importante et la potentielle libération de sous-produits nocifs. Dans ce travail de thèse, les propriétés d’élimination des polluants de plaques de plâtre et d’enduits à base de chaux enrichis en Charbons Actifs (CA), comme sorbants, sont étudiées. Trois réacteurs à différentes échelles sont déployés pour évaluer de manière complémentaire le comportement des matériaux vis-à-vis des Composés Organiques Volatiles (COV) typiques des environnements intérieurs. Les capacités de piégeage des sorbants en poudre sont caractérisées en les exposant à des COV individuels (toluène ou formaldéhyde) dans un réacteur en U en conditions ambiantes (50 % RH à 23 °C). Leur morphologie et chimie de surface sont étudiées et corrélées aux propriétés de piégeage. De plus, le devenir des COV adsorbés est étudié à température ambiante, et selon un scénario d’élévation de température typique d’un environnement intérieur. Les résultats obtenus pour cette échelle expérimentale aboutissent à des recommandations pour la sélection de charbons actifs. Des échantillons de matériaux de construction mis en œuvre, exposés à un mélange de 18 COV représentatifs de la diversité des polluants intérieurs, sont étudiés à l'aide d'un réacteur FLEC. Les capacités de piégeage des matériaux de construction enrichis en CA sont évaluées en les exposant de manière continue pendant 42 jours au mélange de COV. Des paramètres clés sont proposés pour discriminer l’impact des matériaux sur la qualité de l’air intérieur (QAI). L'introduction de charbon actif améliore remarquablement la capacité des matériaux de construction à éliminer les COV à court et à long terme. De plus, des expériences dédiées au formaldéhyde mettent en évidence une adsorption réactive sur la matrice « enduit à base de chaux » : la réaction de Cannizzaro conduit à la formation de méthanol gazeux et de formiates adsorbés. A échelle réelle, à l’aide de la pièce expérimentale IRINA de 40 m3, la matrice « enduit à base de chaux » et un enduit enrichi en CA sont exposés à des polluants sélectionnés (ozone, toluène, décane, limonène, acétone, éthanol et formaldéhyde) à des niveaux typiques de l’air intérieur. L'efficacité du plâtre enrichi en charbon actif pour atténuer les épisodes de pollution est démontrée et quantifiée pour tous les composés étudiés. Les résultats à échelle réelle soulignent que les matériaux de construction sorptifs peuvent être appliqués au même titre que des dispositifs actifs et oxydatifs de traitement de l'air, largement déployés à l’heure actuelle
Use of sorptive construction materials to mitigate VOC concentrations indoors appears as a promising alternative to conventional solutions responsible for energy consumption and potential harmful by-products release. In this PhD, the VOC uptake properties of gypsum boards and lime-cement plasters enriched in VOC sorbents, activated carbons (AC), are investigated. Three-scale reactors have been deployed to complementarily assess the behavior of the materials regarding indoor Volatiles Organic Compounds (VOCs). Selected powder sorbents, exposed to single VOC (toluene and formaldehyde), are characterized using a U-shape reactor under mild conditions (50% RH and 23 °C). AC surface chemistry and morphology are correlated with VOC uptake capacities. The fate of taken up VOCs on AC surface is investigated at ambient temperature and under typical indoor heat events. Results lead to the definition of guidelines for AC selection. Fully processed board samples, exposed to an 18-VOC mix, representative of indoor pollutant diversity, are studied using FLEC reactors. The uptake capacities of sorptive materials are assessed using a continuous 42-day exposure to the VOC mix. Key parameters are proposed to discriminate materials according to their impact on IAQ. The introduction of ACs remarkably enhances the VOC removal ability of construction materials on short and long term. Additionally, experiments dedicated to HCHO evidence a reactive uptake on lime-cement plaster matrix: Cannizzaro reaction leads to the formation of gaseous methanol and adsorbed formates. At real scale, using the 40-m3 IRINA experimental room, lime-cement plaster matrix and a lime-cement plaster enriched in AC are exposed to selected pollutants (ozone, toluene, decane, limonene, acetone, ethanol and formaldehyde) at typical indoor level. The effectiveness of the AC-enriched plaster to mitigate pollution episodes is evidenced and quantified for all investigated compounds. Real scale results emphasize that sorptive construction materials can perform as well as widespread active and oxidative air treatment devices

The development of the mining industry has led to an increase in the environmental impacts generated by the industry. Mining influenced waters have a severe impact over the surrounding aquatic environment as the waters may contain pollutants in dissolved and particulate form, such as heavy metals and metalloids. The severity of these impacts is dependent on, among other factors, the hydrological characteristics of the receiving water bodies as well as the mine water composition. Among the numerous methods that have been developed for mining water purification, adsorption via biosorbents has proven to be an effective and sustainable option. A number of biosorbent materials have been extensively studied for their metal adsorption capacity such as bark, seaweed, modified cotton, lignin, and peat, among others. In Finland, peat is of interest because it is widely available. Although natural peat has been found to possess high sorption capacity for metal and metalloids, a variety of treatments (physical, chemical, etc.) have also been investigated aiming to increase sorption capacity or to modify chemical and/or physical properties that can improve its application as a sorbent. It is important to note that although several studies have reported on the sorption capacity of natural and modified peat, these studies have been mostly conducted in a laboratory scale and used synthetic water samples. Only a small number of purification systems using peat as a biosorbent have been reported in pilot-scale or full-scale scenarios. There is therefore a lack of knowledge regarding the suitability of peat as a biosorbent for metal removal from real water samples containing a mix of contaminants. Furthermore, there is a need for reports describing the performance of peat in pilot systems simulating real applications. The main objective of this thesis was thus to evaluate the suitability of using peat as a sorbent for the purification of mine process and drainage waters in two pilot-scale purification systems. Another objective was to evaluate the effect of the systems design parameters over metal removal and use the obtained results to conclude on the viability for full-scale applications. For this purpose, a mix-and-settling system and a horizontal filter system were tested using natural and chemically modified peat as sorbents and real drainage water was collected from a mining site in Northern Finland. A factorial design was used in the planning of experiments to evaluate the effect of operational factors (sorbent type, dose, mixing intensity and mixing time) in a mix-and-settling system. The purification efficiencies achieved in the system showed removal efficiencies as high as 80% for Ni and 68% for As, when a high dosage of natural peat was combined with high levels of mixing time and mixing intensity. Further statistical analysis showed that sorbent dose was the most influential factor affecting purification efficiency. Two small-scale horizontal filters were built (three compartments, sand-peat-sand) to evaluate the suitability of natural and modified peat as sorbent agents in such systems. High removal rates of selected metals was achieved, e.g., Ni with 98% and 96% of removal in the modified and natural peat filters respectively and As 87% removal by the natural peat filter. Removal efficiency at the end of test period was still satisfactory although it decrease treated water volume in both pilots (20–30%). Low hydraulic conductivity of peat makes the scaling-up of the filter system to a full- scale application non-viable, as the required retention times would be excessively high for this purpose. Overall peat proved to maintain its adsorption properties when applied to pilot-scale systems, with the mix-and-settling system showing to be a promising technology for the purification of mine influenced waters. Nevertheless, concerns such as the improper mixing of peat in the system and poor settling of particles need to be solved before full-scale application can become a reality.

Arsenic (As) contamination is a worldwide problem, and millions of people are suffering from it. There are two major inorganic forms of As in waters: arsenate(V) and arsenite(III), and adsorption to a sorbent material may be an efficient method to handle them. In this study, we focused on As(III), the more toxic form, which predominates under reducing conditions. The As(III) removal properties of four sorbent materials: hydrotalcite, Mg−Al layered double hydroxide, amorphous aluminium hydroxide and amorphous titanium oxide, are examined from the following viewpoints: As(III) adsorption, the effects of pH, the effects of adsorbent concentration, adsorption as a function of dissolved As(III), and the effect of co-existing anions (HCO3− and PO43−). The maximum adsorption of As(III) to HT (0.1 mmol As(III)/g adsorbent), Mg-Al LDH (0.1 mmol As(III)/g adsorbent), am-Al(OH)3 (0.22 mmol As(III)/g adsorbent), and am-TiO2 (0.21 mmol As(III)/g adsorbent) occurred at pH 7.5, 7, 7, 8, respectively. At this pH, approximately 20%, 62%, 35%, and 98.3%, respectively, of the added As(III) was adsorbed. When the As(III) to sorbent ratio was increased, the adsorption was instead around 7% to am-Al(OH)3 (2.2 mmol As(III)/g adsorbent), and 46.3% to am-TiO2 (2.1 mmol As(III)/g adsorbent). These figures show that am-TiO2is the most efficient sorbent for As(III) adsorption of the four materials tested, Mg-Al LDH is second best, while HT and am-Al(OH)3 are not suitable for As(III) removal. The adsorption of As(III) to Mg-Al LDH as a function of dissolved As(III) could be adequately described by a linear equation, suggesting that As(III) adsorption to Mg-Al LDH was governed by anion exchange. As a result, the co-existing anions (HCO3- and PO43-) showed a significant influence on As(III) adsorption to Mg-Al LDH. Considering the interfering effects of co-existing anions on am-TiO2, HCO3− did not influence As(III) adsorption, while PO43- caused a slight but clear competition effect. Overall, am-TiO2 would be the best choice of these four materials in contact with As-contaminated groundwater due to its superior As(III) removal properties and the limited competition from co-existing anions on As(III) adsorption.
Alltför höga halter av arsenik (As) i vatten är ett världsomspännande problem som orsakar hälsoproblem för miljontals människor. Det finns två huvudsakliga oorganiska former av As i vatten: arsenat(V) och arsenit(III), och adsorption till ett material (s.k. ”sorbent”) kan vara eneffektiv metod för att avlägsna dem från vatten. I denna studie fokuserade vi på arsenit(III), den mer giftiga formen, vilken dominerar under reducerande förhållanden. Vi undersökte adsorptionsegenskaperna för arsenit(III) för fyra sorbentmaterial som kan vara tänkbara när det gäller arsenikrening av förorenade vatten: hydrotalkit, s.k. Mg-Al LDH (Mg-Al-skiktad dubbelhydroxid), am-Al(OH)3 (amorf aluminiumhydroxid), och am-TiO2 (amorf titandioxid). Dessa material undersöktes när det gäller följande: adsorption av arsenit(III) som funktion av pH,betydelsen av sorbentkoncentration, adsorption som funktion av löst arsenit(III) (”isoterm”), och konkurrens från samexisterande anjoner (HCO3− och PO43−). Den maximala adsorptionen av As (III) till HT (0,1 mmol As(III)/g sorbent), Mg-Al LDH (0,1 mmol As(III)/g sorbent), am-Al(OH)3 (0,22 mmol As(III)/g sorbent) och am-TiO2(0,21 mmol As(III)/g sorbent) inträffade vid pH 7,5, 7, 7, respektive 8. Vid dessa pH-värden adsorberades ungefär 20%, 62%, 35% respektive 98,3% tillsatt As(III). När kvoten mellan As(III) till sorbent ökades blev adsorptionen istället cirka 7% till am-Al(OH)3 (2,2 mmol As(III)/g sorbent) och 46,3% till am-Ti02(2,1mmol As(III)/g sorbent). Dock var adsorptionsmängden per viktsenhetsorbenthögre över hela pH-området. Dessa siffror visar att am-TiO2 är det mest effektiva av de fyra testade materialen för As(III)-adsorption, Mg-Al LDH det näst bästa, medan HT och am-Al(OH)3 är olämpliga för detta ändamål. Adsorptionen av As(III) till Mg-Al LDH som funktion av löst As(III) kunde beskrivas väl med en linjär ekvation, vilket antyder att adsorptionen av As(III) till Mg-Al LDH styrdes av anjonbyte. I konsekvens med detta hade de samexisterande anjonerna (HCO3- och PO43-) ett betydande inflytande på As(III)-adsorptionen till Mg-Al LDH. För am-TiO2 påverkade HCO3− inte As(III)-adsorptionen, medan PO43- orsakade en liten men tydlig konkurrenseffekt. Sammantaget är am-TiO2 det bästa valet av dessa fyra material i kontakt med As- kontaminerat grundvatten på grund av dess betydligt bättre förmåga att avskilja arsenit(III) och den förhållandevis blygsamma konkurrensen från andra anjoner.

A wide range of organic compounds are released from building and furnishing products and these have the potential to adversely affect indoor air quality. There are growing international requirements for testing and controlling these emissions for the protection of public health. The test methods require specialist analytical chemistry facilities based on thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). This project has addressed the need for better performance and greater automation of the analysis, as well as development of simpler screening tests. A variety of products were tested using screening techniques, with an emission cell method being used as a reference test. Short duration tests, using a micro-scale chamber at slightly elevated temperature, were shown to have the potential to predict emissions occurring during longer term reference tests. Multi-sorbent air sampling tubes, that have the potential to extend the volatility range of compounds determined by a single TD/GC/MS analysis, were compared with Tenax TA tubes specified by current standard methods. This showed no difference in performance for the range of compounds for which Tenax is optimal, with improved performance for a number of more volatile compounds. The determination of formaldehyde was investigated using 2-hydroxymethylpiperidine as a derivatising agent, followed by TD/GC/MS. The results showed the possibility of this method being developed as an alternative to the current standard method that involves solvent elution and liquid chromatography. The performance of a newly developed time-of-flight mass spectrometer was compared with a standard quadrupole instrument. This showed its potential, with the use of re-collection, to extend the concentration range of compounds quantified from a single air sample, of particular benefit for the determination of carcinogens. New compound identification software was applied to increase automation of analysis of the TD/GC/MS data. Good correlation with manual processing was achieved, demonstrating the possibility of routine application to material emissions testing.

