Dissertations / Theses on the topic 'ORGANIC/ INORGANIC POLLUTANTS'

This research focuses on the synthesis, characterization, and capability of the metal organic frameworks (MOFs) as a candidate adsorbent for storage and separation of greenhouses gases. The performance and effectiveness of various synthesized MOFs were explored for the selectivity of CO2/N2 and CO2/CH4. The research contributes to the advances in synthesis of different MOFs and their application for gas uptake. This has potential advantages than other materials for future environmental science and materials applications.

This work is the first one conducted in Veneto region, Italy with collaboration of ARPAV including important organic (OC/EC and PAHs) and inorganic pollutants (trace elements), which were characterized for longer period of time in order to quantify the source contributions of PM2.5 at regional scale (Veneto) using receptor modelling [Factor Analysis]. 360 samples were collected from six major cities located in 6 Provinces during April 2012- February 2013. The results show that OC, EC, PAHs and Trace elements exhibited higher concentration during winter month in all measurement sites, suggesting that the stable atmosphere and lower mixing layer play important role for the accumulation of pollutant. Meteorological parameters especially wind velocity and temperature play significant role in pollutant accumulation from local sources. Finally, possible sources of particulate matter have been characterized using Conditional Bivariate Probability Function, diagnostic ratios and Factor Analysis and results indicated that biomass burning for household heating and cooking, followed by vehicular traffic, oil combustion and crustal are the main sources of particulate matter in Veneto region.

This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.

In recent years water contamination is reaching alarming levels, since the concentration of pollutants present in seas, lakes and streams has far exceeded water self-purifying capacity. The most widespread sources responsible for water pollution are urban and industrial dumps containing a vast range of dangerous substances. Despite wastewaters are always subjected to purification treatments, a complete remediation is not always possible. The most common pollutants are heavy metal ions and organic compounds such as phenolic compounds, polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pesticides and synthetic dyes. All these substances are highly stable and can easily bioaccumulate in living organisms as xenobiotic molecules, causing chronic and acute toxicity or carcinogenic and mutagenic effects. Furthermore, substances as dyes can cause changes to the aquatic ecosystem as they absorb the sunlight limiting its penetration into deep waters, thus inhibiting the photosynthesis of aquatic plants and thus limiting the water re-oxygenation capacity. In such a scenario, in the last few decades the scientific community has put a great deal of effort into the improvement of wastewater remediation processes. Among the various treatments, adsorption is one of the most useful thanks to its simplicity and low cost. The great advancement in nanotechnology has paved the way for new highly effective nanostructured adsorbent materials. These generally porous nanoadsorbents are characterized by a high surface area and high surface/volume ratio, which greatly influence their adsorption capacity. The purpose of this thesis work was the development of new mesoporous adsorbents, namely functionalized ordered mesoporous silica (OMS) and metal organic frameworks (MOFs) for the removal of heavy metal ions and organic dyes two types of pollutants commonly present in wastewaters.. Both OMS and MOFs are characterized by high surface area, high surface/volume ratio, geometrical order, and easy synthesis or functionalization. SBA-15 OMS and Fe-BTC type MOF have been successfully synthesized and characterized by means of different techniques, such as small angle X rays scattering (SAXS), powder X-rays diffraction (XRD), N2 physisorption, transmission and scanning electron microscopy (TEM and SEM), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). SBA-15 was functionalized with two different organic ligands, namely triethylenetetramine (TETA) and 2,8-dithia-5-aza-2,6-pyridinophane macrocycle (PyNS2), to obtain two different adsorbents, named SBA-TETA and SBA-PyNS2 which have been tested against some heavy metal ions (Cu2+, Zn2+ and Cd2+). The Fe-BTC, without further modifications, was instead tested as an adsorbent of two highly toxic organic dyes, such as Alizarin red S (ARS) and Malachite Green (MG). All adsorption experiments were monitored using Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES) or UV-Vis Spectroscopy. This allowed the experimental determination of the adsorption capacity q of the three adsorbents, their thermodynamic and kinetic parameters. In the case of SBA-15-based adsorbents, further investigations on their properties were carried out by means of potentiometric titrations.

Silver nanoparticle (AgNP) was synthesized using a medicinal plant Acalypha wilkesiana leaf extract through bottom-up approach. synthesis of nanoparticle via green route is simple, easy to handle and inexpensive in comparison of physical and chemical methods. Phytochemical screening of Acalypha wilkesiana determines the presence of coumarins, flavonoids, sterol, tannin, phenol and saponin. Synthesis of nanoparticle were detected at regular intervals with proper characterization technique majorly include UV-Vis spectroscopy. Further characterization involves the Scanning Electron Microscopy/ Transmission Electron Microscopy (SEM/TEM) which determines the size and shape of the nanoparticle. Fourier transform infrared spectroscopy helps in finding the biochemical function group of plant extract which serves as reducing and capping agent in nanoparticle synthesis. And crystal nature of nanoparticle was analysed via X-ray diffraction (XRD). Here we aimed the remediation of polluting aqueous solution via green route of silver nanoparticle synthesis and study the photocatalytic activity of organic dyes and ability to detect the toxic metal like Pb, As, Ni, Hg, Cr, Co, Fe, Mn, Pd and Se.

Philosophiae Doctor - PhD
Organic and inorganic pollutants are two broad classes of pollutants in the environment with their main sources from waste waters that are indiscriminately dumped from chemical related industries. Among the organic pollutants are dyes that come as effluents from the textile industries. Toxic metals are the main inorganic pollutants with their sources from industries such as mining, electroplating, batteries etc. The presence of both classes of pollutants in the aquatic environment poses a serious threat to aquatic organisms and humans who depend on these waters for domestic purpose. Therefore, this research focused on the fabrication of materials and designing of methods for removal of both classes of pollutants from their aqueous solutions.

Water pollution is one of the most serious environmental problems the world faces today. Due to a progressive change in environmental perception in developed countries, great attention is currently given to specific pollutants, both of natural and human origin, often labeled as organic and inorganic micropollutants. Micropollutants can have severe implications both on ecology and human health even in very low concentration in water, being potentially toxic and carcinogenic, and are included in the EU PP (Priority Pollutants) list. The current water purification treatments are affected by many limitations and do not significantly lower the concentration of micropollutants, unless the treatment is carried out, if technically possible, to such an extent to become not economically sustainable. In this context, the aim of this PhD thesis is the development and characterization of polymeric absorbing materials for the quantitative and reversible removal of organic and inorganic micro-pollutants from water. These materials are based on poly(amidoamine)s (PAAs), cyclodextrins and renewable resources such as guar gum and hemicelluloses. The synthetic procedures adopted are simple, eco-friendly and employ water as solvent. The materials proved able to absorb either inorganic (Cu(II), Co(II), Cd(II), Pb(II), Mn(II), Zn(II), Fe(II), Ni(II), Cr(VI)) or organic micropollutants (chloroform, halothane, tetrachloroethylene, o-toluidine) and were competitive with other sorbents reported in literature. They could also be regenerated and recycled without loss of absorption performance.

Graphitic carbon nitride (g-C3N4) heterojunction composites with the semiconducting metal oxides, CeO2, ZnO and TiO2 are prepared in situ by co-calcination of the precursor materials or by a solvothermal method. The structural, morphological and the optical properties of the prepared materials are studied using various microscopy and spectroscopy techniques. The synthesized composite materials, CeO2/g-C3N4, ZnO/g-C3N4 and TiO2/g-C3N4 are more efficient in the photocatalytic degradation of the water pollutants indigo carmine (IC) and atrazine than the pure metal oxide, g-C3N4, or their physical mixtures. The CeO2/g-C3N4 and ZnO/g-C3N4 composites also exhibit improved degradation efficiencies of atrazine as compared to the individual metal oxide or g-C3N4 materials. The improved photocatalytic activity of the composites are attributed to the effective electron-hole charge separation within composite heterojunction, resulting from the well matched energy levels of the metal oxide and g-C3N4. This strategy could be helpful for the synthesis of other metal oxide and g-C3N4 composites for photocatalytic applications.

Philosophiae Doctor - PhD
The increasing evidence of chemicals of emerging concern (CECs) in water bodies is causing major concern around the world because of their toxicological effects upon humans and aquatic organisms. The release of wastewater to the aquatic environment is most likely to introduce some trace levels of organic contaminants, some of which may be toxic, carcinogenic, or endocrine disruptors, as well as, persistent in the environment. These compounds are often persistent but not regularly monitored because they are mostly still excluded from environmental legislation. Their fate and persistence in the environment are not well understood.
2022-02-24

Philosophiae Doctor - PhD
The increasing evidence of chemicals of emerging concern (CECs) in water bodies is causing major concern around the world because of their toxicological effects upon humans and aquatic organisms. The release of wastewater to the aquatic environment is most likely to introduce some trace levels of organic contaminants, some of which may be toxic, carcinogenic, or endocrine disruptors, as well as, persistent in the environment. These compounds are often persistent but not regularly monitored because they are mostly still excluded from environmental legislation. Their fate and persistence in the environment are not well understood

L’océan Austral est soumis à la redistribution globale des contaminants par les voies atmosphérique et océanique. Cependant, la contamination des écosystèmes austraux est très peu connue, en particulier dans le secteur Indien. De par leur toxicité, leur mobilité et leur capacité à se bioaccumuler dans les tissus des organismes et à se bioamplifier dans les réseaux trophiques, le mercure (Hg) et les polluants organiques persistants (POPs) comptent parmi les contaminants les plus préoccupants. Du fait de leur position élevée dans les réseaux trophiques, les oiseaux marins sont exposés à de grande quantités de contaminants par la voie alimentaire. En conséquence, ils sont souvent utilisés comme bioindicateurs de l’état de contamination des écosystèmes, par le biais des plumes et du sang, qui peuvent être échantillonnés de façon non destructive. Ma thèse s’est intéressée aux nombreuses espèces d’oiseaux marins (plus de 40) qui nichent au sein des Terres Australes et Antarctiques Françaises, au sud de l’Océan Indien, afin de décrire et expliquer les niveaux de contaminants le long d’un large gradient latitudinal, de l’Antarctique à la Zone Subtropicale, et d’identifier les meilleures espèces bioindicatrices pour un suivi à long terme de la contamination de ces écosystèmes. Au cours d’une première étape méthodologique, les manchots et les poussins de toutes les espèces ont été identifiés comme de bons bioindicateurs de contamination puisque, à la différence de la plupart des oiseaux adultes, ils présentent une faible variabilité des niveaux de contaminants dans les plumes. Au cours d’une seconde étape explicative, l’effet de facteurs intrinsèques (traits individuels) et extrinsèques (écologie alimentaire déduite grâce à la méthode des isotopes stables) sur les niveaux de contaminants a été évalué dans les plumes des oiseaux de la communauté de Kerguelen (27 espèces) et dans le sang du grand albatros de Crozet (180 individus dont les traits de vie sont connus). L’écologie alimentaire s’est avérée être le principal facteur explicatif des niveaux de contaminants, tandis que l’âge, le sexe, la phylogénie et le statut reproducteur jouent un rôle mineur. La classe d’âge est néanmoins un facteur à prendre en compte, puisque les poussins montrent souvent des concentrations inférieures aux adultes. Au cours d’une troisième étape, les variations spatio-temporelles de la contamination ont été étudiées en utilisant une sélection d’espèces bioindicatrices et en tenant compte de leur écologie alimentaire. Plusieurs résultats portant sur différentes espèces (oiseaux océaniques) et populations (poussins de skua) ont montré que, contrairement aux prédictions, l’exposition des oiseaux au Hg augmente graduellement des eaux antarctiques aux eaux subantarctiques puis aux subtropicales, alors que l’exposition aux POPs, en accord avec la théorie de la distillation globale, montre la tendance inverse. D’autre part, la comparaison des concentrations en Hg dans les plumes de manchot, effectuée entre des spécimens de musée et des échantillons actuels, indique que leur exposition au Hg n’a pas changée depuis les années 1950-1970. Toutefois, des espèces subantarctiques montrent une tendance à la hausse. De futures études devraient viser à l’utilisation des plumes comme tissu de référence pour l’évaluation et le suivi de la contamination des écosystèmes, en particulier en ce qui concerne les POPs. Parmi les nombreuses espèces étudiées au cours de ces travaux de thèse, les bioindicateurs les plus pertinents se révèlent être le manchot empereur et le pétrel des neiges (Antarctique), le manchot royal, le pétrel bleu et l’albatros à sourcil noirs (subantarctique), le gorfou sauteur subtropical et l’albatros à bec jaune (subtropical). Le suivi à long terme de ces espèces permettra d’évaluer l’évolution temporelle de l’état de contamination de l’océan Austral
Antarctic and subantarctic marine environments are reached by inorganic and organic contaminants through ocean circulation and atmospheric transport. Yet, environmental contamination is poorly known in the Southern Ocean, in particular in the Indian sector. Among environmental contaminants, mercury (Hg) and persistent organic pollutants (POPs) are primarily of concern, because they are toxic, highly mobile, and they bioaccumulate in the tissues of living organisms and biomagnify up the food web. Seabirds, as upper predators, are exposed to large quantities of contaminants via food intake and have widely served as biomonitors of marine contamination, notably through the non-destructive sampling of their feathers and blood. My doctoral work has focussed on the abundant and diverse seabird species (more than 40) breeding in the French Southern and Antarctic Lands, southern Indian Ocean, in order to describe and explain contaminant concentrations over a large latitudinal gradient, from Antarctica to the subtropics, and to identify the best bioindicator species for contaminant biomonitoring. In a first methodological step, seabirds with synchronous moult of body feathers (adult penguins and chicks of all species) were recognised as good candidates as bioindicators, because, unlike most adult birds, they present low within-individual variation in feather contaminant concentrations. In a second explanatory step, the influence of intrinsic (individual traits) and extrinsic factors (feeding ecology inferred from the stable isotope method) driving variation in contaminant concentrations was evaluated in feathers of the large avian community of the Kerguelen Islands (27 species) and in blood of wandering albatrosses from the Crozet Islands (180 birds of known individual traits). Feeding ecology was the main factor driving variation in contaminant concentrations of blood and feathers, both at the community, population and individual levels, whereas age, sex, phylogeny and breeding status played a minor role. Age-class was however an important intrinsic factor to consider, with chicks usually having lower concentrations than adults. In a third step, spatio-temporal patterns of contamination were studied through selected bioindicator species and by taking into account their feeding habits. Results from different species (oceanic seabirds) and populations (skua chicks) showed that, contrary to predictions, Hg exposure gradually increases from Antarctic to subantarctic and subtropical waters, whereas, in accordance with the global distillation theory, POPs exposure has the opposite pattern. Comparisons between penguin feathers from museum collections and contemporary samples showed that bird exposure to Hg is overall not different today when compared to 50-70 years ago, but subantarctic species are possibly experiencing an increasing trend. Future research efforts should be focussed on the use of feathers as biomonitoring tools, in particular for POPs determination. The best recommended bioindicator species include the emperor penguin and snow petrel (Antarctic), king penguin, blue petrel and black-browed albatross (subantarctic), and northern rockhopper penguin and Indian yellow-nosed albatross (subtropical). Future biomonitoring studies on these species will give invaluable insights into the poorly-known temporal trends of environmental contamination in the Southern Ocean