Hydrocarbon spills on roads are a major safety concern for the driving public and can have severe cost impacts both on pavement maintenance and to the economy through disruption to services. The time taken to clean-up spills and re-open roads in a safe driving condition is an issue of increasing concern given traffic levels on major urban arterials. Thus, the primary aim of the research was to develop a sorbent material that facilitates rapid clean-up of road spills. The methodology involved extensive research into a range of materials (organic, inorganic and synthetic sorbents), comprehensive testing in the laboratory, scale-up and field, and product design (i.e. concept to prototype). The study also applied chemometrics to provide consistent, comparative methods of sorbent evaluation and performance. In addition, sorbent materials at every stage were compared against a commercial benchmark. For the first time, the impact of diesel on asphalt pavement has been quantified and assessed in a systematic way. Contrary to conventional thinking and anecdotal observations, the study determined that the action of diesel on asphalt was quite rapid (i.e. hours rather than weeks or months). This significant finding demonstrates the need to minimise the impact of hydrocarbon spills and the potential application of the sorbent option. To better understand the adsorption phenomenon, surface characterisation techniques were applied to selected sorbent materials (i.e. sand, organo-clay and cotton fibre). Brunauer Emmett Teller (BET) and thermal analysis indicated that the main adsorption mechanism for the sorbents occurred on the external surface of the material in the diffusion region (sand and organo-clay) and/or capillaries (cotton fibre). Using environmental scanning electron microscopy (ESEM), it was observed that adsorption by the interfibre capillaries contributed to the high uptake of hydrocarbons by the cotton fibre. Understanding the adsorption mechanism for these sorbents provided some guidance and scientific basis for the selection of materials. The study determined that non-woven cotton mats were ideal sorbent materials for clean-up of hydrocarbon spills. The prototype sorbent was found to perform significantly better than the commercial benchmark, displaying the following key properties: • superior hydrocarbon pick-up from the road pavement; • high hydrocarbon retention capacity under an applied load; • adequate field skid resistance post treatment; • functional and easy to use in the field (e.g. routine handling, transportation, application and recovery); • relatively inexpensive to produce due to the use of raw cotton fibre and simple production process; • environmentally friendly (e.g. renewable materials, non-toxic to environment and operators, and biodegradable); and • rapid response time (e.g. two minutes total clean-up time compared with thirty minutes for reference sorbents). The major outcomes of the research project include: a) development of a specifically designed sorbent material suitable for cleaning up hydrocarbon spills on roads; b) submission of patent application (serial number AU2005905850) for the prototype product; and c) preparation of Commercialisation Strategy to advance the sorbent product to the next phase (i.e. R&D to product commercialisation).

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.
Includes bibliographical references (leaf 36).
Cryptomelane-type Manganese oxide (OMS-2, a group of Octahedral Molecular Sieves) nanowire paper exhibits interesting properties: reversible wettability, oleophilic while being hydrophobic, and high thermal stability. These properties open up possible markets for commercialization. This thesis reviews the market potential of each of these properties and explores the competitiveness of the nanowire paper in the proposed markets. The proposed values of this technology are in its high selective absorbency towards oil, high performance over cost metric and its high thermal stability. Its thermal stability enables a thermal desorption type process to regenerate and recycle the sorbent for reuse. This translates into further differentiation and provides greater value for the users.
by Haw Yun Soo.
M.Eng.