The first of a series of mass mortalities of Nile crocodiles in the Olifants and Letaba rivers in the Kruger National Park (KNP) was reported in the winter of 2008. The present study investigated the levels and possible effects on eggshell thickness of inorganic elements and organic pollutants in Nile crocodile eggs from these rivers, and comparing them with eggs from a reference crocodile farm and a reference dam inside the KNP. The egg contents were analyzed for chlorinated organic compounds and brominated flame retardants. Eggshells and egg contents were analyzed for inorganic elements. The elemental concentrations in the eggshells and contents were low when compared with previous studies. The highest concentrations were found in the eggs from the reference crocodile farm. The eggs from the reference dam and the crocodile farm had thicker shells, and the eggs from the Olifants and Letaba rivers had thinner shells. Not all eggs in a female develop at the same rate, while eggshell formation presumably occurs at the same time for all eggs. As a result, the elemental profile of egg contents may differ between eggs of the same clutch, but less so for the shells. Weak or no associations were found between the elemental concentrations of the content and eggshells and eggshell thinning. A possible organic pollutant–induced eggshell thinning effect was found. The compounds found were not at levels that could have caused the mortalities, but may affect the sex ratios through endocrine disruption. Further studies are therefore required.
Thesis (M.Sc (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

In der vorliegenden Arbeit wurde mit Hilfe von Gefäßversuchen der Transfer von ausgewählten organischen (m-Kresol, Simazin, Lindan, Anthracen, Galaxolid) und anorganischen Umweltschadstoffen (As, Cd, Pb, Cr, Zn, Ni) aus dotiertem Substrat in Nutzpflanzen (Tomaten, Paprika) untersucht. Zum besseren Verständnis des Schadstofftransfers der organischen Verbindungen und als Möglichkeit einer kosten- und zeitsparenden Alternative zu den herkömmlichen Untersuchungsverfahren, wurden ergänzend in vivo – Experimente durchgeführt. Weitere Schwerpunkte der Arbeit waren Untersuchungen zur Schadstoffaufnahme durch Pflanzen in Abhängigkeit von der Substratkonzentration sowie der Vegetationsdauer. Ein weiterer Schwerpunkt der Arbeiten waren Studien über mögliche Einflüsse eines neuartigen Bodenverbesserungsmaterials auf die Schadstoffmobilität und Bioverfügbarkeit der oben genannten potentiellen Schadstoffe sowie die damit verbundene mögliche Aufnahme durch die Untersuchungspflanzen.

Le dragage de sédiments marins produit des millions de tonnes de déchets chaque année qu’il faut gérer durablement. Les deux sédiments étudiés, conservés dans des conditions anoxiques sous eau (sédiment brut), et oxiques soumis à l’altération naturelle (sédiment vieilli), présentent une contamination élevée en cuivre, plomb et zinc prépondérante surtout dans les fractions fines. Des phases réactives ont été identifiées telles que sulfures et matière organique, auxquelles le cuivre et le zinc sont en grande partie liés. Un dispositif expérimental innovant couplant un test de consommation d’oxygène à une colonne de lixiviation a été développé ; il a permis de mettre en évidence la réactivité des sulfures encore présent dans le sédiment vieilli malgré les conditions de stockage à l’air ambiant. La composante biologique a été étudiée également, à travers un test qualitatif mesurant l’impact des bactéries sulfo- et ferrooxydantes sur les paramètres pH et Eh des sédiments. Malgré l’importante concentration en carbonates conférant un pouvoir de neutralisation élevé, la communauté des bactéries neutrophiles sulfooxydantes a été capable d’abaisser le pH jusqu’à 4,5 – 5 unités. Cette réactivité a été contrôlée en soumettant les sédiments à un traitement de stabilisation-solidification avec des liants hydrauliques. L’évaluation environnementale par des tests cinétiques en mini-cellules d’altération et des tests de lixiviation en monolithe a démontré la bonne stabilisation des éléments métalliques pour les deux sédiments. Leur valorisation en mortiers cimentés a donc été envisagée. L’étude de la résistance mécanique de la substitution du sable par les sédiments entiers a montré la mauvaise résistance mécanique. En revanche, après application d’un traitement d’enlèvement de la fraction fine contaminée, la résistance s’est montrée satisfaisante pour des applications non-structurantes et constitue ainsi une filière de traitement et de valorisation pertinente dans la gestion de sédiments
Millions of tons of sediments are dredged every year leading to a need for a sustainable management. Both studied sediments, stored in anoxic conditions under a layer of water (raw sediment), and in oxic conditions submitted to natural weathering (weathered sediment), showed high contamination of copper, lead and zinc, concentrated mainly in the finer fraction. Reactive phases such as sulfides and organic matter were observed, with which copper and zinc are partially linked. An innovative experimental set-up coupling an oxygen-consumption test with a column leaching test has been developed; this set-up highlighted the sulfides reactivity which is still occurring in the weathered sediment, despite years of natural aging. The biological component of this reactivity has been also studied, through a qualitative assessment of the impact of iron- and sulfur-oxidizing bacteria on pH and Eh of sediments. Although high amount of carbonates responsible for important neutralization potential were detected, bacterial community of neutrophilic sulfur-oxidizing bacteria has been able to lower the pH until 4.5 – 5 units. This reactivity is controlled by submitting both sediments to a stabilization/solidification treatment with hydraulic binders. Environmental assessment with kinetic test in weathering cells and monolithic leaching test demonstrated that trace metals appear well stabilized for both sediments. Thus, their valorization in cemented mortars has been assessed. When total sediments were fully substituted to sand, they showed poor mechanical strength. However, when a sieving treatment for removing of the fine contaminated fraction was applied, the sediments mortars revealed good mechanical strength for use in non-structural applications. This research confirmed thus that the reuse of the coarser fraction of a marine sediment, raw or weathered, offered an efficient and interesting way of treatment and valorization

碩士
國立宜蘭大學
環境工程學系碩士班
106
In this study, the granulation method involving high-temperature sintering of ferro-carbon is used to investigate the feasibility of its degradation and adsorption, and the effects of subjecting it to aeration. The method involves uniformly mixing appropriate proportions of iron powder, activated carbon, calcium stearate, and glass powder before granulation in a compressor and sintering via aeration using high-temperature nitrogen. The ferro-carbon is applied to the adsorption of phosphate in water and tested using isothermal and dynamic experiments, and the effects of pH values are investigated. The material is also applied to the degradation of reactive black 5 (RB-5) dye in water and thereafter tested through the optimal pH and columnar adsorption experiments, and under dynamic experimental conditions. The aforementioned experiments are used to understand the characteristics of ferro-carbon in relation to the removal of inorganic and organic pollutants in water. The optimum pH conditions for the removal of phosphate and RB-5 using ferro-carbon are pH 4 and pH 3, respectively. The adsorption behavior of ferro-carbon during phosphate removal complies with the Langmuir adsorption model, with the maximum adsorption amount (Qm) of phosphate estimated to be 14.77 mg g-1 at 40 °C. It is determined through the dynamic adsorption experiment that the adsorption reaction is consistent with the pseudo second-order adsorption model, and the activation energy is 6.08 kJ mol-1. The results indicate that the reaction is physical adsorption. The ferro-carbon has the best desorption effect in 1.5 M sodium hydroxide. The regeneration experiment reveals that its efficiency attenuates by 50% after 5 cycles. For removal of the RB-5 dye, the columnar adsorption experiment indicates a substantial decline in the removal of total organic carbon in the first 120 min. It is determined that adsorption and degradation may have occurred simultaneously during the first 180 min. The degradation reaction occurred after 120 min, whereas gradual removal occurred after 180 min. The oxidation–reduction (redox) potential during the columnar experiment reveals that a continuous redox reaction generates countless small electric fields, which in turn cause continuous degradation. The effectiveness of the ferro-carbon is observed to be significantly enhanced after another round of aeration. The dynamic experiment shows that the degradation process is consistent with the second-order reaction model. The adsorption rate constant of the material at 10, 25, and 40 °C is 0.0035, 0.0039, and 0.0044 mmol-1 dm3 s-1, respectively.

Ph.D.
This study explored the possible application of a relatively new electrode called exfoliated graphite electrode (EG electrode) in the electroanalysis of organic and inorganic water pollutants. This study also explored the applicability of this electrode in the removal of heavy metal pollutants in water. The EG material was successfully prepared by intercalating bisulphate ions into graphite flakes (>300 μm) followed by thermal shock at 800°C to obtain an exfoliated graphite. After compressing the EG at high pressure, the obtained circular sheets were used to fabricate electrodes. The electrochemical profiles of EG electrode and glassy carbon electrodes (GCE) were recorded and compared using cyclic voltammetryand square wave voltammetry in the presence of various supporting electrolytes and [Fe(CN)6]3-/4-, [Ru(NH3)6]2+/3+, ferrocene redox probes. In the supporting electrolytes (KCl, H2SO4, NaOH, tetrabutylammoniumtetraflouroborate, phosphate buffers), the potential windows of EG were found, in some cases, to be about 300 mV larger than that of GCE. The diffusion coefficients (cm2s-1) of the redox probes were calculated to be 3.638 x 10-6, 1.213 x 10-6 and 4.411 x 10-6 for [Fe(CN)6]3-/4-, [Ru(NH3)6]2+/3+ and ferrocene, respectively. These values are comparable to those obtained from GCE. Furthermore, EG was modified with various nanomaterials such as poly (propylene imine) dendrimer (PPI), gold nanoparticles, silver nanoparticles, dendrimer–gold nanoparticles composite, cobalt oxide and bismuth. The morphologies of the modified electrodes were studied using scanning electron microscopy and their electrochemical reactivities in the three redox probes were investigated. The current and the reversibility of redox probes were enhanced in the presence of modifiers in different degrees with dendrimer and gold nanoparticles having a favourable edge. The electrochemical determination of o-nitrophenol by square wave voltammetry using a nanocomposite of generation 2 poly(propyleneimine) dendrimer and gold nanoparticles modified GCEand EG electrode were compared. A characteristic reduction peak between -600 mV and -700 mV for o-nitrophenol was observed with enhanced current on both GCE and EG modified electrodes.

碩士
淡江大學
水資源及環境工程所
83
Organics from landfill leachate are complicated. After decomposition, inorganic salt and organic by-product might both be able to combine with Fe2+ to form chelate or to compete with.OH. That will affect the result of Fenton treatment. Hence, we conduct a study by using simple organics probing into several objectives separately during the process of Fenton treatment such as the impact of organic decomposition while existing the inorganic salt and the decomposing behavior of different organics by means of Fenton treatment. Furthermore, we focus study on landfill leach to explore the impact of inorganic salts to Fenton reaction. CO32- 、 Cl- 、 NO2- are three dominate players to the reaction process of Fenton treatment because they influence greatly to the decomposition of organic. We evaluate two fields by two methods of COD and TOC. In simple organic system, existing inorganic salt to the impact of organic through Fenton treatment as follows: by the evaluation of COD，then NO2->CO32->Cl-> NO3- ≒ SO42- by the evaluation of TOC, then CO32->Cl->NO2->SO42- NO3- In landfill leachate system as follows: by the evaluation of COD,then Cl->NO2->CO32->SO42-> NO3- by the evaluation of TOC,then CO32->NO2->Cl->SO42->NO3-