The enormous anthropogenic emission of carbon dioxide is most likely one of the main reasons for the global warming and the climate change problems ([1], [2], [3]). Considering the continuing and progressively growing utilization of fossil fuels, mainly in the power generation sector where fossil fuel-based combustion and gasification power plants are predominant, the development and implementation of processes that avoid the associated CO2 emissions must be urgently identified. Carbon dioxide capture and storage, commonly termed CCS, represents a range of technologies oriented to affordably and efficiently sequester carbon dioxide from these sources and would be a possible mid-term solution to mitigate the emissions of CO2 into the atmosphere ([4]). However, the costs (especially in terms of penalties in the power plants efficiency) associated with the current industrially available CO2 capture techniques, such as amine-based scrubbing, are prohibitively high, thus making the development of new CO2 sorbents an highly important research challenge. Among several strategies currently under investigation, calcium oxide (CaO), readily obtained through a calcination stage of naturally occurring calcium carbonate (CaCO3), has been proposed as an alternative CO2 solid sorbent that could significantly reduce the costs of carbon dioxide capture systems. The technique, widely discussed in the literature and recently reviewed by several authors ([5], [6], [7] and [8]), is based on the reversible reaction CaO (s) + CO2 (g) ↔ CaCO3 (s) and is applied through cyclic stages of carbonation and of calcination, offering a number of advantages. However, a few issues, including especially the decline of sorbent capacity when they are cycled through multiple CO2 capture-and release stages, still call into question its widespread deployment on industrial applications. The improvement of this technology and the development of new calcium-based solid sorbents are currently a matter of study and, despite the apparent simplicity of the chemistry involved, several aspects of the carbonation reaction and its kinetics are still not clearly understood. The determination of the surface reaction kinetic parameters is one of the open disputes. Several contributions investigating the carbonation reaction and its kinetics have reported thus far activation energies varying in a range of about 20 ÷ 30 kJ/mol ([9], [10]) and 70 ÷ 80 kJ/mol ([11], [12], [13], [14]); a few authors otherwise asserted that the carbonation reaction has a zero-activation energy ([15], [16]). These values were estimated from CaO conversion versus time profiles obtained from CO2 absorption analysis carried out in a wide range of operating conditions in terms of carbonation temperatures and CO2 partial pressures and hence, the observed uncertainty in the mentioned activation energies is reasonably related to the quality of the experimental data. The accuracy of the experimental data is a questionable matter especially when the data are obtained through the thermo-gravimetric approach because, as well known, TGA experiments are typically affected by mass transfer limitations. The external diffusion is particularly important because it weighs on the gas (CO2) diffusion towards the solid sorbent (CaO) surface that is essential to support the carbon dioxide mole consumption due to the chemical reaction. Even though several strategies can be applied to reduce the external mass diffusion during the CaO carbonation studied in a TGA system (typically increasing the gas flow rates), evidences of a complete removal of such resistance cannot be easily provided. In fact, the typical circumstance that at high gas flow rates the conversion versus time curves can show no changes when increasing the gas flow rate does not imply that the external mass diffusion resistance is eliminated, but only that such resistance cannot be further reduced in the TGA geometry and operating conditions used. Indeed, the local velocities reached around/inside a TGA crucible (especially above the sorbent particles contained in a common sample holder) could be low even when the average velocity in the furnace is increased by increasing the gas flow rate, so that the local velocities around/inside a TGA crucible cannot be increased enough to compensate the very high consumption rate of CO2 due to the fast carbonation surface reaction. Therefore, alternative method has to be studied in order to measure CaO conversion versus time profile actually not limited by the external mass diffusion, and to check the validity of the thermo-gravimetric data currently available. A second aspect concerns the structural properties characterizing the solid sorbent particles and how such properties can affect the CO2 absorption performances of CaO. Since, CaO-CO2 is a typical gas-solid reaction, it is most likely that specific surface and pore volume distribution can affect the reaction kinetics of CaO sorbent particles, as well as their absorption capacity. Several studies have been carried out to comprehend the carbonation reaction and kinetics in terms of these structural properties (porosity, specific surface, structural parameter, or the whole pore size distribution) through the development and application of random pore/grain models ([15], [17], [10], [13], [18], [19]). Most of these contributions related the transition from the fast regime to the slow product-layer diffusion controlled regime, characterizing the CaO carbonation, to the filling of small pores and/or to the development of a critical carbonate layer, and focused the attention on the impact of the pore size distribution on the critical CaCO3 product layer thickness, for which an unambiguous value or a direct measure has not been anyway proposed. Additionally, even though CaO and CaCO3 are crystalline species and their crystalline structures could reasonably affect both the carbonation reaction kinetics and mechanism, very few contributions have been focused thus far to study their impact on the carbonation reaction, insomuch as the influence of CaO/CaCO3 crystalline domain sizes on the carbonation reaction with CaO-based solid sorbents has never been investigated. The research project summarized in this work of thesis has been focused on the investigation of the CaO carbonation reaction with the goal of clarifying these unresolved aspects. Sorbent samples were first characterized by thermo-gravimetric analysis (TGA). CaO particles, directly produced in the TGA apparatus through stages of thermal decomposition in N2 atmosphere (temperature range from 650°C and 900°C), were tested to investigate their reactivity in the CO2 capture process, aiming at identifying the absorption specific rates, and confirming as common TGA analysis are reasonably affected by physical limitations, mainly mass transfer resistances. The TGA unit was fed with gas consisting of pure carbon dioxide or of a N2/CO2 mixture so that different CO2 partial pressures were used within a range of 0.05 and 1 bar while carbonation temperatures were varied from 450°C up to 650°C. Some CaO sorbent samples were also preliminary prepared through a stage of calcination realized in a separate muffle furnace. Different operating conditions in terms of calcination temperatures (especially 900°C) and residence times at high temperature (from few minutes up to some hours) were used in order to produce CaO sorbent samples with different structural properties, mainly in terms of porosity and specific surface area. In fact, these factors, which are closely related to the sorbent modifications due to high temperature treatments, reasonably affect the carbonation reaction. Specific surface area measurements by N2 adsorption were performed to complete the characterization of the samples by means of BET analysis. The samples were afterwards tested during CO2 absorption processes carried out in the TGA unit under a gas flow of pure carbon dioxide (total pressure of 1 bar). Based on CaO conversions and the corresponding reaction rates measured, a simple reaction mechanism was applied to determine the kinetic parameters. An activation energy of about 45 kJ/mol was estimated, but it was reasonably associated to apparent kinetic rates. Moreover, the relationship between variation of the specific surface and porosity due to sintering and their effect on the carbonation reaction were not clearly quantify because of the uncertainty of the experimental data obtained, caused by the mass-transfer limitations that affected the TGA experiments. The X-ray powder diffraction technique was therefore applied since it can provide an alternative method to the thermo-gravimetric analysis for studying the CaO-CO2 reaction. X-ray diffraction experiments were carried out (in collaboration with the Department of Geosciences at the University of Padova) to determine the structural changes of the sorbent samples (namely phase evolution and crystallite size modifications) as a function of temperature and CO2 partial pressure. Several tests were performed using a high temperature reaction chamber, with a controlled gas inlet composition, both during the thermal decomposition (calcination/regeneration) and during the absorption processes. Calcination experiments, carried out in a N2 atmosphere (total pressure = 1 bar) and a temperature range varying between 650 and 950°C, allowed to observe that, after the complete decomposition of calcium carbonate precursor, the average crystallite size of CaO domains formed (approximately of 40 nm) considerably changes, when kept for long residence times at high temperatures. We also verified that even a low concentration of CO2 in the calcination atmosphere promotes CaO crystal size growth during the CaCO3 thermal decomposition and significantly increases the size of the nascent CaO crystalline domains. After the preparation stage of thermal decomposition, carbonation experiments using fresh calcines directly produced within the reaction chamber were performed. It was observed that differences in the crystallite size of the CaO samples apparently influence the solid sorbent reactivity in the following CO2 capture process. At the same carbonation isotherm (temperatures applied were in the range of 400-650°C), with a CO2 partial pressure of 1 bar, samples with a larger CaO crystal size (at the beginning of carbonation) showed a lower overall carbon dioxide absorption capacity, suggesting that the carbonation reaction (kinetics) could be affected by initial CaO sorbent particle crystallite size. Unfortunately, the low time resolution provided by the available standard laboratory instrumentation was not sufficient to obtain detailed information about the transformations occurring in the sample particles, especially during the initial very fast stage of the carbonation reaction, whereas the surface chemical reaction should reasonably occur with negligible effects of the product layer diffusion. Therefore, in-situ synchrotron radiation X-ray powder diffraction (SR-XRPD), performed at the Advanced Photon Source (APS) facilities of the Argonne National Laboratory, was finally applied to investigate the CaO carbonation reaction more in detail. A set of CO2 absorption experiments were conducted in a high temperature reaction capillary with a controlled atmosphere (CO2 partial pressure of 1 bar), in the temperature range between 450°C and 750°C using CaO based sorbents obtained by calcination of commercial calcium carbonate. The evolution of the crystalline phases during CO2 uptake by the CaO solid sorbents was monitored for a carbonation time of 20 min as a function of the carbonation temperature and of the calcination conditions. The Rietveld refinement method was applied to estimate the calcium oxide conversion during the reaction progress and the average size of the initial (at the beginning of carbonation) calcium oxide crystallites. The measured average initial carbonation rate (in terms of conversion time derivative) of 0.280 s-1 (± 13.2% standard deviation) is significantly higher than the values obtained by thermo-gravimetric analysis and reported thus far in the scientific literature. Additionally, a dependence of the conversion versus time curves on the initial calcium oxide crystallite size was observed and a linear relationship between the initial CaO crystallite size and the calcium oxide final conversion was identified. The evolution of the CaCO3 crystalline phase during the CaO carbonation was also investigated by means of the same technique. Maximum sizes of the calcium carbonate crystalline domains were observed in the CaCO3 crystallite size versus time curves, (specifically during the first rapid stage of the carbonation) and were identified as the average values of the critical CaCO3 product layer thickness. A relationship between this parameter and the corresponding calcium oxide conversion (at which the transition to the second slow reaction stage occurs), as well as a dependence of the carbonate product layer thickness with the initial CaO particle porosity, were found. Finally, CaCO3 critical product layer thicknesses were used to estimate the initial specific surface areas of the CaO sorbent particles afterwards utilized to calculate the kinetic parameters of the intrinsic surface carbonation reaction. A reaction rate constant of 1.89 × 10-3 mol/m2 s, with zero-activation energy, has been obtained.
Negli ultimi anni, l’interesse riguardo al problema del riscaldamento globale è cresciuto notevolmente. La comunità scientifica è concorde sul fatto che i cambiamenti climatici osservati nel mondo sono correlati alle emissioni di gas serra, in modo particolare quelle di biossido di carbonio, che sono incrementate rapidamente in seguito allo sviluppo tecnologico ed industriale ([1], [2], [3]). Il settore principalmente coinvolto nelle emissioni di CO2 è l’industria per la generazione di energia, dove gli impianti di combustione e gassificazione che sfruttano combustibili fossili sono predominanti e contano ancora oggi per più di un terzo di tutte le emissioni antropogeniche di CO2. Se si considera la continua e progressiva crescita nell’utilizzo di questi combustibili in tale settore, lo sviluppo e l’implementazione di processi caratterizzati da ridotte (se non assenti) emissioni di CO2 sono questioni che devono essere urgentemente affrontate. La cattura e lo stoccaggio dell’anidride carbonica, comunemente denominato CCS (dall’inglese Carbon dioxide Capture and Storage), rappresenta l’insieme delle tecnologie orientate appunto a separare l’anidride carbonica dalle correnti gassose industriali (oltre che al trasporto e allo stoccaggio della stessa in formazioni geologiche o nel fondo degli oceani in modo tale da isolarla dall’atmosfera a lungo termine) in modo efficiente ed economicamente conveniente, e rappresenta una possibile soluzione a breve termine per mitigare le emissioni di CO2 nell’atmosfera ([1], [4]). Tuttavia, i costi associati alle tecniche di cattura della CO2 ad oggi disponibili (come ad esempio i processi basati su lavaggi con solventi amminici) sono proibitivamente alti (soprattutto in termini di penalizzazioni nell’efficienza energetica degli impianti di produzione di energia), e rendono quindi lo sviluppo di nuovi sorbenti per la cattura del biossido di carbonio una sfida molto importante nel panorama della ricerca scientifica. Tra le diverse strategie attualmente investigate, l’ossido di calcio (CaO), facilmente ottenuto attraverso trattamenti termici di calcinazione del carbonato di calcio ampiamente disponibile e diffuso in natura, si presta come un sorbente solido particolarmente interessante/promettente che potrebbe ridurre in modo significativo i costi associati ai processi di cattura dell’anidride carbonica. La tecnica della cattura della CO2 attraverso sorbenti solidi a base di ossido di calcio è ampiamente discussa in letteratura e recentemente è stata riassunta da alcuni autori ([5], [6], [7], [8]). Essa fa riferimento alla reazione reversibile CaO (s) + CO2 (g) ↔ CaCO3 (s) e dovrebbe essere applicata attraverso cicli di calcinazione e carbonatazione, offrendo diversi vantaggi. Tuttavia, alcune problematiche, tra cui il progressivo declino nella capacità di cattura che tali sorbenti evidenziano all’aumentare del numero di cicli di assorbimento/desorbimento, ne mettono ancora in discussione l’utilizzo diffuso in applicazioni di scala industriale. La ricerca di miglioramenti e lo sviluppo di nuovi sorbenti solidi sono quindi una materia di studio attuale e, nonostante l’apparente semplicità della reazione chimica coinvolta, diversi aspetti riguardanti la carbonatazione del CaO non sono stati definitivamente chiariti. La determinazione dei parametri cinetici intrinseci della reazione di carbonatazione è una delle questioni aperte. La qualità della stima della costante cinetica della reazione superficiale (necessaria per progettare i reattori per la carbonatazione) dipende dall’accuratezza dei dati sperimentali (nello specifico delle curve di conversione vs. tempo) i quali, in tutti i contributi disponibili in letteratura, sono ottenuti (al meglio delle conoscenze dell’autore) tramite un approccio termo-gravimetrico ([15], [11], [12], [9], [10], o [21]). Tuttavia, è noto che misure TGA possono essere affette da limitazioni legate a resistenze al mass transfer, specialmente per quanto riguarda la diffusione esterna, per cui è ragionevolmente discutibile se i risultati finora riportati in letteratura siano realmente espressione della cinetica intrinseca oppure, diversamente, riproducano soltanto una cinetica di assorbimento della CO2 apparente. Un altro aspetto rilevante è la dipendenza della reazione di carbonatazione dalle proprietà strutturali del sorbente. Finora, diverse ricerche hanno focalizzato l’attenzione sull’impatto della porosità e della superficie specifica, o ancora sull’impatto della distribuzione della dimensione dei pori rispetto la reazione di carbonatazione e alla sua cinetica ([15], [17], [10], [13], [18], o [19]). Anche se la superficie specifica e la distribuzione della dimensione dei pori sono parametri probabilmente rilevanti nella determinazione della cinetica di una tipica reazione gas-solido come la carbonatazione del CaO, l’impatto delle dimensioni dei domini cristallini che formano le fasi di ossido di calcio e di carbonato sulle prestazioni dei sorbenti sono informazioni non ancora disponibili in letteratura quando ci si riferisce alla reazione di carbonatazione. Il progetto di ricerca riassunto in questo lavoro di tesi è stato quindi focalizzato sullo studio della reazione di carbonatazione del CaO e sulla caratterizzazione dei sorbenti a base di ossido di calcio, con l’obiettivo di chiarire questi aspetti emersi dalla letteratura, ancora poco risolti. Dopo avere affrontato il problema del surriscaldamento globale e aver riassunto le inequivocabili evidenze scientifiche riguardanti i cambiamenti climatici già discusse in dettaglio nei report dell’Intergovernmental Panel of Climate Change (IPCC) ([1], [2], [3] ), nel Capitolo 1 sono delineate le cause di tali cambiamenti ed la CCS viene presentata come una delle possibili strategie di mitigazione delle emissioni di CO2, focalizzando l’attenzione sullo stato dell’arte in merito alle tecnologie CCS attualmente investigate. Successivamente, viene presentata la tecnologia della cattura dell’anidride carbonica realizzata attraverso l’utilizzo di sorbenti solidi a base di ossido di calcio. Nel Capitolo 2 vengono quindi discussi gli aspetti fondamentali riguardanti la reazione di carbonatazione del CaO, descrivendo la sua termodinamica e il tipico comportamento caratterizzato da due differenti fasi di reazione ovvero, una parte iniziale veloce, controllata nei primi istanti dalla reazione chimica alla superficie, seguita da una seconda fase più lenta, controllata dalla diffusione della CO2 attraverso lo strato di carbonato di calcio prodotto. Altresì, nel capitolo sono riportate considerazioni sugli aspetti irrisolti riguardanti la reazione di carbonatazione riscontrati in letteratura, come la caratterizzazione/misura del critical product layer thickness, il quale determina la transizione tra i due regimi di reazione menzionati, ed il problema della stima dei parametri cinetici intrinseci della carbonatazione. Infine, sono proposti i principali risultati dell’investigazione preliminare condotta attraverso l’applicazione dell’approccio termo-gravimetrico. Campioni di sorbente (i.e. particelle di ossido di calcio) direttamente prodotti in TGA tramite decomposizioni termiche di CaCO3 commerciale, in atmosfera di N2 (range di temperatura tra i 650°C e i 900°C), sono state testate per analizzare la loro reattività nella fase di cattura del biossido di carbonio, con l’obiettivo di identificare le velocità di assorbimento specifiche e confermare come i tradizionali esperimenti in TGA siano affetti da limitazioni fisiche, specialmente resistenze legate a fenomeni di mass transfer. Questi esperimenti sono stati condotti alimentando un classico strumento TGA sia con CO2 pura, sia con miscele N2/CO2 in modo da variare la pressione parziale di anidride carbonica in un intervallo compreso tra 0.05 bar e 1 bar, e imponendo isoterme a diverse temperature di carbonatazione, fissate tra i 450°C e i 650°C. Alcuni campioni di sorbente sono stati anche preparati attraverso fasi di calcinazione realizzate separatamente in un forno a muffola. Diverse condizioni operative sono state utilizzate in termini di temperature di calcinazione (principalmente 900°C) e tempi di residenza a tali temperature (da pochi secondi a qualche ora), in modo da produrre particelle di ossido di calcio caratterizzate da differenti proprietà strutturali, specialmente in termini di porosità e superficie specifica. Infatti, tali fattori, che sono strettamente legati alle modificazioni strutturali alle quali questi sorbenti sono soggetti per effetto dei trattamenti termici ad alta temperatura, ragionevolmente influenzano la reazione di carbonatazione. Per completare la caratterizzazione dei sorbenti così prodotti si sono eseguite dapprima misure di superficie specifica attraverso adsorbimento di N2 e analisi BET, e in seguito se n’è testata la capacità di assorbimento di CO2 in TGA con flussi di anidride carbonica (pressione totale di 1 bar). Sulla base dei profili di conversione e delle corrispondenti velocità di reazione, un semplice modello cinetico ([9]) è stato utilizzato per determinare i parametri della cinetica intrinseca. Anche se ragionevolmente associabile ad una cinetica di reazione apparente, un’energia di attivazione di circa 45 kJ/mol è stata stimata. A seguito dell’incertezza sui dati sperimentali ottenuti e connessi a limitazioni legate a fenomeni di mass transfer, la tecnica di diffrazione ai raggi X su polveri è stata quindi applicata come metodo alternativo all’analisi termo-gravimetrica nello studio della reazione tra CaO e CO2. In particolare, nel Capitolo 3 è riportata una piccola descrizione dei principali fondamenti teorici alla base di questa tecnica; successivamente sono discussi i principali risultati raccolti durante una fase di studio realizzata in collaborazione con il dipartimento di Geoscienze dell’Università di Padova. Esperimenti di diffrazione in–situ sono stati condotti per determinare le variazioni strutturali che interessano i sorbenti solidi (in modo particolare, l’evoluzione nel tempo delle fasi cristalline (i.e. composizione) e le variazioni nelle dimensioni dei domini cristallini che caratterizzano le fasi stesse) in funzione della temperatura e della pressione parziale di anidride carbonica. Diversi esperimenti sono stati eseguiti usando una camera di reazione, applicata ad un diffrattometro da laboratorio, che ha permesso di controllare la composizione gassosa del sistema sia durante la fase di decomposizione/rigenerazione, sia durante il processo di assorbimento, nonché la temperatura del materiale testato. Esperimenti di calcinazione sono stati condotti anche qui in atmosfera di N2 (pressione totale di 1 bar) e in un intervallo di temperature tra i 650°C e i 950°C, ed hanno permesso di osservare che dopo la decomposizione completa del carbonato di calcio usato come precursore le dimensioni medie dei domini cristallini di CaO di neo formazione (approssimativamente nell’ordine dei 40 nm) cambiano considerevolmente quando il materiale è mantenuto ad alte temperature per lunghi tempi di permanenza. Inoltre, si è verificato che anche piccole concentrazioni di CO2 nell’atmosfera nella quale è condotta la fase di decomposizione favoriscono l’accrescimento dei cristalliti di ossido di calcio, tanto che le dimensioni dei nascenti domini cristallini di CaO risultano notevolmente aumentate rispetto al caso di calcinazioni condotte in atmosfera inerte. Prove di carbonatazione hanno invece evidenziato che differenze nella dimensione iniziale (ovvero, all’inizio della carbonatazione) dei domini cristallini di ossido di calcio apparentemente sembrano influenzare la reattività del campione di sorbente solido durante il processo di assorbimento della CO2: a parità d’isoterma di carbonatazione (temperature tra i 450°C e i 650°C), con pressioni parziali di CO2 di 1 bar, campioni costituiti da cristalliti più grandi hanno infatti mostrato una capacità di assorbimento della CO2 più bassa raggiungendo, al termine di esperimenti di carbonatazione nell’ordine dei 120 min, conversioni inferiori. Altresì, questa evidenza rimane confermata anche all’aumentare del numero di cicli di calcinazione/carbonatazione. Purtroppo, la bassa risoluzione temporale caratterizzante la strumentazione di laboratorio disponibile non è stata sufficiente per ottenere informazioni dettagliate sulle trasformazioni che avvengono nella struttura cristallina delle particelle di sorbente, soprattutto durante la fase iniziale (molto veloce) della carbonatazione laddove la reazione alla superficie (i.e. cinetica intrinseca) ragionevolmente ha luogo con trascurabili effetti di diffusione attraverso il product layer di carbonato. Per approfondire la caratterizzazione della carbonatazione del CaO attraverso la diffrazione dei raggi X si è pertanto scelto di incrementare le potenzialità della tecnica con l’utilizzo della radiazione da sincrotrone. Nel Capitolo 4 sono presentati i risultati sulla caratterizzazione della reazione tra CaO e CO2 ottenuti da esperimenti di diffrazione ai raggi X in-situ condotti in collaborazione con le strutture dell’Advanced Photon Source (APS) presso l’Argonne National Laboratory (Argonnne, IL, U.S.A). Un set di esperimenti di cattura della CO2 è stato completato utilizzando un sistema con capillare riscaldato appositamente sviluppato ([20]) per condurre prove di diffrazione da polveri controllando l’atmosfera di reazione (pressioni parziali di CO2 di 1 bar) e la temperatura (tra i 450°C e i 750°C), per seguire l’evoluzione delle fasi cristalline di CaO e CaCO3 durante il processo di carbonatazione di particelle di ossido di calcio prodotte per decomposizione termica di carbonato di calcio commerciale. Il metodo di raffinamento Rietveld è stato poi applicato sia per quantificare la conversione dell’ossido di calcio durante il procedere della reazione, sia per stimare la dimensione media dei domini cristallini di CaO all’inizio della carbonatazione. Dai profili di conversione è stata valutata una velocità media iniziale della carbonatazione (espressa in termini di derivata della conversione rispetto al tempo) pari a 0.280 s-1 (deviazione standard di ± 13.2%) che è risultata significativamente più alta rispetto ai valori ottenuti da analisi termo-gravimetriche e riportati finora in letteratura ([9], [15] o [12]). E’ stata inoltre osservata una dipendenza dei profili di conversione rispetto al tempo dalla dimensione iniziale dei cristalliti di ossido di calcio, come pure è stata identificata una relazione lineare tra questa grandezza e la conversione finale. Analogamente, anche l’evoluzione del carbonato di calcio durante la fase di assorbimento della CO2 è stata monitorata: dimensioni massime dei domini cristallini di CaCO3 sono state osservate nei profili del crystallite size del carbonato in funzione del tempo (in particolare durante la prima rapida fase della reazione), e sono state identificate come i valori medi del critical product layer thickness. Una relazione tra questo parametro e le corrispondenti conversioni dell’ossido di calcio, alle quali si può ragionevolmente associare la transizione alla seconda fase caratteristica della carbonatazione (i.e. regime controllato dalla diffusione della CO2 attraverso lo strato di prodotto), è stata individuata, come anche tra il critical product layer thickness e la porosità iniziale delle particelle di sorbente. Infine, i valori individuati sono stati usati per stimare la superficie specifica iniziale delle particelle di CaO utilizzate negli esperimenti di carbonatazione; tali superfici sono quindi state usate nella stima dei parametri cinetici intrinseci della reazione di carbonatazione, ottenendo una costante di reazione pari a circa 1.89 × 10-3 mol/m2 s, con energia di attivazione nulla.

The adsorption and separation of platinum(IV) and palladium(II) chlorido species (PtCl₆²⁻ and PdCl₄²⁻) on polystyrene-based beads and nanofibers as well as silica microparticles functionalized with polyamine centres derived from ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) is described. The functionalized sorbent materials were characterized by using microanalysis, SEM, XPS, BET and FTIR. The nanofiber sorbent material functionalized with ethylenediamine (F-EDA) had the highest loading capacity which was attributed to its high nitrogen content (10.83%) and larger surface area (241.3m²/g). The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies in 1 M HCI. The adsorption studies for both PtCl₆²⁻ and PdCl₄²⁻ on the polystyrene-based sorbent materials fit the Langmuir isotherm while the silica-based sorbents fitted the Freundlich isotherm with R² values > 0.99. In the column experiment the highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively on the nanofiber sorbent material based on ethylenediamine (EDA). The polystyrene and silica-based resins with triethylenetetramine (TETA) functionality (M-TETA and S-TETA) showed selectivity for platinum and palladium, respectively. Metal chlorido complexes loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as teh eluting agent with quantitative desorption efficiency under the selected experimental conditions. The separation of platinum from palladium was partially achieved by selective stripping of PtCl₆²⁻ with 0.5 M of NaClO₄ in 1.0 M HCI with PdCl₄²⁻ was eluted with 0.5 M thiourea in 1.0 M HCI. The selectivity of the M-TETA and S-TETA sorbent materials was proved by column separation of platinum(IV) and palladium(II), respectively, from synthetic solutions containing iridium(IV) and rhodium(III). The loading capacity for platinum on M-TETA was 0.09 mg/g while it was 0.27 mg/g for palladium on S-TETA.
Acrobat PDFMaker 10.1 for Word
Adobe Acrobat 9.54 Paper Capture Plug-in

Metal organic frameworks (MOFs) is a quite recently discovered porous material group which shows potential in many different areas. One of these areas is carbon capture; the framework structure of the porous materials allows gas molecules to adsorb to the surface of the pores. MOFs are conventionally synthesised at high temperatures and with hazardous solvents. The goal of this projectwas to synthesise highly porous MOFs at room temperature with water as the main solvent, using environmentally friendly and non-hazardous precursors. As well as the room temperature synthesis, conventional synthesis methods were used with the same precursors as comparison. The materials were characterised with X-ray diffraction, thermogravimetrical methods and IR-spectroscopy. To assess the porosity of the materials, gas adsorption evaluation was performed with CO2, N2, SF6, and CH4 at 20⁰C. In the end, three novel porous magnesium-based materials and one zirconium-based material were successfully synthesised. One of the magnesium-based materials showed a moderately high CO2 adsorption (2.38mmol/g), and could be synthesised at room temperature. The zirconium-based material showed a remarkably high selectivity (17.7) for SF6 over N2 and a high surface area (550m2/g)

SESMR (Sorption Enhanced Steam Methane Reforming), SMR (Steam Methane Reforming) avec capture de CO2 in situ par un adsorbant solide, peut amener à une exploitation durable du gaz naturel pour la production de H2. La thèse, partie du projet de recherche ASCENT (Advanced Solid Cycles with Efficient Novel Technologies), concerne le développement de matériaux combinés adsorbants catalyseurs Ni-CaO-mayenite pour le SESMR, aux fins d’étudier les influences dues à la fraction de Ni, aux sels précurseurs du Ni (Ni acétate ou Ni nitrate), et à la fraction de CaO disponible. Les techniques ICP AES, XRD, BET/BJH, SEM/EDS, TEM/EDS, TPR et TGA ont été utilisés pour caractériser les matériaux synthétisés. La réactivité a été évaluée par des tests en lit fixe à l’échelle du microréacteur, qui ont aussi permis une sélection des matériaux les plus prometteurs pour une étude de l’applicabilité industrielle par tests multi cycliques SESMR/régénération de solides par un réacteur automatisé à lit fixe
Sorption enhanced steam methane reforming (SESMR), steam methane reforming (SMR) with in situ CO2 sorption by a solid sorbent, can lead to a sustainable exploitation of natural gas to produce H2. (CSCM). This thesis, as a part of ASCENT (Advanced Solid Cycles with Efficient Novel Technologies) project, deals with Ni-CaO-mayenite combined sorbent-catalyst material for SESMR, to study the effect of Ni fraction, its precursor salt (Ni nitrate or Ni acetate), and free CaO fraction. ICP AES, XRD, BET and BJH methods, SEM EDS, TEM EDS, TPR and TGA were used to characterize synthesized materials. Their reactivity was evaluated by tests in a packed bed microreactor, which served also as a screening tool to choose the most promising materials. Their industrial applicability was assessed by multicycle SESMR/regeneration tests in an automated packed bed bench scale rig

Solid phase extraction (SPE) has been developed as an alternative to liquid-liquid extraction (LLE) in the sample preparation process. The advantages of SPE over LLE are that it is a more useful, reliable tool for sample preparation, which offers greater selectivity. The selectivity of an SPE sorbent is vital for the isolation of analyte from a biological matrix containing a myriad of interferences. The use of conventional ion exchange SPE for such an extraction process might not be adequate due to the adverse effects of interfering ions. Metals immobilized on various modified silicas were investigated to determine if the addition of metals improved selectivity. The selectivity of these sorbents was studied by the extraction of analytes from high ionic strength matrices. Extraction selectivity was found to depend on different factors, including the type of bonded species, metal ions used and the analytes, counter ions, sample pH and elution solvent composition. Utilizing coordination complexation between analytes and immobilized metal ions, particularly when different phases are stacked, can increase selectivity for a particular analyte. Metals immobilized by ionic exchange sorbents were observed to retain analytes of tridentate chelation capability more than immobilized metals on bonded chelators. However, bonded chelators were observed to be advantageous because they more strongly retained metal ions, relative to ionic exchangers. The interactions of immobilized silver ions with unsaturated molecules utilizing SPE were investigated. Retention of silver ions was found dependent on the nature of bonded phase. The silver ions immobilized by coordination interactions showed weaker retention than silver immobilized by ionic interactions. Retention of alkenes by silver was found to have higher flow dependence, as compared to ionic exchange or ligand exchange processes. Retention of analytes was observed to depend on a variety of factors, including the type of bonded phase used for silver immobilization, the composition of the elution solvent, steric factors, the degree of unsaturation, the geometry and position of the double bonds of the analyte molecules. Extraction selectivity for geometrical isomers decreased when silver ions were immobilized by long chain cation exchangers versus those on conventional short chain cation exchangers.

Poly(1-methylpyrrol-2-ylsquaraine) (PMPS) particles are a fine blue-black insoluble powder. Scanning electron microscopy (SEM) pictures reveal that the PMPS particles are microspheres with diameters ranging from 1.3 - 4 micrometers (distribution peaking at 1.9 micrometers). The absorption capacity values of PMPS particles were studied for a large majority of the elements in the periodic table in order to establish a pattern or trend in absorption. The elements specifically targeted at the beginning of the research were the biological elements vital to sustain life and the heavy metals that pose a threat to the environment via pollution and poisoning. Fifty-four elements were investigated in total and all absorbed in varying amounts ranging from 0.01 mmol/g for caesium up to 5.66 mmol/g for phosphorous. It was found that varying the initial elemental compound, temperature and solvent concentrations vastly altered the amount of element absorbed. The majority of elements absorbed best when dissolved in hot concentrated hydrochloric acid at 50oC, some preferred cold conditions (4oC) and/or a neutral solvent (water). The freshness of the elemental compound had a huge impact on the absorption capacities, i.e. new compounds absorbed much better than old stock. A comparison between chloride salts and the hydroxides of Group 1 alkali metals revealed that the hydroxides absorbed much better than the salts, sometimes with more than a ten-fold increase. Release profiles were studied for PMPS particles containing eleven different elements when subjected to an aqueous medium. The study focused on some of the elements that are commonly utilised in industry and also the soft acids and bases primarily because they had some of the highest sorption values and the fact that the majority are known to be particularly toxic to man. The amount of ions released varied enormously ranging from 0% release for selenium up to 83% for arsenic. It was interesting to observe that arsenic had the highest percentage release despite having the lowest sorption uptake and selenium had the lowest (zero) percentage release despite having one of the highest sorption uptakes. Analysis of the release data revealed that there appears to be two types of profile emerging. In the first type of profile the metallic ions leached out of the PMPS particles slowly over a period of time until equilibrium was reached whereupon no more ions were released. This happened for the arsenic, copper, lead, mercury, cadmium, silver and gold ions. In the second type of profile all of the free ions were released as soon as water was added, in the first 2 mL aliquot. This happened for the manganese, sodium and caesium ions. It would appear that the ions that have the gradual release profile are the heavier ions on the right hand side of the periodic table, which also means that they are soft acids or bases. The ions that have the second type of profile, where release was achieved in the first aliquot are situated on the left hand side of the periodic table and were all found to be hard acids. Over-coating studies using PMPS particles containing copper and sodium were separately investigated. The results revealed that PMPS-Cu particles when overcoated with a polymer do appear to have a slow release profile.

Replacing the lost Phosphates from different ecosystems is not a question it’s an onus. This none replaceable and renewable resource is one of the vital nutrients where without it, cells, crops and human beings cannot function and live. Though available in environment, its natural cycle is disturbed as its need especially in agriculture sector increases significantly. Phosphorus recovery from waste water sorbents is one of the innovative and promising concepts. The core goal of this paper is to evaluate the phosphorus desorbing capacity of two reactive materials (waste water sorbents) using chemical extracts. The experimental work emphasized on investigation four extracts, HNO3, NaHCO3, P-AL and H2O on phosphate desorption capacity of two inorganic reactive materials namely Polonite® and Sorbulite® which are widely known for their high P-sorption capacity. The kinetics and desorption were examined in batch experiments and consequently the plant availability were investigated using Flow Injection Analyzing (FIA) spectroscopy (wet chemistry) method. The maximum average orthophosphate desorption at 100 rpp for 48 hrs was interpreted to be 33.12 mg g−1and 3.11 mg g−1 from Sorbulite® and Polonite® respectively using 4M HNO3 extract. The orthophosphate desorption characteristic using the above extracts tended to decrease in the following order HNO3 ≤ P-AL ≤ NaHCO3 ≤ H2O. Polonite® shows a higher recovery potential, where almost 6 times higher ammonium lactate (AL)-extractable P was observed when compared with Sorbulite®. Batch experiment was proved to be a tool for investigating and evaluating Phosphorus desorption capacity of mineral-based filter materials.

Pipeline natural gas is the primary fuel of choice for distributed fuel cell-based applications. The concentration of sulfur in odorized natural gas is about 30 ppm, with acceptable levels being <1 ppm for catalyst stability in such applications. Packed bed technology for desulfurization suffers from several disadvantages including high pressure drop and slow regeneration rates that require large unit sizes. We describe a novel Rapid Temperature Swing Adsorption (RTSA) system utilizing hollow fibers with polymer 'binder', impregnated with high loadings of sulfur selective sorbent 'fillers'. Steam and cooling water can be utilized to thermally swing the sorbent during the regeneration cycles. An impermeable, thin polymer barrier layer on the outside of fiber sorbents allows only thermal interactions with the regeneration media, thereby promoting consistent sorption capacity over repeated cycles. A simplified flow pattern minimizes pressure drop, porous core morphology maximizes sorption efficiencies, while small fiber dimensions allows for rapid thermal cycles.

A new concept of a "fiber sorbent" has been investigated. The fiber sorbent is produced as a pseudo-monolithic material comprising polymer (cellulose acetate, CA) and zeolite (NaY) by applying hollow fiber spinning technology. Phase separation of the polymer solution provides an appropriately porous structure throughout the fiber matrix. In addition, the zeolite crystals are homogeneously dispersed in the polymer matrix with high loading. The zeolite is the main contributor to sorption capacity of the fiber sorbent. Mass transfer processes in the fiber sorbent module are analyzed for hydrogen recovery and compared with results for an equivalent size packed bed with identical diameter and length. The model indicates advantageous cases for application of fiber sorbent module over packed bed technology that allows system downsizing and energy saving by changing the outer and bore diameters to maintain or even reduce the pressure drop. The CA-NaY fiber sorbent was spun successfully with highly porous structure and high CO2 sorption capacity. The fiber sorbent enables the shell-side void space for thermal moderation to heat of adsorption, while this cannot be applied to the packed bed. The poly(vinyl alcohol) coated CA-NaY demonstrated the thermal moderation with paraffin wax, which was carefully selected and melt at slightly above operating temperature, in the shell-side in a rapidly cycled pressure swing adsorption. So this new approach is attractive for some hydrogen recovery applications as an alternative to traditional zeolite pellets.