博士
國立中央大學
環境工程研究所
105
The current remediation technologies are not effective for the simultaneous removal of both organic and inorganic contaminants from the contaminated sites due to their different characteristics. In two decades ago, we had used a high molecular organic compound (HDTMA) to modify soil to enhance the SOM content, which increases the ability of organic compounds partitioning to the soil. One of the studies highlighted the preparation of adsorbents for both organic and inorganic pollutants by modifying sodium montmorillonite using different functionalized modifiers. The effects of different functional groups, including –SH，–S，–NH2，–COOH, of the modifier on the sorption are discussed. Since the long hydrocarbon chains, the water solubility of modifiers is restricted, the materials are prepared by cation exchanging with alkylammonium ions, and protonated of amine group in alkyl polyamine halide to increases water solubility. In addition, we were exploring the influence of different processing methods, via cation exchange and grafting, on the structure, physical and chemical characteristics and adsorption ability of modified montmorillonites. The adsorption behavior of the modified montmorillonites for both inorganic and organic pollutants was also discussed based on the structural and surface properties. The successful grafting of modifiers onto the interlayer was confirmed by spectral analysis. However, adsorption was mainly controlled not only by surface area but also by the nature and surface charge of the modifiers. Based on the experimental results, the soil modifier significant improved the sorption characteristics and, among two metal ions, Cu2+ showed enhanced adsorption. The uptake phenomenon was influenced by various combined factors such as the nature, surface charge and surface area of the modified soils. Due to small interlamellar spacing of the hydrophilic layered silicate surface of montmorillonite, the intercalated species are capable of increasing the interlayer spacing as pillars. According to the above principle, we present another method to modify soil using the specific modifier. The modified pillared soil could adsorb both the organic contaminants and the heavy metals simultaneously. The effect of different modifiers with different chain lengths on the d-spacing of montmorillonite was studied and discussed in detail. XRD experiments were carried out and it was found that the modifier with a longer carbon chain comparatively enhanced the interlamellar spacing than that of other modifiers. The influence of HCl, the amount of modifiers and temperature on the interlayer structure was also discussed. In addition, the alkyl chain on the soil surface can be regarded as a partition medium. Although, quaternary ammonium salt can effectively improve the organic matter content of the soil and recent researches on amine modified soil showed that under certain conditions, they can be used as dual adsorbents for the removal of both organic and inorganic pollutants, but the removal of nonionic organic compounds (NOCs) is not effective. Thus the final study was to propose a new concept to use clay composite materials in which polymers are intercalated into interlayer of clay. Such clay composite can possess positive and negative charges and thus can act as versatile adsorbents for both organic and inorganic pollutants (cation and anion). Finally, this study chooses a methyl methacylate (M), methacrylic acid (A) and dimethylaminoethyl methacrylate (D) to synthesize triblock polymers. The triblock copolymers successfully synthesized by RAFT polymerization method were confirmed by nuclear magnetic resonance (NMR) spectral analysis. In acidic conditions, the dimethylaminoethyl methacrylate is protonated (positively charged) which can be used for anionic pollutants, and in alkaline solution, methacrylic acid can possess negative charge which can adsorb inorganic heavy metal pollutants. Furthermore, methyl methacylate is considered to greatly enhance the distribution of NOCs in the hydrophobic environment. Not only sorption of different pollutants was carried out using these clay synthesized composite materials, but also the effect of pH and other parameters were studied. A systematic study was carried out in depth in order to understand the mechanism and various factors that can affect the adsorption phenomenon. Uptake of both organic (benzene; toluene; ethylbenzene; and xylene; in brief BTEX) and inorganic (Cu2+, Zn2+ and Cr2O7 2-) pollutants were explored and highlighted in the final study. The observed log Koc values for the distribution of organic pollutants onto clay are significantly high in this study. In all cases the adsorption of Cu2+ was comparatively larger than that of Zn2+. The affinity of modified clay for Cr2O72- is increased owing to the occurrence of pH value decreased. The obtained log Koc and log Kom values of BTEX in this study for modified montmorillonite are comparatively larger than those of unmodified montmorillonite or natural soil. The self-synthesized triblock copolymers were embedded in the pillared layered clays, that displayed enhanced adsorption of both organic and inorganic pollutants and hence it was concluded as a great potential candidate.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science. Johannesburg 2015
Exposure to inorganic and organic pollutants residues causes negative effects to human health. They can cause damage to the living organism as well as to the environment. Humans take up these pollutants through skin absorption, respiration and ingestion of contaminated food and also the drinking water as a potential contaminants exposure route for inorganic and organic pollutants to humans. Studies have shown that inorganic and organic pollutants can be retained in food crops at higher than the permissible levels, thus posing some health risks to consumers. This study sought to assess the potential risk posed by inorganic and organic pollutants to human health as a result of consuming raw food and processed food cooked in traditional utensils. The food samples and the traditional utensils were collected in Kinshasa and Johannesburg markets. In total ninety- two food samples were assessed. The food crops included: cabbage, cassava, beans, beef meat and fish (tilapia). Ten trace elements, namely: Al, As, Cd, Cr, Cu, Hg, Mn, Pb, Se and Zn were analysed in raw food samples using ICP-OES, ICP-MS and mercury analyser. These metals were also analysed in food cooked with the traditional utensils. The health risk indices calculated were: Daily Intake of Metal (DIM) and Hazard Index (HI). The results obtained reveal that the raw food collected in Johannesburg markets contained a significant (p ˂ 0.05) higher concentration in all elements than the food samples collected in Kinshasa markets. Hg was detected only in fish samples. It was observed that cooking utensils can leach some significant quantities of trace elements into food during processing, hence resulting increase the concentration of these metals in processed foods. The DIM exceeded the oral reference dose (Rfd) and the HI were ˃ 1 in all the food cooked. The results of metal found in this current investigation were above the standard permissible limit set by FAO/WHO. On the other hand, the levels of 17 organochlorine pesticides were assessed in uncooked and cooked beans, cabbage, cassava, fish and beef meat collected in Kinshasa and Johannesburg markets. It was noticed from the results recorder that the mean concentration of organochlorine pesticides in uncooked food collected in Johannesburg market were significantly high (p ˂ 0.05) than the uncooked food from Kinshasa markets. DDE recorded its highest mean level (253.58±4.78 μg kg-1) in beef meat samples collected in Johannesburg markets. The results from the current study revealed that after cooking the amounts of organochlorines were significantly reduce than the uncooked food. Residue amounts of organochlorine pesticides found in this study are considerably lower than the recommended amount of organochlorines set by WHO/FAO (300 μg kg-1).
MT2016

In this doctoral work, we have synthesized a series of GO based composite nanoadsorbents such as MgO-MgFe2O4 decorated GO (MgO-MgFe2O4/GO), amine functionalized GO mounted with ZnO-ZnFe2O4 (NH2-GO/ZnO-ZnFe2O4), AlOOH-FeOOH nanorods functionalized GO (GO/AlOOH-FeOOH) and GO/g-C3N4 decorated with Fe3O4 (GO/g-C3N4-Fe3O4) nanomaterials by using hydrothermal method. Then the prepared GO based metal oxide nanocomposites were used as novel adsorbent for adsorption study of inorganic pollutants such as fluoride ions (F-), hexavalent chromium (Cr(VI)), arsenate (As(V)) and organic pollutants like methylene blue (MB) dye, tetracycline (TC) antibiotic from water. The formation, composition, bonding, crystalline phase, surface morphology, size, and surface area of these prepared nanocomposites were analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, and BET analytical techniques. Batch adsorption experiments were carried out under various conditions including pH, time, concentration, adsorbent dose and temperature. The synthesized MgO-MgFe2O4/GO magnetic nanocomposite was used as adsorbent for removal of F- ions from water. The maximum adsorption capacity for F- ions removal is found to be 34 mg/g, which is higher as comparable to MgO-Fe2O3 nanocomposite. The amine functionalized GO decorated with ZnO-ZnFe2O4 (NH2-GO/ZnO-ZnFe2O4) nanocomposite material was used for remediation of Cr (VI) from water. It was observed that introduction of NH2 groups to GO/ZnO-ZnFe2O4 nanocomposite play a very important role for remediation of hexavalent chromium with a maximum uptake capacity of 109.89 mg/g. Apart from this we have also prepared GO/AlOOH-FeOOH composite nanomaterials by one step hydrothermal method and have used for decontamination of arsenate (As(V)) ions from water. Experimental finding reveals that the prepared GO based nanocomposite material is highly efficient for remediation of As(V) ions from water. Furthermore, we have also synthesized GO/g-C3N4 (graphitic carbon nitride) 2D layered composite materials decorated with Fe3O4 nanoparticles and have used for removal of methylene blue (MB) dye and tetracycline (TC) antibiotic from aqueous media. It was found that the adsorption of TC and MB was pH dependent and maximum adsorption capacities of 120 and 220 mg/g were achieved for TC and MB respectively. All the prepared GO based nanoadsorbents were regenerated and reused up to 5 successive cycles without major loss in their sorption capacity. From the obtained experimental results, plausible adsorption mechanism has been proposed for all adsorption process.