Hydrophobic dipeptide crystals recently emerged as novel “organic zeolites” featuring tailorable pore size. In fact, seven out of nine pairwise combinations of L-isoleucine, L-valine and L-alanine amino acids crystallize according to the same charge-assisted hydrogen bond pattern, generating a family of microporous materials with right-handed 1D channels, having diameters in the sub-nanometer domain (<6Å), aliphatic environment and different degrees of helicity. The relationship between pore size and material properties was investigated with respect to gas separation, exploiting the affinity of carbon dioxide for the hydrophobic nanochannels of L-alanyl-L-valine (AV), L-isoleucyl-L-valine (IV) and L-valyl-L-isoleucine (VI). Reversible CO2 capture from an equimolar mixture of CO2 and methane, at room temperature and 1 atmosphere, was demonstrated with increasing purification performance with decrease in pore size. Dipeptide were also used as nanovessels in radical polymerizations with the aim of controlling otherwise non-specific reactions. Diene monomers (trans-1,3-pentadiene and isoprene) only yield linear 1,4-trans polymer in accordance with 1-dimensional pore geometry, while poly(acrylonitrile) (PAN) could be obtained as a stereoregular isotactic product by acrylonitrile polymerization in AV dipeptide. Finally, taking advantage of the dipeptide lability and unique thermal properties of poly(acrylonitrile), AV-PAN nanocomposites were used as a scaffold to obtain carbon replicas of the starting nanocomposite crystals (carbon micro-fibrils) showing anisotropic arrangement of the graphite domains.

Les digestats des boues d'épuration (SSD) et les digestats de la fraction organique des déchets ménagers (OFMSWD) ont été récemment considérés comme des sources potentielles pour la production de biochars en raison des quantités grandissantes de digestats solides restant à la fin de la digestion anaérobie. La pyrolyse des digestats solides est connue comme une technique pour promouvoir le recyclage des déchets organiques et générer des bio-produits à valeur ajoutée (i.e. biochar). En outre, en raison d'une capacité de sorption des métal(loïde)s des biochars moins bonnes par rapport aux charbon actifs traditionnels, la modification chimique des biochars bruts est considérée comme une alternative pour améliorer les propriétés de surface des biochars et induire ainsi une meilleure capacité de sorption des métal(loïde)s. Les biochars ont été traités avec 2 M de KOH ou 10% de H2O2, suivis d'un lavage en batch seul ou batch combiné avec un lavage en colonne à l’aide d'eau ultrapure. Les analyses des propriétés de biochar, le pH du point de charge nulle, la surface spécifique et la capacité d'échange cationique ont été effectuées sur les biochars bruts et modifiés afin de relier leurs propriétés de surface au comportement de sorption vis-à-vis des métal(loïde)s. Tous les biochars ont ensuite été utilisés pour étudier l'influence du traitement chimique et de la procédure de lavage des biochars sur le comportement de sorption du Pb(II), Cd(II) et As(III, V) à travers l’étude de la cinétique et des isothermes de sorption. De plus, l’évolution de l'état redox As (i.e. As(III, V)) pendant la sorption de l'As(III) sur la surface du biochar et en solution liquide a été déterminée par extraction solide-liquide suivie d'une analyse en chromatographie liquide.Les résultats ont montré des augmentations de la capacité de sorption pour le Pb(II), le Cd(II) et l’As(V) après traitement chimique du biochar. Par exemple, la capacité de sorption maximale (Qm) (Cd(II)) a été augmentée de 15,4 µmol g−1 sur le biochar de SSD brut à 306,1 µmol g−1 après le traitement au KOH (au pH initial de 5,0). De même, la valeur de Qm du Pb(II) a augmenté de 6,5 mg g−1 (biochar de SSD) à 25 mg g−1 sur le biochar modifié par H2O2. Néanmoins, la capacité de sorption du biochar SSD modifié par KOH n'a pas été déterminée en raison de l’impossibilité de modéliser les données expérimentales avec le modèle de l’isotherme de Langmuir. Cela indique qu'un lavage insuffisant du biochar SSD modifié par KOH peut inhiber la sorption de Pb(II) en raison de la libération de composés organiques dissous de ce biochar pouvant interagir avec Pb2+ et ainsi former des complexes Pb-ligand dans la solution. Ceci met en évidence le rôle important de la procédure de lavage sur l’efficacité de la sorption du Pb(II) sur le biochar. L’étude de la distribution de l’état redox de l'arsenic a montré une oxydation importante (70%) de As (III) en As (V) dans le biochar SSD traité au KOH avec lavage par batch, tandis que l'As(III) a été partiellement oxydé (7%) dans le biochar SSD traité au KOH avec un lavage en colonne. L'extraction de l’arsenic fixé par les biochars suivie d'une analyse par chromatographie en phase liquide a été établie avec succès pour récupérer quantitativement de l'As(III, V) Il a été montré que l'oxydation de As(III) était fortement induite par le biochar et, dans une moindre mesure, par des composés dissous libérés par les biochars.En résumé, les biochars de digestat modifiés par traitement chimique suivi d'une procédure de lavage appropriée du biochar peuvent être utilisés avec succès comme sorbants de Pb(II), Cd(II) et As(III, V). En outre, l'évolution de la distribution redox de l’arsenic dans les biochars et les solutions liquides à l'aide de l'extraction de liquide solide et de l'analyse chromatographique a été déterminée. Cela permet de mieux comprendre la transformation entre As(III) et As(V) lors la sorption de l’arsenic sur les biochars
Sewage sludge digestate (SSD) and the organic fraction of municipal solid waste digestate (OFMSWD) are currently considered as alternative feedstocks for biochar production due to the high amount of the organic solid waste remaining at the end of the treatment. The pyrolysis of solid digestate is known as an alternative to promote the recycling of organic wastes and generate added-value bio-products (e.g. biochar). Generally, the digestate biochar has a much lower sorption capacity for metal(loid)s compared to activated carbons. Therefore, chemical treatment is considered as a potential option to improve the biochar surface properties and thus inducing a better sorption ability for metal(loid)s on the biochar surface. The biochars were treated with 2 M KOH or 10% H2O2 followed by batch washing or batch and subsequent column washings with ultrapure water. The physicochemical properties including the pH of point of zero charge, the surface area and cation exchange capacity were determined for all the biochars in order to link their improved surface properties to the enhanced sorption ability for metal(loid)s. All the biochars were then used to study the influence of chemical treatment and biochar washing procedure on the sorption behavior of Pb(II), Cd(II) and As(III, V) through the batch sorption kinetics and isotherms. Moreover, the As redox state distribution (i.e. As(III, V)) during the As(III) sorption onto the biochar surface and in liquid solution was determined by using solid-liquid extraction followed by liquid chromatographic analysis. Results showed increases of the sorption ability for Pb(II), Cd(II) and As(V) after chemical treatment. For instance, the maximum sorption capacity (Qm) of Cd(II) was increased from 15.4 µmol g−1 on the raw SSD biochar to 306.1 µmol g−1 after the KOH treatment (at initial pH 5.0). Similarly, the Qm of Pb(II) was also increased from 6.5 mg g⁻1 (raw SSD biochar) to 25 mg g⁻1 on the H2O2 modified SSD biochar. However, the sorption capacity for Pb(II) was not determined after KOH treatment due to the failing of the Langmuir isotherm model to fit the experimental data. This indicates that insufficient washing of the KOH-modified SSD biochar can hinder the Pb(II) sorption due to the release dissolved organic compounds from this biochar that may interact with Pb2+ and thereby forming Pb-ligand complexes in the solution. This highlights an important role of washing procedure for Pb(II) sorption by the biochar. The As redox distribution showed a large oxidation (70%) of As(III) to As(V) in KOH-modified SSD biochar with batch washing, while As(III) was partially oxidized (7%) in the KOH-modified SSD biochar with batch and subsequent column washings. The As extraction followed by liquid chromatographic analysis was successfully established to quantitatively recover arsenic (i.e. As(III, V)). The oxidation of As(III) was strongly induced by the biochar and to a lesser extent by the release of dissolved compounds from the biochar. In summary, digestate biochars with the chemical treatment followed by a proper biochar washing procedure can be successfully used as potential sorbents to enhance the Pb(II), Cd(II) and As(III, V) sorption capacity. Moreover, the determination of As redox distribution on the biochars and in liquid phase during the sorption process can be achieved through the As extraction and chromatographic analysis, providing a better understanding of the transformation between As(III) and As(V) in the biochar-liquid sorption system

O crescimento da população mundial e a expansão industrial são fatores que atualmente desencadeiam um aumento no consumo de produtos e geração de resíduos. Frequentemente utilizados na medicina tradicional e veterinária, os antibióticos são classificados como uma classe emergente de poluentes, pois, devido à sua baixa taxa de degradação e à ineficácia dos sistemas de tratamentos de água, encontram-se disseminados no meio ambiente e nos alimentos. Em consequência desse fato, estudos para o desenvolvimento de novos materiais e métodos que removam estes contaminantes utilizando menor quantidade de consumíveis químicos e a baixo custo, têm sido um campo em desenvolvimento na química analítica. Inserido nesse contexto encontra-se o grafeno, que devido à sua estrutura de anéis aromáticos com elétrons π deslocalizados e elevada área superficial (3600 m2/g), pode favorecer fenômenos de sorção, elevando a eficiência na extração de contaminantes presentes em matrizes complexas. O objetivo do projeto foi sintetizar e caracterizar novas fases sorventes à base de grafeno para atuar no preparo da amostra avaliando a eficácia destas na remoção de tetraciclinas presentes em leite. Para isso, utilizou-se da microextração por sorvente empacotado MEPS como método de preparo de amostra com posterior análise por cromatografia líquida acoplada a espectrometria de massas HPLC-MS/MS. A caracterização dos materiais foi feita através de microscopia eletrônica de varredura MEV e espectroscopia vibracional na região do infravermelho IV revelando eficácia na síntese das folhas de óxido de grafeno, assim como, no recobrimento das partículas de sílica com os novos materiais. Foram avaliadas as fases extratoras: G, GO-SIL, G-Sil e C18-G-Sil com relação a eficiência na extração das tetraciclinas. A fase G-Sil mostrou-se a mais apropriada para continuidade do estudo, pois apresentou os melhores resultados. Com o objetivo de otimizar a etapa de preparo de amostra, foi feito um planejamento fatorial fracionário 24-1 avaliando as variáveis químicas: solvente de eluição, força iônica, pH da solução de lavagem e inclusão de EDTA na solução tampão de Mcllvaine (pH 4.2). Posteriormente foi feito um planejamento fatorial completo 23 visando a otimização dos ciclos de extração da MEPS, possibilitando determinar a condição ótima de extração do método. Baseando-se no documento: ICH - Q2 (R1) guideline, a metodologia foi submetida a testes para avaliar as figuras de mérito referentes a validação analítica. O método apresentou faixa linear de 15 - 110 µg/L, LQ entre 0,05 e 0,9 µg/L e boa seletividade. A precisão foi avaliada intra e inter-dia apresentando desvio padrão relativo - RSD abaixo de 18%. Ao final do desenvolvimento do estudo foram analisadas onze amostras reais incluindo leite bovino, caprino, ovino e leite em pó. A aplicação em amostras de diferentes espécies reforça a versatilidade do método desenvolvido, além de evidenciar o elevado potencial dos novos materiais de grafeno para atuar como sorvente no preparo da amostra.
Nowadays, the rise of world population and industrial expansion are leading to an increase in consumption and consequently waste generation. Large quantities of chemical residues are released into the environment affecting humans and wildlife. Among these residues, antibiotics used in medicine and veterinary are classified as an emerging contaminant due to their low degradation rate, ineffectiveness of wastewater treatment and consequently water and food contamination. An effort has been made to develop microextraction techniques to remove these drugs using reduce volume of solvent and chemical consumable and researches of new sorbent phases are increasing due the high potential to improve these microextraction techniques. Recent studies pinpoint graphene (G) as an effectively sorbent phase to act in sample preparation. G has a structure composed by carbon nanosheets arranged in a honeycomb pattern with large surface area (3600 m2 /g) and delocalized π-electrons system that suggests good interaction between them and contaminants compounds such as veterinary drugs, pesticides, personal care products etc. This study focuses to evaluate sorbent phases based upon graphene particle supported on silica to analyze Tetracycline residues present in milk. For this purpose, was used microextraction by packed sorbent - MEPS as sample preparation method with analysis by liquid chromatography and mass spectrometry. The characterization of synthesized materials was performed by scanning electron microscopy - SEM and vibrational spectroscopy in infrared region - FTIR. The results suggest that synthesis of graphene\'s particles as well as the coating of silica surface with these materials were both performed. To evaluate extraction efficiency each sorbent material: GO-Sil, G-Sil, G, C18-GO-Sil were tested in MEPS and confronted to commercial phases: C8 and C18. By the results, G-Sil was choose to application as sorbent phase. MEPS extractions were optimized and the effect of some factors was investigated by application of experimental design. Firstly, a factorial experimental design 2(4-1) was executed to evaluate chemistry variables such as elution solvent, washing solution, media ionic strength and inclusion of EDTA salt in Mcllvaine solution. After, an experimental design 23 was made in order to estimate the cycles of MEPS extraction like sampling, washing and elution steps. By the results, an optimized extraction conditional was achieved and evaluation of validation parameters was carried out on sequence based on the ICH - Q2 (R1) guide. The method showed linearity ranging from 15 - 110 µg/L, LOQ values from 0,05 to 0,9 µg/L and good selectivity. Precision showed relative standard deviation RSD less than 18% to intra and inter-day analysis. The developed method was applied in analysis of eleven milk samples including bovine, caprine and ovine milk and milk powder. Application in samples from different species enhances the versatility of this analytical method and show the great potential for graphene\'s particles to act as sorbent phase in sample preparation.