M.Sc.
This study was carried out to investigate the removal of organic and inorganic pollutants from water using phosphorylated and nonphosphorylated cyclodextrin polymers. The β-cyclodextrin was functionalized using various phosphorylating agents and the derivatives obtained were characterised with Fourier Transform-Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry. These derivatives were polymerized using hexamethylene diisocyanate (HMDI) as a cross-linking agent. The polymers were obtained in good yields ranging from 72 % to 93 %. They were characterised using Fourier Transform-Infrared (FT-IR), Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM)/EDXS), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) to confirm the presence of phosphorus groups after polymerization. The removal of cadmium (II), chromium (III), trichlorophenol (TCP) and pentachlorophenol (PCP) was investigated in batch-mode experiments under varying conditions of pH, initial concentration and contact time. The concentration of heavy metal ions in water was determined using inductively-coupled plasma-optical emission spectroscopy (ICP-OES) and that of organic pollutants was determined using ultraviolet-visible (UV-Vis) spectroscopy. The polymers were found to adsorb up to chromium (III) better than cadmium (II) at pH 6.5. The maximum percentage removal of chromium (III) ranged between 83.9 % and 95 % whilst that of cadmium (II) ranged from 24.5 % to 39 %. There was no significant difference in the adsorption capacity of phosphorylated and phosphorus-free polymers in the removal of metals. However, phosphorylation improved the efficiency of the polymers in the removal of chlorophenols. The maximum percentage removal of TCP ranged from 17 % to 80.1 % whilst that of PCP ranged from 23 % to 77.2 %. The results obtained in this study demonstrate that the polymers are promising materials for the removal of Cr (III), TCP and PCP from water.

D.Phil. (Chemistry)
This thesis describes the improvement of sorption capacity and efficiency of synthetic and biological adsorbents towards selected pollutants by introducing functional groups on the sorbents. Functionalization was achieved by chemically modifying the binding sites of the studied adsorbents. The sorbent materials considered were chemical resins (Amberlite XAD 1180) and biomass (maize tassels and seaweed). The adsorbents were modified with ethylenediamine in order to improve their capacity for extraction of heavy metals, namely lead, copper and cadmium from water. For the removal of phenols from water, maize tassels was modified with polydiallyldimethylammonium chloride (polyDADMAC). The main focus of the proposed study was to formulate cheap and sustainable ways of purifying contaminated water by exploiting the pollutants’ affinity towards the adsorbents. Parameters such as contact time, sorbent quantities, analyte concentrations, desorption solution (for stripping adsorbed metals for sorbent reuse) and pH were optimized. Different isotherms were applied on the experimental data to establish sorption mechanisms and energies involved during the sorption process. The Langmuir isotherm was used to test for monolayer sorption while the Freundlich model tested multilayer adsorption on heterogeneous surfaces...

The primary sources of water contamination are industrialization, urbanization, and agricultural activities, which are harmful to the environment and the living beings. The wastewater treatment is very necessary for saving the water to emancipate the living organisms. Among various treatment technologies, adsorption and biodegradation are the most efficient methods for removing various pollutants from wastewater. The integration of adsorption and biodegradation processes for the treatment of organic compounds leads to the enhancement of the degradation rate and adsorption capacity. Among various adsorbents used, the activated carbon is one of the most efficient adsorbents due to high surface area and developed pore structures, and a actual support media for microbial growth. In this study, the Fox nutshell has been used as a novel precursor material for the preparation of activated carbons. These are the residue with no commercial value. The Fox nutshell contains low ash (5%) content and high volatile matter (70.1%) that is favorable for activated carbon preparation. Therefore, the Fox nutshell has been a worthwhile material for the preparation of the activated carbon. The activated carbons were prepared by chemical activation method using zinc chloride, orthophosphoric acid, and potassium carbonate. The effect of various process parameters such as heating rate, activation time, carbonization temperature and impregnation ratio on porous characteristics of the prepared activated carbons has been investigated. The proximate and ultimate analyses of the prepared activated carbons was carried out by using standard methods and CHNS analyzer, respectively. The prepared activated carbons were characterized by using N2 adsorption-desorption isotherm at 77 K. The surface functional groups present on the prepared ACs surface were determined by the Fourier Transform Infrared Spectroscopy (FTIR) analysis. The Field Emission Scanning Electron Microscope (FESEM) analysis revealed the surface texture of the ACs while Transmission Electron Microscopy (TEM) analysis is used to visualize the presence of micropores network. The prepared activated carbon with a ZnCl2 activator (ACZC-600-2.0) which has the highest BET surface area of 2869 m2/g and pore volume of 1.96 cm3/g is obtained at the following conditions: 600 ºC carbonization temperature, 2 impregnation ratio and one hr activation time. The prepared activated carbon with an H3PO4 activating agent (ACPA-700-1.5) has the BET surface area of 2636 m2/g and pore volume of 1.53 cm3/g is obtained at 700 ºC carbonization temperature, 1.5 impregnation ratio and one hr activation time. The another prepared activated carbon with a K2CO3 activator (ACKC-800-0.5) has the BET surface area of 1236 m2/g and pore volume of 0.98 cm3/g which has the highest surface area and pore volume is obtained at 800 ºC carbonization temperature, 0.5 impregnation ratio and activation time of one hr. Batch adsorption experiments of phenol, methylene blue (MB) and Cr(VI) onto prepared activated carbons were carried out at various initial concentration. Adsorption kinetics of phenol, MB and Cr(VI) were studied by using different kinetic models, i.e., the pseudo-first-order model, the pseudo-second-order model, and the intraparticle diffusion model. The experimental adsorption isotherms of these adsorbates on the prepared activated carbons were analyzed using the Langmuir, Freundlich, and Temkin isotherm models. adsorption capacity (qe) of 500 mg/L of initial phenol concentration onto ACZC-600-2.0 and ACPA-700-1.5 are 75.37 and 83.21 mg/g, respectively. The equilibrium adsorption capacity (qe) of MB onto ACZC-600-2.0 and ACPA-700-1.5 are 968.74 and 766.53 mg/g, respectively for 500 mg/L of initial concentration. Adsorption capacity (qe) of 10 mg/L of initial Cr(VI) concentration onto ACZC-600-2.0 and ACPA-700-1.5 are 43.45 and 56.31 mg/g, respectively. The potential applications of the prepared activated carbons for removal of adsorbates have been studied in fixed bed column. The effects of the bed height and flow rate of phenol, MB and Cr(VI) adsorption onto prepared activated carbons were also studied. The bacterial strain of Pseudomonas putida (MTCC 1194) has been taken for the phenol biodegradation in both suspended and immobilized phase. The bacterial strain has been acclimatized up to 1000 mg/L of phenol concentration. Biological granular activated carbon (BGAC) shows more efficiency than the free cells for phenol removal due to both adsorption and biodegradation process. The BGAC has been used in fluidized bed bioreactor for treatment of synthetic phenol wastewater. In fluidized bed bioreactor, effects of inlet flow rate of the wastewater, different phenol concentration solutions, and the ratio of bed (settled) volume to bioreactor volume (Vb/VR) on the removal of phenol were studied.

A wide range of emerging pollutants, such as pharmaceuticals and pesticides, has been detected in water sources, due to the ineffectiveness of conventional wastewater treatment technologies to remove efficiently these compounds. This is a matter of great concern due to potential harmful effects on the environment and human health. In this context, the search for eco-friendly and low-cost efficient sorbents have prompted recent developments for biopolymer-based materials and their use in water decontamination. In particular, polysaccharide-based nanocomposites are very attractive as nanosorbents owing to functional groups that provide affinity towards a wide diversity of pollutants. In order to act as efficient nanosorbents, the biopolymers should be easily separated from treated solutions. From a materials chemistry perspective, this may be achieved by grafting the biopolymers to inorganic water-insoluble supports, in the form of organic-inorganic hybrid materials. Due to economic and environmental factors, the concept of recoverable and reusable sorbents has gained importance, and subsequently, the use of magnetic sorbents, namely magnetic nanoparticles, has raised increasing interest. Magnetic nanomaterials are very convenient for removing pollutants because they combine large specific surface area that favors adsorption and magnetic features that allow easy and fast separation from water. The surface modification with biopolymers enhances the adsorptive capabilities of magnetic nanoparticles without compromising the low-cost. However, in order to attain high adsorptive performance, a rational design of the surface of the nanoparticles is essential. Furthermore, the nanosorbents should exhibit high adsorption capacity and reusability. To tackle this challenge, this thesis explores magnetic biopolymer-hybrid based nanomaterials. Core-shell composite nanoparticles comprising a core of magnetite (~50 nm), uniformly coated by a shell of biopolymer-siliceous material were prepared using a one-step sol-gel based procedure. The applicability of the approach was demonstrated by invoking distinct chemical nature and ionic character of biopolymers, namely cationic (chitosan and quaternary derivatives) and anionic (ƙ-, ι-, λ-carrageenan and alginic acid) polysaccharides, and a natural protein (gelatin). The adsorptive performance of the particles towards a number of emerging pollutants, namely pharmaceuticals (diclofenac, naproxen, ketoprofen, sulfamethoxazole, ciprofloxacin and tetracycline) and pesticides (glyphosate) frequently detected in waters was investigated under several operational conditions. Overall, these magnetic nanosorbents showed high adsorption capacity and reusability, as originally intended. Although further research on complex real waters is still required, the results indicate that these biopolymer-based magnetic nanosorbents are among the most effective magnetic systems reported so far, to remove tested pollutants from water.
Uma vasta gama de poluentes emergentes, como fármacos e pesticidas, tem sido detetada em fontes de água, devido à ineficácia das tecnologias convencionais de tratamento de águas residuais em remover completamente estes compostos. Este facto é um motivo de grande preocupação devido aos potenciais efeitos nocivos para o meio ambiente e para a saúde humana. Nesse contexto, a procura por adsorventes amigos do ambiente, eficientes e de baixo custo levou a recentes desenvolvimentos de materiais à base de biopolímeros e a sua aplicação na descontaminação da água. Em particular, os nanocompósitos à base de polissacarídeos são materiais muito atrativos como nanoadsorventes por conterem grupos funcionais que fornecem afinidade para uma diversidade de poluentes. De forma a atuarem como nanoadsorventes eficientes, os biopolímeros devem ser facilmente separados das soluções tratadas. Do ponto de vista da química dos materiais, este objetivo pode ser alcançado através da ligação dos biopolímeros a suportes inorgânicos insolúveis em água, na forma de materiais híbridos orgânicos-inorgânicos. Devido a fatores económicos e ambientais, o conceito de adsorventes recuperáveis e reutilizáveis tem ganho importância e, consequentemente, o uso de adsorventes magnéticos, nomeadamente nanopartículas magnéticas, tem despertado um crescente interesse. Os nanomateriais magnéticos são convenientes para a remoção de poluentes, pois possuem uma elevada área superficial específica que favorece a adsorção, e propriedades magnéticas que permitem uma fácil e rápida separação da água. A modificação da superfície das nanopartículas magnéticas com biopolímeros aumenta a sua capacidade de adsorção sem comprometer o baixo custo do material. No entanto, para se obter um elevado desempenho de adsorção, é essencial um desenho racional da superfície das nanopartículas. Além disso, os nanoadsorventes devem exibir elevada capacidade de adsorção e reutilização. Para enfrentar este desafio, esta tese explora nanomateriais híbridos magnéticos à base de biopolímeros. Assim, foram preparadas nanopartículas do tipo núcleo-coroa compostas por um núcleo de magnetite (~ 50 nm) uniformemente revestido por uma capa de biopolímero-sílica através de um procedimento sol-gel de uma etapa. A aplicabilidade da abordagem foi demonstrada com base em biopolímeros de diferente natureza química e caráter iónico, como polissacarídeos catiónicos (quitosano e derivados quaternários), aniónicos (ƙ-, ι-, λ-carragenano e ácido algínico) e proteínas naturais (gelatina). O desempenho das partículas na adsorção de uma série de poluentes emergentes, nomeadamente fármacos (diclofenac, naproxeno, cetoprofeno, sulfametoxazol, ciprofloxacina e tetracicilina) e pesticidas (glifosato) frequentemente detetados na água foi investigado em diversas condições operacionais. Em geral, estes nanoadsorventes magnéticos apresentam elevada capacidade de adsorção e reutilização, conforme pretendido originalmente. Embora sejam necessários mais estudos em águas reais complexas, os resultados indicam que estes nanoadsorventes magnéticos à base de biopolímeros estão entre os sistemas magnéticos mais eficazes para a remoção da água dos poluentes testados.
Programa Doutoral em Nanociências e Nanotecnologia