Increasing CO2 emissions from the energy and industrial sectors are a worldwide concern due to the effects that these emissions have on the global climate. Carbon capture and storage has been identified as one of a portfolio of technologies that would mitigate the effects of global warming in the upcoming decades. Calcium looping is a second generation carbon capture technology aimed at reducing the CO2 emissions from the power and industrial sectors. This thesis assesses the improvement of the calcium looping cycle for CO2 capture through enhanced sorbent production and testing at lab-, bench- and pilot-scale, and a new operational mode with high oxygen concentrations in the calciner through experimental campaigns in Cranfield’s 25 kWth pilot unit. Novel biomass-templated sorbents were produced using the pelletisation technique and tested at different conditions in a thermogravimetric analyser (TGA) and a bench-scale plant comprising a bubbling fluidised bed (BFB) reactor. Moreover, the effects of sorbent poisoning by SO2, and the influence of steam were studied in order to explore the effects of real flue gas on this type of material. In addition to the chemical performance, the mechanical strength, i.e. resistance to fragmentation of these materials was tested. In additon, two different kinds of enhanced materials were produced and tested at pilot-scale. Namely, calcium aluminate pellets and HBr-doped limestone were used in experimental campaigns in Cranfield’s 25 kWth pilot plant comprising a CFB carbonator and a BFB calciner. The suitability of these materials for Ca looping was assessed and operation challenges were identified in order to provide a basis for synthetic sorbent testing at a larger scale. Lastly, a new operational mode was tested, which is aimed at reducing the heat provided to the calciner through high oxygen concentration combustion of a hydrocarbon (in this case natural gas) in the calciner. This approach reduces or even eliminates the recirculated CO2 stream in the calciner. In consequence, this results in a lower capital (reduced size of the calciner) and operational cost (less oxygen and less fuel use). Several pilot plant campaigns were performed using limestone as solid sorbent in order to prove this concept, which was successfully verified for concentrations of up to 100% vol oxygen in the inlet to the calciner.

Urban stormwater is today recognized as a significant source of pollution that has contributed to the deterioration of water quality in lakes and streams. Of the pollutants, metals are commonly occurring in stormwater and can cause major damage when released into the receiving waters. A promising treatment method for removing these metals before it reaches the receiving waters is to filter the water in various filter technologies such as catch basin inserts. In this study, the potential of five materials to remove dissolved copper (Cu) and zinc (Zn) from stormwater was investigated. The study was initiated with batch equilibrium tests to assess the sorption capacity of the materials at different metal concentrations relevant for stormwater. This was done in both single and binary batches to investigate whether or not any competitive sorption occurred between the metals. Langmuir, Freundlich and Sips isotherm models were adapted to the obtained data. Through geochemical modelling, it was also possible to investigate whether precipitation of metals was likely. Finally, kinetic studies were conducted to investigate whether the reaction rate of Cu and Zn was relevant in the context of catch basin inserts. The results showed that the biochar had the highest sorption capacity followed by peat, bark, milkweed, and polypropylene. It could also be noted that Cu competed with Zn binding sites at high concentrations and that the sorption capacity of biochar, peat and bark, at concentrations between 50-100 μg/l Cu and 50-500 μg/l Zn, was sufficient to meet the limits set for stormwater emissions. For these sorbents, the reaction rate was also significant. Kinetics tests showed that at an initial concentration of 1,000 μg/l, 83% of the metals were sorbed after 5 minutes and after 10 minutes this number was 93%. Bark and peat also showed low effluent pH and leaching of dissolved organic carbon (DOC). The Langmuir and pseudo-second order equation could be well adapted to the data while geochemical modelling showed that precipitation of metals was unlikely. This suggests that chemical adsorption may be the mechanism that largely accounted for the removal of Cu and Zn. The results of this study can hardly be used to estimate the field performance of stormwater filters, but can be used as a basis for comparing and selecting sorbents for subsequent column tests.
I denna studie undersöktes potentialen för fem material att avskilja löst koppar (Cu) och zink (Zn) från dagvatten. Studien inleddes med skaktest för att testa sorptionsförmågan hos materialen vid olika metallkoncentrationer relevant för dagvatten. Detta gjordes i både singel och binära test för att undersöka om någon konkurrerande sorption skedde mellan metallerna. Langmuirs, Freundlichs och Sips isotermmodeller anpassades även till resultatet. Genom geokemisk modellering var det även möjlig att undersöka om utfällning av metaller var sannolik. Till sist gjordes kinetiska studier för att undersöka om reaktionshastigheten för sorption av Cu och Zn till filtermaterialen var relevanta i ett brunnsfiltersammanhang. Resultaten visar att biokol hade den största sorptionsförmågan följt av torv, bark, sidenört och polypropylen. Det kunde även konstateras att koppar konkurrerade om sorptionsplatser för zink vid högre koncentrationer och att sorptionskapaciteten för biokol, torv och bark, vid koncentrationer mellan 50-100 µg/l Cu och 50-500 µg/l Zn, är tillräckligt hög för att uppfylla gränsvärdena för utsläpp av dagvatten. För dessa sorbenter var reaktionshastigheten betydande. Kinetiktesten visade att vid en initial koncentration på 1,000 µg/L var 83% av metallerna sorberade efter 5 minuter och efter 10 minuter var denna siffra uppe i 93%. Bark and torv uppvisade även ett lågt uppmätt pH och lakade löst organisk kol (DOC). Langmuir och pseudo-andra ordningens ekvation kunde anpassas väl till datat samtidigt som den geokemiska modelleringen visade att utfällning av metaller var osannolikt. Detta antyder att kemisk adsorption kan vara den mekanism som till störst del stod för avskiljningen av Cu och Zn. Studien kan inte fastställa något om filtermaterialens fältprestanda, men kan användas som underlag för att jämföra och att välja sorbenter för efterföljande kolumntester.
Formas project 2016-75

Дисертація розглядає розроблення науково-методологічних основ екологічно безпечних технологій очищення стічних вод сорбентами мінерально-сировинної бази України, теоретичні та експериментальні дослідження процесів адсорбційного очищення рідинних середовищ в системах з природними дисперсними сорбентами, процеси модифікування цих сорбентів та процеси розділення багатокомпонентної системи від забрудників методом селективної адсорбції (промислової хроматографії). Вирішена науково-технічна проблема дала змогу розробити та впровадити високоефективні технології очищення стоків, забруднених барвниками, органічними розчинниками та радіонуклідами, які є одними із найнебезпечніших забрудників гідросфери. Теоретично та експериментально досліджено процеси кислотного модифікування бентонітів за умов використання реактора з мішалкою та кульового млина. Встановлені оптимальні умови його перебігу, розроблені адекватні математичні моделі, встановлені значення кінетичних коефіцієнтів та запропоновані принципові технологічні схеми реалізації цих процесів. Розроблені теоретичні основи моделювання процесів очищення рідинних середовищ адсорбцією природними сорбентами. Запропонована математична модель процесу для встановлення лімітуючої стадії на основі розрахунку зовнішньодифузійних параметрів (на основі теорії локальної ізотропної турбулентності для апаратів з механічними пристроями) та внутрішньодифузійних параметрів (із використанням теоретичних розрахунків ефективних коефіцієнтів внутрішньої дифузії). Досліджено сорбцію Сs та Sг на модифікованих глинистих мінералах та встановлено оптимальні умови процесу. Доведено, що у разі застосування модифікованих глинистих сорбентів не спостерігається вторинне забруднення води металами-модифікаторами. Проведено ідентифікацію експериментальних даних адсорбції радіонуклідів існуючим теоретичним ізотермам сорбції. Досліджені аспекти використання рідинної хроматографії в промислових умовах для розділення суміші органічних розчинників. Рішення адсорбційної моделі використані для прогнозування конкурентної рівноваги адсорбції розчину та активного компонента рухомої фази на основі ізотерм адсорбції, а стандартні ізотерми адсорбції визначені на підставі додаткових даних адсорбції, виміряних в інертній системі. Запропоновано принципову технологічну схему хроматографічного розділення суміші органічних розчинників. Основні результати передані для впровадження у виробництво та навчальний процес.
Диссертация посвящена разработке научно-методологических основ экологически безопасных технологий очистки сточных вод от органических красителей, растворителей и радионуклидов сорбентами минерально-сырьевой базы Украины. В работе приведены теоретические и экспериментальные исследования процессов адсорбционной очистки жидкостных сред природными дисперсными сорбентами, методы модифицирования этих сорбентов в зависимости от необходимой степени их активации, а также рассмотрена перспективность использования жидкостной хроматографии для разделения многокомпонентной системы органических растворителей методом селективной адсорбции (промышленной хроматографии). Решенная научно-техническая проблема дала возможность разработать и внедрить высокоэффективные технологии очистки стоков, загрязненных красителями, органическими растворителями и радионуклидами. На основании теоретических и экспериментальных исследований процессов кислотного модифицирования бентонитов разработана классификация методов модифицирования природных сорбентов в зависимости от вида загрязнителя, а также рассчитаны адекватные математические модели, вычислены значения кинетических коэффициентов и предложены принципиальные технологические схемы реализации процессов. Разработанные теоретические основы моделирования процессов очистки сточных вод адсорбцией природными и модифицированными сорбентами. Предложены математические модели для прогнозирования лимитирующей стадии процесса сорбции на основании теории локальной изотропной турбулентности для аппаратов с механическими устройствами - при расчете внешнедиффузионных параметров, а также внутридиффузионных параметров с использованием теоретических расчетов эффективных коэффициентов внутренней диффузии. Исследована сорбция Сs и Sг с жидких радиоактивных отходов на модифицированных глинистых минералах и установлены оптимальные условия процесса. Доказано, что в случае применения модифицированных глинистых сорбентов не наблюдается вторичное загрязнение воды металлами-модификаторами. Проведена идентификация экспериментальных данных адсорбции радионуклидов существующим теоретическим изотермам сорбции. Исследованны аспекты использования жидкостной хроматографии в промышленных условиях для разделения смеси органических растворителей. Решения адсорбционной модели использованы для прогнозирования конкурентного равновесия адсорбции раствора и активного компонента подвижной фазы на основе изотерм адсорбции, а стандартные изотермы адсорбции определенные на основании дополнительных данных адсорбции, измеренных в инертной системе. Предложена принципиальная технологическая схема хроматографического разделения смеси органических растворителей. Основные результаты переданы для внедрения в производство и используются в учебном процессе.
On the basis of theoretical and experimental investigations of the acid modification bentonite developed adequate mathematical model, calculated values of the kinetic coefficients and the proposed process flow diagram the process. The theoretical basis of modeling processes of cleaning liquid media by adsorption of natural sorbents. The proposed mathematical model of the process to establish the rate-limiting step by calculating external diffusion parameters (based on the theory of locally isotropic turbulence for vehicles with mechanical devices) and internal diffusion parameters (using theoretical calculations of effective internal diffusion coefficient). Investigated the adsorption of Cs and Sr on the modified clay minerals and optimum process conditions. Proved that in the case of the modified clay adsorbents is observed secondary pollution of water modifier metal. Identified on the experimental data of adsorption of radionuclides existing theoretical sorption isotherms. Studied aspects of liquid chromatography in industrial conditions for separating a mixture of organic solvents. Solutions of the adsorption model used to predict the competitive equilibrium adsorption solution and the active component of the mobile phase on the basis of the adsorption isotherms, and the standard adsorption isotherms determined on the basis of additional data of adsorption measured in an inert system. A basic flow diagram of chromatographic separation of a mixture of organic solvents. Main results released for implementation in production and use in the classroom.

The thesis explored the use of different sorbent materials in solid phase extraction method development. The methods included the use of the polymeric Agilent Bond Elut Plexa solid phase extraction and electrospun polymer-silica composite sorbents for clean-up and preconcentration. Sample clean-up for alkaloids (hydrastine and berberine) in goldenseal, Hydrastis canadensis and flavonoids (quercetin, kaempferol and isorhamnetin) in Ginkgo biloba was achieved using Bond Elut Plexa SPE sorbent. Clean-up of flavonoids in Ginkgo biloba was also achieved using electrospun polymer-silica composite (polystyrene-silica, polyacrylonitrile-silica and nylon 6-silica) sorbents. All analysis of flavonoids and alkaloids was carried out using an Agilent 1200 Series HPLC coupled with a diode array detector. Good peak separation was achieved in less than 6 min employing an Agilent ZORBAX Eclipse Plus C18 column (4.6 x 75 mm, 3.5 μm) at 35⁰C. The mobile phases employed were 0.1% phosphoric acid/methanol gradient and 0.5% phosphoric acid/methanol (40:60) for alkaloids and flavonoids respectively. The calibration curves exhibited linearity up to 120 μg mL⁻¹ with correlation coefficients of more than 0.9980. The recoveries ranged from 73-109% with relative standard deviation of less than 5% for all analytes. Agilent Chem Elut supported liquid extraction was employed for the development of a sample preparation method for the determination of 24 banned aromatic amines from azo dyes in textile following the EU standard method EN 14362-1:2003 (E) and the Chinese standard method GB/T 17592-2006. The supported liquid extraction was effective in the extraction of the aromatic amines from textile (cotton, wool and polyester/cotton [80%:20%]). Most of the recoveries obtained were conforming to the minimum requirements set in the EN 14362-1:2003 (E) standard method and the relative standard deviations were less than 15%. Good peak separation was obtained within 70 min run time using the Agilent Zorbax SB-Phenyl column (4.6 mm x 250 mm, 5-micron) or the Agilent DB-35 MS (J & W) (30 m x 0.25 mm, 0.25 μm film thickness. It was demonstrated that the polymeric Agilent Bond Elut Plexa, electrospun nanofibers and diatomaceous earth were effective in extraction of alkaloids, flavonoids and aromatic amines in different matrices. The developed methods were simple, rapid and reproducible.

El desenvolupament de diferents materials per a les tècniques d’extracció mitjançant processos de sorció és una àrea en continua expansió; no obstant, l’extracció d’anàlits polars encara és un tema que requereix més investigació. En aquesta Tesi s’han desenvolupa nous materials que reuneixen de selectivitat i/o capacitat característiques per a extreure contaminants orgànics polars en mostres aquoses. La primera part descriu el desenvolupament de nous materials polimèrics que milloren la capacitat i selectivitat de l’extracció en fase solida, i hi inclau els polímers altament entrecreuats amb caràcter hidrofílic, els sorbents altament entrecreuats d’intercanvi iònic de mode-mixte i els líquids iònics suportots en fases polimèriques; així com la seva avaluació com a nous sorbents per a la extracció de contaminats polars en diferents mostres aquoses mediambientals seguit de l’anàlisi per LC. La segona part está centrada en la preparació de noves barres agitadores amb recobriments monolítics polars i la seva posterior aplicació per l’extracció d’analits polars en diferents aigües de procedéncia mediambiental.
The development of different materials for sorptive extraction techniques is a continuously evolving field of research. Although there have been significant developments in this area, the extraction of polar analytes is still considered the bottleneck of the extraction process. The efforts have been undertaken to improve capacity and selectivity. For this reason, one of the main objectives of this Thesis is to develop new materials to extract polar organic contaminants from water samples. The first part reports on the development of new polymeric materials for solid-phase extraction including hypercrosslinked polymers with hydrophilic character, mixed-mode ion-exchange hypercrosslinked sorbents and supported ionic liquid polymeric phases and their evaluation as SPE sorbents for the extraction of polar contaminants, followed by LC analysis. The second part is focused on the preparation of new stir bars with polar monolithic coatings and their application to stir bar sorptive extract polar analytes from environmental water samples.

Como resultados de los análisis de los materiales carbonosos y en base lo encontrado en la literatura (propiedades) se eligieron tres materiales carbonosos (MC 500, MC600 y MC 700) para evaluar la capacidad de sorción con una solución bimetálica de cadmio y cromo. Primero se realizo la cinética de sorción para determinar el tiempo de equilibrio y el porcentaje remoción de cada uno de los metales. Posteriormente, los datos experimentales obtenidos los tres materiales carbonosos se ajustaron a los diferentes modelos cinéticos linealizados (primer orden, segundo orden y pseudo- ecuación de segundo orden) para conocer el tipo de adsorción que se lleva acabo,
En este trabajo de investigación se obtuvieron 5 materiales carbonosos provenientes de la pirólisis de lodos residuales a diferentes temperaturas 400, 500, 600, 700 y 750 ºC basados en el análisis termogravimétrico (TGA) y térmico diferencial (DTA) del lodo residual seco, el incremento en la temperatura de pirólisis le confirió al material carbonoso diversas propiedades estructurales, morfológicas y texturales. Estas variaciones en las propiedades se determinaron a partir de las siguientes técnicas: Micronanalisis elemental por Dispersión de Energía de Rayos-X (EDS), Espectroscopia Infrarroja (IR), Microscopia Electrónica de Barrido (MEB) y Fisisorción de Nitrógeno.
UAEM

Depuis plusieurs années de nouveaux procédés industriels destinés à la réfrigération et à la climatisation sont étudiés et mis sur le marché. Parmi ceux qui commencent à connaître des débouchés commerciaux on compte les systèmes utilisant des fluides frigoporteurs diphasiques solide/liquide. Ces dispositifs offrent en effet les avantages de réduire l’utilisation des fluides frigorigènes de plus en plus réglementée et de pouvoir lisser la production de froid sur 24 heures grâce à la possibilité de stocker ces fluides diphasiques. Le domaine de la réfrigération connaît au niveau européen, grâce à plusieurs industriels, un premier essor de l’utilisation de « coulis » ou « sorbet » de glace. La climatisation industrielle ou collective représente également un enjeu énergétique majeur tant du point de vue de la consommation énergétique instantanée qu’elle nécessite que du point de vue des “pics” qu’elle génère à certaine périodes de la journée.Dans ce domaine et sur le continent asiatique (particulièrement au Japon), l’utilisation de sorbets est également en phase d’expansion. Dans ce cas, les sorbets utilisés sont des « coulis d’hydrates » qui présentent l’intérêt de cristalliser à des températures positives plus adaptées à la climatisation que celles des « coulis de glace ».Ces travaux de thèse ont donc consisté à adapter une technologie de réfrigération disponible sur le marché européen au domaine de la climatisation. Le fluide utilisé est une solution de TBAB (Bromure de Tetra-ButylAmmonium) qui est une solution aqueuse dont la température de cristallisation à pression atmosphérique peut être ajustée entre environ 6 et 12°C. Le dispositif expérimental conçu et construit est donc un prototype industriel de taille réelle capable de climatiser 4 pièces. A la fois démonstrateur industriel et banc d’essais instrumenté, il est destiné à mener à bien des séances d’essais afin de démontrer la faisabilité du procédé, de diagnostiquer des améliorations et de prévoir de nouvelles évolutions. Parallèlement aux travaux de construction et aux séances d’essais, des mesures complémentaires concernant certaines caractéristiques thermo-physiques des sorbets d’hydrates de TBAB ont été menées en laboratoire. Enfin, un outil de modélisation a également été développé afin de rattacher les expériences à des phénomènes thermo-physiques théoriques. Cette modélisation a pour but d’être un outil prédicatif à la conception de nouvelles installations et au développement du prototype
For some years, new industrial processes have been developed and marketed in the refrigeration and air conditioning fields. Among systems which begin to have good business opportunities some are using two-phase secondary refrigerants solid / liquid. This kind of technology offers the advantages of reducing the use of classical refrigerants which are regulated and can smooth the production of cold over 24 hours with its ability to store the slurry. At the European level, thanks to the efforts of several manufacturers, the refrigeration field is developing fast with respect to the use of ice slurries. Moreover the industrial or district air conditioning field is a major energetic issue in terms of the immediate energy it requires as well as in terms of "peaks" generated during certain periods of the day.In this field, especially in Japan, the use of “PCM” (Phase Change Material) is additionally developing. In this technological segment, the PCM used are hydrate slurries. This solution has the advantage of crystallizing at positive temperatures which is more suited for the air conditioning than ice slurries.This research work deals with the adaption of a refrigeration technology available on the European market to the field of air conditioning. The fluid used is an aqueous solution of TBAB (Tetra-Butylammonium Bromide) with a crystallization temperature at atmospheric pressure which can be adjusted to a temperature between 6 and 12°C. The experimental device designed and installed is a real size prototype able to cool 4 rooms. Both the industrial demonstrator as well as instrumented test bench allowed us to carry out practice sessions which demonstrated the feasibility of the process. It also allowed us to design improvements and new developments. In parallel to the construction and the experiments, additional measurements concerning some thermo-physical characteristics of TBAB hydrate slurries were conducted in specialised laboratory. Finally, a modelling tool was also developed in order to relate our experiments with theoretical thermo-physical phenomena. This numerical model is intended to be a predicative tool for the design of new installations and for the development of the prototype

碩士
國立中興大學
化學系所
104
In this study, we have developed a new material ‘Graphene based acrylic resin composite sponge material’ as sold phase extraction sorbent material for the extraction of triazine herbicides in aqueous solution and determination by HPLC-UV. The adsorption capacity of acrylic resin material was enhanced by adding graphene nanosheets as fillers. This composite sponge material was prepared by mixing of graphene oxide, acrylic resin, cross-linking agents and foaming agents and then inflated with air to foam by Frother. And the foam material was heated at two stages to obtain Graphene/Acrylic resin based Composite Sponge Material. In the extraction procedure, the sponge material was placed into the syringe and sample solution was aspirated into the syringe barrel for rapid adsorption/extraction. Then the adsorbed analytes were desorbed using organic solvent, and dried by nitrogen, then re-dissolved with 100 μL acetonitrile for HPLC-UV analysis. In order to obtain the best extraction efficiency, the parameters affecting the conditions including graphene content, the pH of sample solution, the salt addition and desorption solution were investigated thoroughly. Under the selected conditions, composite sponge materials were synthesized with 15 mg of graphene and 1 mL acrylic resin solution. 10 mL of aqueous solution (pH 7) was used for sample loading and followed with elution using 3 mL acetone. Under the optimal conditions, the limit of determination (LOD) and limit of quantitation (LOQ) for five triazine herbicides were between 0.3 ng/mL and 0.9 ng/mL. The relative standard deviations (RSD) were less than 3%. Recoveries were ranged between 82.8 % - 107 %. The total sample preparation steps were taken only 10 minutes. These results indicated that the Graphene/Acrylic resin Composite Sponge Material based solid phase extraction method is a rapid, sensitive, easy to handle and eco-friendly sample preparation method.

碩士
國立中興大學
化學系所
104
This study demonstrates a simple and rapid method for the preparation of graphene based in-pipette tip monolithic micro solid phase extraction (μSPE) sorbent via an improved sol-gel technique using polyethylene glycol (PEG) as porogenic material. For the first time, the prepared graphene sol-gel based in-pipette tip monolithic μSPE sorbent was applied for the analysis of UV filters in environmental water samples and in cosmetics (as target compounds) using HPLC-UV. The graphene sol-gel in-pipette tip monolith was prepared by mixing appropriate amounts of graphene oxide (GO, a stationary phase sorbent) and tetramethyl-orthosilicate (TMOS, a sol-gel precursor), tetraethyl orthosilicate (TEOS, as a co-precursor), polyethylene glycol (PEG-6000, a sol-gel active organic polymer), and pyridine (as sol-gel catalyst) in the 20 mL glass vial. Then, the mixture solution transferred into plastic pipette tip and kept at hot air-oven (50°C) for polymerization. After the polymerization, the sorbent materials were washed with methanol, 0.01% HCl solution and pure water to remove un-reactants. After that, the prepared in-pipette tip sorbent material was immersed in 0.5% hydrazine solution for the reduction of graphene oxide to graphene. And then, the material was immersed in 10% dichlorodimethylsilane solution for the silicon alkylation. PEG was used to lengthen the sol-gel network and to improve the structure rigidity and permeability (porosity) of the prepared monolithic sorbent material. For the extraction of UV filters, important parameters that influence the extraction efficiencies were thoroughly investigated and optimized. Under the optimal conditions, the limit of determination (LOD) and limit of quantitation (LOQ) for four UV filters were below 0.05 ng/mL and 0.2 ng/mL, respectively. The relative standard deviations (RSD) were all less than 6.0 %. It only took less than 12 min for the total μSPE procedure. Recovery were ranged from 88.0-103.6 % and the RSDs were all lower than 6.2 %. Compared with traditional sol-gel preparation methods, this graphene sol-gel in-pipette tip monolithic method required less polymerization time (due to the usage of pyridine as base catalyst) and the synthesized material showed good permeability. Results showed that the proposed method is a simple, fast, sensitive and eco-friendly sample preparation method.

碩士
國立中興大學
化學系所
102
In this study, graphene modified silica microspheres was applied as a new sorbent material for on-line solid phase extraction (SPE) coupled to high-performance liquid chromatography with photodiode array detection (HPLC-PDA) for the determination of Alkylphenol (APs) and Bisphenol A (BPA) in environmental water samples. In this research, the carboxylic acid groups present on grapheme oxide (GO) were activated with EDC/NHS catalyst for amide bond formation with the silica microspheres. Then, the graphene functionalized silica composite (G@SiO2) was prepared through hydrazine reduction of GO bonded silica (GO@SiO2) composite under microwave irradiation. Surface morphology of the synthesized material was characterized using FT-IR and FE-SEM. In order to achieve the maximum extraction efficiency, various synthesis conditions were optimized including the concentration of EDC/NHS catalyst and the synthesis time; Furthermore, different parameters that affecting the extraction condition such as pH of the sample solution, volume of desorption solvent, loading rate of sample solution and salt effect. Experimental results indicate that 50mM EDC/NHS catalyst in GO solution (0.5 mg/mL), and the addition of 0.5 g of amine-modified silica microspheres under stirring for 12 hours shows the best synthesis results. Under the selected conditions, including 0.6 mL min-1 of loading rate of sample solution at pH 6 with no added of salt, 80μL of Acetonitrile as desorption solvent showed the maximum extraction efficiency for AP and BPA. Under the optimal conditions, the linear ranges were ranged between 0.5-50 ng/mL for AP and BPA in river water. The correlation coefficients were greater than 0.9962. Quantitation limits were lower than 0.26 ng/mL and the detection limits were lower than 0.08 ng/mL. The presented on-line SPE method was applied to the real water analysis and the relative recoveries were ranged from 81.6-101.6% for spiked analytes in river water samples. The experimental results exhibited that the presented method is a simple, rapid, convenient, efficient and eco-friendly sample preparation method for the determination of APs and BPA in environmental samples.

abstract: In this study, two novel sorbents (zeolite 4A and sodium polyacrylate) are tested to investigate if utilizing ultrasonic acoustic energy could decrease the amount of time and overall energy required to regenerate these materials for use in cooling applications. To do this, an experiment was designed employing a cartridge heater and a piezoelectric element to be simultaneously providing heat and acoustic power to a custom designed desorption bed while measuring the bed mass and sorbent temperature at various locations. The results prove to be promising showing that early in the desorption process ultrasound may expedite the desorption process in zeolite by as much as five times and in sodium polyacrylate as much as three times in comparison to providing heat alone. The results also show that in zeolite desorption utilizing ultrasound may be particularly beneficial to initiate desorption whereas in sodium polyacrylate ultrasound appears most promising in the after a temperature threshold is met. These are exciting results and may prove to be significant in the future as more novel heat-based cooling cycles are developed.
Dissertation/Thesis
Masters Thesis Mechanical Engineering 2018

Thesis (M.S.)--University of Wisconsin--Madison, 2002.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-82).