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology
Water pollution caused by organic and inorganic contaminants represents an important ecological and health hazard. Simultaneous treatment of organic and inorganic contaminants had gradually gained great scientific interest. Advanced oxidation processes such as photocatalysis, using TiO2 as a photocatalyst, have been shown to be very robust in the removal of biorecalcitrant pollutants. These methods offer the advantage of removing the pollutants, in contrast to conventional techniques. At present, the main technical challenge that hinder its commercialization remained on the post-recovery of the photocatalyst particles after water treatment. Supporting of the photocatalyst on the adsorbent surface is important as it assists during the filtration step, reducing losses of the materials and yielding better results in degrading pollutants. To overcome this challenge, in this study composite photocatalysts of TiO2/zeolite and TiO2/silica were prepared and investigated to explore the possible application in the simultaneous removal of organic and inorganic compounds from contaminated water. The main objective of this study was to investigate the heterogeneous photocatalytic degradation of organic compounds in the presence of metal ions using composite photocatalysts. The Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX), Raman spectroscopy (RS) and zeta potential (ZP) analyses were used to characterize the prepared composite photocatalysts. The successive composite photocatalysts were used in a semi-batch reactor under an irradiation intensity of 5.5 mW/m2 (protected by a quartz sleeve) at 25 ± 3°C for the photocatalytic degradation of synthetic textile (methyl orange) and agricultural (atrazine) wastewater in the presence of ions. The effect of operating parameters such as TiO2 composition on supporting material, particle size, composite photocatalyst loading, initial pollutant concentration and pH were optimized. The effects of inorganic salts and humic acid on dye and pesticides degradation were also studied, respectively. The performance of the photocatalyst reactor was evaluated on the basis of color removal, metal ion reduction, total organic carbon (TOC) reduction, intermediates product analysis and modeling of kinetics and isotherms. Different kinetic and isotherm models were introduced and applied in this work. Important aspects such as error functions with the optimal magnitude were used for the selection of the best suitable model.
European Union. City of Mikkeli, Finland. Water Research Commission (RSA)

abstract: Electrospinning is a means of fabricating micron-scale diameter fiber networks with enmeshed nanomaterials. Polymeric nanocomposites for water treatment require the manipulation of fiber morphology to expose nanomaterial surface area while anchoring the nanomaterials and maintaining fiber integrity; that is the overarching goal of this dissertation. The first investigation studied the effect of metal oxide nanomaterial loadings on electrospinning process parameters such as critical voltage, viscosity, fiber diameter, and nanomaterial distribution. Increases in nanomaterial loading below 5% (w/v) were not found to affect critical voltage or fiber diameter. Nanomaterial dispersion was conserved throughout the process. Arsenic adsorption tests determined that the fibers were non-porous. Next, the morphologies of fibers made with carbonaceous materials and the effect of final fiber assembly on adsorption kinetics of a model organic contaminant (phenanthrene, PNT) was investigated. Superfine powdered activated carbon (SPAC), C60 fullerenes, multi-walled carbon nanotubes, and graphene platelets were added to PS and electrospun. SPAC maintained its internal pore structure and created porous fibers which had 30% greater PNT sorption than PS alone and a sevenfold increase in surface area. Carbon-based nanomaterial-PS fibers were thicker but less capacious than neat polystyrene electrospun fibers. The surface areas of the carbonaceous nanomaterial-polystyrene composites decreased compared to neat PS, and PNT adsorption experiments yielded decreased capacity for two out of three carbonaceous nanomaterials. Finally, the morphology and arsenic adsorption capacity of a porous TiO2-PS porous fiber was investigated. Porous fiber was made using polyvinylpyrrolidone (PVP) as a porogen. PVP, PS, and TiO2 were co-spun and the PVP was subsequently eliminated, leaving behind a porous fiber morphology which increased the surface area of the fiber sevenfold and exposed the nanoscale TiO2 enmeshed inside the PS. TiO2-PS fibers had comparable arsenic adsorption performance to non-embedded TiO2 despite containing less TiO2 mass. The use of a sacrificial polymer as a porogen facilitates the creation of a fiber morphology which provides access points between the target pollutant in an aqueous matrix and the sorptive nanomaterials enmeshed inside the fiber while anchoring the nanomaterials, thus preventing release.
Dissertation/Thesis
Doctoral Dissertation Engineering 2018

The distribution and potential sources of 15 polycyclic aromatic hydrocarbons (PAHs) in soils and Digitaria eriantha in the vicinity of three South African coal-fired power plants, Matla, Lethabo and Rooiwal were determined by gas chromatography–mass spectrometry. An ultrasonic assisted dispersive liquid-liquid microextraction (UA-DLLME) method was developed for the extraction of polycyclic aromatic hydrocarbon in soil, followed by determination using gas chromatography mass spectrometry. The study showed that an extraction protocol based on acetonitrile as dispersive solvent and C2H2Cl2 as extracting solvent, gave extraction efficiencies comparable to conventional soxhlet extraction for soil samples. The extraction time using ultrasonication and the volume of the extraction solvent was also investigated. Using a certified reference material soil (CRM), the extraction efficiency of UA-DLLME ranged from 64 to 86% in comparison with the Soxhlet result of 73 to 95%. In comparison with the real sample, the CRM result did not show a significant difference at 95% C.I. The UA-DLLME proved to be a convenient, rapid, cost-effective and greener sample preparation approach for the determination of PAHs in soil samples. PAH compound ratios such as phenanthrene/phenanthrene + anthracene (Phen/ Phen + Anth) were used to provide a reliable estimation of emission sources. The total PAH concentration in the soils around three power plants ranged from 9.73 to 61.24 μg g−1, a range above the Agency for Toxic Substances and Disease Registry levels of 1.0 μg g−1 for a significantly contaminated site. Calculated values of the Phen/Phen + Anth ratio were 0.48±0.08, 0.44±0.05, and 0.38+0.04 for Matla, Lethabo and Rooiwal, respectively. The flouranthene/fluoranthene + pyrene (Flan/ Flan + Pyr) levels were found to be 0.49±0.03 for Matla, 0.44±0.05 for Lethabo, and 0.53±0.08 for Rooiwal. Such values indicate a xx pyrolytic source of PAHs. Higher molecular weight PAHs (five to six rings) were predominant, suggesting coal combustion sources. The carcinogenic potency B[a]P equivalent concentration (B[a] Peq) at the three power plants ranged from 3.61 to 25.25, indicating a high carcinogenic burden. The highest (B[a] Peq) was found in samples collected around Matla power station. It can, therefore, be concluded that the soils were contaminated with PAHs originating from coal-fired power stations. Nine metals (Fe, Cu, Mn, Ni, Cd, Pb, Hg, Cr and Zn) were analysed in soil and the Digitaria eriantha plant around three coal power plants (Matla, Lethabo and Rooiwal), using ICP-OES and GFAAS. The total metal concentration in soil ranged from 0.05 ± 0.02 to 1835.70 ± 70 μg g-1, 0.08 ± 0.05 to 1743.90 ± 29 μg g-1 and 0.07 ± 0.04 to 1735.20 ± 91 μg g-1 at Matla, Lethabo and Rooiwal respectively. The total metal concentration in the plant (Digitaria eriantha) ranged from 0.005 ± 0.003 to 534.87 ± 43 μg g-1 at Matla, 0.002 ± 0.001 to 400.49 ± 269 μg g-1 at Lethabo and 0.002 ± 0.001 to 426.91 ± 201 μg g-1 at Rooiwal. The accumulation factor (A) of less than 1 (i.e. 0.003 to 0.37) at power plants indicates a low transfer of metal from soil to plant (excluder). The enrichment factor values obtained (2.4 – 5) indicate that the soils are moderately enriched, with the exception of Pb that had significant enrichment of 20. The Geo-accumulation Index values of metals indicate that the soils are moderately polluted (0.005 – 0.65), except for Pb that showed moderate to strong pollution (1.74 – 2.53).
Chemistry
D. Phil. (Chemistry)