Chitosan-based copolymers (CH-GL1:6, CH-GL1:1, CH-GL1:0.5, and CH-GL1:0.25) were prepared at variable weight ratios of chitosan (CH) to glutaraldehyde (GL). Physiochemical properties of cross-linked copolymers were characterized using FTIR (Fourier Transform Infrared) spectroscopy, PXRD (Powder X-ray Diffraction), CHN analysis, and thermogravimetric analysis (TGA). The swelling behaviour of the polymers along with chitosan was investigated. The sorption properties of copolymers with arsenate oxoanions were investigated at various pH using 10 mM phosphate buffer systems and also in aqueous solution without buffer. The Sips sorption model describes the best fit parameters for adsorption. The relative monolayer sorption capacities Qm (mg/g) of the adsorbents are given in parentheses in the following order: CH-GL1:1(14.4) > CH-GL1:0.5(12.0) > CH-GL1:0.25(10.3) > CH-GL1:6(2.24). In general, the sorption capacities are listed in descending order as follow: un-buffered > buffered (pH 5.0) > buffered (pH 8.5). The removal efficiencies for 20 mg of polymers over a variable concentration range ( 1-200 mg/L) of arsenate in aqueous solution without buffer are as follow: CH-GL-1:1(20-95%), CH-GL1:0.5(14-97%), CH-GL1:0.25(10-98%), CH-GL1:6(2.0-56%), and CH (0.007-3.9%). The sorption properties of the adsorbents were also determined in bicarbonate buffer to evaluate the competitive effect of phosphate buffer on adsorption of arsenate oxoanions. X-ray absorption spectroscopy (XAS) of chitosan and CH-GL1:1 was performed after adsorption at different pH conditions using two buffer systems to evaluate the chemical environment around the arsenate species. In addition, sorptive properties of phenolic adsorbate (i.e. PNP) were estimated with CH-GL copolymers at various pH conditions. The estimated sorptive capacities (Qm; mmol/g) for PNP are in the range 0.07-0.21(mmol/g) while removal efficiencies for PNP are greater at lower pH conditions.

Physical activation of oil-sands fluid coke, a dense carbonaceous material, using sulfur dioxide (SO2) was investigated as a means of utilizing a plentiful and inexpensive waste for elemental mercury (Hg) removal. A new model was developed to elucidate physical activation of dense carbonaceous materials. Experiments and model simulations revealed that, during activation with SO2, a sulfur-rich porous layer is formed around the periphery of the coke particles; this porous layer reaches a maximum thickness as a result of diffusion limitations; the maximum porous layer thickness is controlled by activation conditions and determines the maximum achievable specific surface area (SSA). Pre-oxidation in air prior to activation, acid washing after activation and smaller coke particle size all result in higher SSA. The highest SSA achieved was 530 m2/g, the highest yet found for oil-sands fluid coke with physical activation. If present, oxygen out-competed SO2 for carbon during activation. SO2 activation and porous layer formation did not occur until oxygen was depleted. Sulfur added to coke through SO2 activation is mainly in reduced forms which are more thermally stable than elemental sulfur in commercial sulfur-impregnated activated carbons (SIACs). TGA and elemental analyses revealed that only 17% of sulfur was removed at 800°C from SO2-activated coke under inert conditions, compared with 100% from a commercial SIAC. The role of sulfuric acid (H2SO4) in vapor Hg capture by activated carbon (AC) was studied due to conflicting findings in the recent literature. In the absence of other oxidizing species, it was found that Hg could be oxidized by oxygen which enhanced vapor Hg adsorption by AC and Hg absorption in H2SO4 solution at room and elevated temperatures. At 200°C, AC treated with 20% H2SO4 reached a Hg loading of more than 500 mg/g, which is among the highest Hg capacities yet reported. When oxygen was not present, S6+ in H2SO4 was found to act as an oxidizer of Hg, thus enabling Hg uptake by H2SO4-treated AC at 200°C. Treating the AC with SO2 at 700°C improved the initial rate of Hg uptake, with and without subsequent H2SO4 treatment.

Thesis (MTech. degree in Mechanical Engineering)--Tshwane University of Technology, 2009.
South Africa produces 41.3 GWe per year of which 90% is coal-derived. During combustion of coal, sulfur contained in the fuel is converted to SO2. The gas poses a serious danger for the human and environmental health. The health hazards associated with SO2 include hair loss, throat inflammation, impaired vision and respiratory illnesses. Sulfur dioxide is also forms acid rain, which leads to acidification of soils, waterways and forests. The main objective of this investigation is to explore methods of increasing lime utilization using South Africa calcium/siliceous-based sorbents for the purposes of removal of SO2 in the Flue Gas Desulfurization (FGD) system. Consequently, this study presents experimental findings on the preparation, characterization and sulfation of locally available fly ash, calcium oxide (CaO) and bottom ash. CaO was obtained from calcination of limestone in a laboratory kiln at a temperature of 900 °C and CaO/fly ash sorbent prepared using an atmospheric hydration process.

Η απορρύπανση των υδάτων αποτελεί αναγκαία και καθιερωμένη από δεκαετίες πρακτική. Η απορρύπανση με τη μέθοδο της ρόφησης είναι μία από την πληθώρα των τεχνικών που εφαρμόζονται. Το περισσότερο διαδεδομένο ροφητικό υλικό είναι ο ενεργός άνθρακας, του οποίου όμως το υψηλό κόστος παραγωγής, οδήγησε την επιστημονική έρευνα στην αναζήτηση εναλλακτικών, υλικών χαμηλότερου κόστους. Για το σκοπό αυτό, το επιστημονικό ενδιαφέρον έχει στραφεί σε πολλά υλικά κυρίως οργανικής προέλευσης, αλλά και σε ανόργανα υλικά, όπως τα οξείδια των μετάλλων, τα οποία αφθονούν στη φύση. Στην παρουσα εργασία έγινε μελέτη της ροφητικής ικανότητας φυσικών οξειδίων, για τη ρόφηση αρωματικών οργανικών ενώσεων και βαρέων μετάλλων. Πιο συγκεκριμένα, μελετήθηκε ο μηχανισμός της ρόφησης του φαινανθρενίου, της 2-ναφθόλης και του υδραργύρου από οξείδια αργιλίου, τιτανίου, αργιλίου/πυριτίου και σιδήρου, με σκοπό την αξιολόγηση των υλικών αυτών ως ροφητικών υλικών και τη σύγκριση των αποτελεσμάτων με αυτά της ρόφησης των αντίστοιχων ρύπων από υλικά που παρασκευάζονται από την πυρόλυση πρώτης ύλης βιολογικής προέλευσης. Για τη μελέτη της κινητικής της ρόφησης του φαινανθρενίου και της 2-ναφθόλης πραγματοποιήθηκαν πειράματα σε θερμοκρασία περιβάλλοντος, σε θαλασσινό και γλυκό συνθετικό νερό, με διαφορετικές ποσότητες ροφητικού υλικού (χωρίς χημική επεξεργασία) και για διαφορετικό χρόνο επαφής. Από τα πειράματα αυτά μετρήθηκε η κινητική της ρόφησης καθώς και το ποσοστό απομάκρυνσης των ρύπων από το διάλυμα. Από τις μετρήσεις που έγιναν, προέκυψε ότι το ποσοστό απομάκρυνσης του φαινανθρενίου από το διάλυμα αυξάνεται αυξανομένης της ποσότητας του ροφητικού υλικού. Η σταθερά της ρόφησης Kd, κυμάνθηκε σε ένα εύρος τιμών από 1 έως 10 L/Kg, τιμές 2 έως 4 τάξεις μεγέθους μικρότερες από αυτές άλλων ροφητικών υλικών βιολογικής προέλευσης, ή προϊόντων πυρόλυσης. Τη μεγαλύτερη ικανότητα ρόφησης φαινανθρενίου επέδειξε η γ-αλούμινα με ειδική επιφάνεια 270 m2/g, με μέγιστη απομάκρυνση φαινανθρενίου το 55 % της αρχικής συγκέντρωσης έπειτα από 8 ημέρες, ενώ τη μικρότερη ικανότητα ρόφησης η γ-αλούμινα με ειδική επιφάνεια 120 m2/g, με μέγιστη απομάκρυνση το 14 % της αρχικής συγκέντρωσης, έπειτα από 10 ημέρες. Η τιτάνια, με ειδική επιφάνεια 120 m2/g, είχε ως αποτέλεσμα την απομάκρυνση του 52 % της αρχικής συγκέντρωσης φαινανθρενίου, σε 8 ημέρες. Από τα πειράματα ρόφησης της 2-ναφθόλης από την γ-αλούμινα, δεν προέκυψε μετρήσιμη ρόφηση. Η ρόφηση του υδραργύρου από την γ-αλούμινα (ειδική επιφάνεια 131 m2/g), και τα οξείδια σιδήρου μελετήθηκε με πειράματα στους 25 °C, σε pH 5 και με χρόνο εξισορρόπησης τις 24 h. Από τα πειράματα προέκυψε ισόθερμη καμπύλη και έγινε προσπάθεια προσαρμογής της σε μοντέλα ρόφησης. Παρατηρήθηκε αύξηση του ποσοστού απομάκρυνσης του υδραργύρου, με αύξηση της μάζας της γ-αλούμινας. Το μέγιστο ποσοστό απομάκρυνσης, ήταν το 93 % της αρχικής συγκέντρωσης και επιτεύχθηκε με μάζα γ-αλούμινας ίση και μεγαλύτερη από 1 g. Για τιμή Ce=15 mg/L, μετρήθηκε qe=0,91 mg/g, τιμή 1 έως 2 τάξεις μεγέθους μικρότερη από αυτές άλλων ροφητικών υλικών βιολογικής προέλευσης ή προϊόντων πυρόλυσης. Τα οξείδια σιδήρου, παρότι είχαν ειδική επιφάνεια 55 m²/g, δεν παρουσίασαν μετρήσιμη ροφητική ικανότητα για κανέναν από τους ρύπους, που μελετήθηκαν στην παρούσα εργασία. Συνοψίζοντας μπορούμε να πούμε ότι τα ανόργανα υλικά που μελετήθηκαν στην παρούσα εργασία, παρόλο που παρουσιάζουν μεγάλες τιμές ειδικής επιφάνειας, δεν μπορούν να χαρακτηρισθούν ως αξιόλογα ροφητικά υλικά, τόσο για τη ρόφηση των οργανικών ρύπων φαινανθρένιο και 2-ναφθόλη, όσο και για τη ρόφηση του υδραργύρου.
Water treatment is a necessary and standard practice since decades. Adsorption technology in water treatment is one of many techniques being used. Activated carbon is the most widely applied adsorbent in water treatment, however its high production cost has led scientific research to investigate alternative low cost sorbent materials. This need has developed scientific interest towards novel materials most of them derived from biomass, but also inorganic oxides that are abundant in nature. The present study focuses on the investigation of the capacity of natural oxides to adsorb aromatic organic compounds and heavy metals. Specifically, sorption of phenanthrene, 2-naphthol and mercury onto aluminum, titanium, silicon and ferric oxides was examined, for the evaluation of these materials as sorbents, compared to pyrolized biomaterials. For the study of sorption of phenanthrene and 2-naphthol, batch experiments were conducted at room temperature, using artificial seawater and fresh water, different mass of sorbent material at different contact time. Sorption kinetics and the pollutant removal percentages were determined. The proportion of phenanthrene removal increased with the increase of the mass of the sorbent material. Sorption distribution coefficient Kd ranged between 1 and 10 L/Kg. These values are 2 to 4 orders of magnitude lower than the respective values shown for biomaterials and for pyrolysis products, respectively. Maximum sorption capacity of phenanthrene (55 % proportion removal) was shown by γ-alumina, with a specific surface area equal to 270 m2/g, after 8 days. Minimum sorption capacity (14 % proportion removal) was shown by γ-alumina, with a specific surface area equal to 120 m2/g, after 10 days. Titania, with a specific surface area equal to 120 m2/g, adsorbed a proportion of 52 % of the initial concentration of phenanthrene, after 8 days. Sorption experiments of 2-naphthol from γ-alumina, did not show a measurable sorption. Sorption of mercury from γ-alumina and ferric oxides was studied, conducting batch experiments at 25 °C, pH 5, 24 h contact time. The experiments resulted to an isotherm curve that was evaluated using different sorption isotherm models. An increase of the proportion of mercury removal, with the increase of the mass of γ-alumina was observed. Maximum proportion of mercury removal (93% of the initial concentration) was observed with the addition of γ-alumina of 1 g or more. At Ce=15 mg/L, qe=0,91 mg/g was measured. This value is 1 to 2 orders of magnitude lower, than the respective values shown for biomaterials and for pyrolysis products, respectively. Even though ferric oxides’ specific surface area was estimated at 55 m²/g, they did not show a measurable sorption capacity for any of the pollutants tested in the present study. Even though the materials examined in the present study, were of large specific surface area, their sorptive properties shown, are not competitive with the respective properties of biomaterials. Thus, they cannot be considered as promising sorbents for the removal of phenanthrene, 2-naphthol, or mercury from water.

M.Sc.
With increasing industrial activities in South Africa, many of its waters are contaminated with both organic and inorganic pollutants. This is also a worldwide challenge which has resulted in an escalation in research efforts to combat it. Organic pollutants, for example, can be harmful to human health and the environment. Even when present at low concentrations, they tend to bio-accumulate and interact with endocrine systems. Therefore it is necessary that these pollutants are removed from effluents before they are integrated with water systems such as rivers and lakes. In an effort to utilize economic and efficient removal techniques, low cost and locally available materials have been used as potential adsorbents for the removal of these organic pollutants from synthetic wastewater. These coal-based materials were further fabricated into nanoporous sorbents through activation processes to improve their adsorption properties. The project reported in this dissertation was thus undertaken to explore, specifically, the efficacy of coal and coal-based sorbents (acid treated coal, activated carbon and activated fly ash) in their ability to remove phenolic compounds from wastewater.

This PhD Thesis in Chemical Sciences aims at a deep understanding of the intertwining among materials properties, experimental conditions and adsorption outcomes, with the focus on an experimental research activity dealing with the removal of two target pollutants that contribute to increase 1) outdoor pollution (hydrogen sulphide) and 2) indoor pollution (formaldehyde), by adsorption on materials of various nature.