Academic literature on the topic 'Silica sand media'

ABSTRACT Carbon Monoxide (CO) produced from smoke by cigarettes has a certain level that accumulates indoors and affects indoor air quality. The purpose of this study was to see how effective the method of air stripping in reducing CO gas concentration by using activated carbon, silica sand, and zeolite media in the experimental room which has a volume of 1000 litters. This research was performed in the laboratory by using pre-experiment random group design. The independent variables of this study include activated carbon, zeolite, and silica sand as adsorbent, while the dependent variable of this study was carbon monoxide concentration. The test was carried out by measuring the accumulation of CO gas from burning cigarette, and subsequent testing with air stripping test treatment by using the varies adsorbent on 30 minutes. From the test results obtained the highest percentage reduction of CO concentration, which was 50.89% by using the activated carbon adsorbent medium, and the lowest percentage of CO reduction was 5.85% by using silica sand adsorbent medium. The difference of CO gas concentration was significant after passing air stripping process by using zeolite media, activated carbon and silica sand with significance level p value = 0.0001. There were significant differences in the ability of zeolite, activated carbon and silica sand to reduce CO concentration, with p value = 0.0001. Keywords: Carbon Monoxide Concentration, Air Stripping, Adsorption, Activated Carbon, Zeolite, Silica Sand ABSTRAK Karbon Monoksida (CO) yang dihasilkan dari asap oleh rokok memiliki kadar tertentu yang terakumulasi di dalam ruangan dan mempengaruhi kualitas udara dalam ruangan. Tujuan dari penelitian ini adalah untuk melihat seberapa besar efektivitas metode air stripping dalam menurunkan konsentrasi gas CO dengan menggunakan media karbon aktif, pasir silika dan pasir zeolit di dalam ruangan percobaan yang memiliki volume 1000 liter. Penelitian ini merupakan penelitian yang dilakukan di dalam laboratorium dengan menggunakan pre-eksperimen desain kelompok acak. Variabel bebas dari penelitian ini meliputi karbon aktif, pasir zeolite dan pasir silika sebagai adsorben, sedangkan variabel terikat dari penelitian ini konsentrasi karbon monoksida.. Pengujian dilakukan dengan mengukur akumulasi gas CO dari pembakaran rokok, dan pengujian berikutnya dengan perlakuan uji air stripping menggunakan adsorben yang berbeda-beda dengan waktu pengujian selama 30 menit. Dari hasil uji didapatkan persentase penurunan konsentrasi CO tertinggi, yaitu 50,89 % dengan menggunakan media adsorben karbon aktif, dan persentase penurunan CO terendah yaitu 5,85% dengan menggunakan media adsorben pasir silika. Perbedaan konsentrasi gas CO yang signifikan setelah melalui proses air stripping dengan menggunakan media zeolit, karbon aktif dan pasir silika dengan taraf signifikasi nilai p = 0,0001. Ada perbedaan nilai yang signifikan terhadap kemampuan media zeolit, karbon aktif dan pasir silika dalam menurunkan konsentrasi CO, dengan nilai p = 0,0001. Kata kunci : Konsentrasi Karbon Monoksida, Air Stripping, Adsorbsi, Karbon aktif, Zeolit, pasir silika

<p><strong>ABSTRACT</strong></p><p>This study aims to determine the most effective type of living filter media for the bacteria Nitrosomonas sp. in order to improve water quality in aquaponics systems. The method used in this study was completely randomized design, consisting of five treatments and each was repeated three times. The treatments were: A (without addition of filter media), B (addition of palm fibers, silica sand, and activated carbon), C (addition of palm fibers, silica sand, gravel, and activated carbon), D (addition of palm fibers, silica sand, rocks, and activated carbon), and E (addition of palm fibers, silica sand, bioball, and activated carbon). Parameters measured were: 1) the number of Nitrosomonas bacteria, 2) water quality (ammonia, nitrate, and phosphate); and, 3) productivity of fish and Chinese spinach. Data were analyzed using a descriptive method. The findings show that the highest number of bacteria was found in treatment E, 9.29×105 CFU/mL on the bioball filter media and 4.43×105 CFU/mL in rearing tanks. The best water quality was in treatment B, with a concentration of ammonia of 0.17 mg/L, nitrate of 0.33 mg/L, and phosphate of 0.54 mg/L. Plant productivity was the best in treatment B in which the average length and weight reach 48.1 cm and 11.1 grams of plant/week, respectively. The best fish growth was seen in treatment C with an absolute growth rate of 4.4 grams and a specific growth rate of 1.9%/day. The recommended filter was made of Arenga pinnata fibers, silica sand, gravels, and active carbon of about 2 cm thick each.The results showed that the type of filter on the aquaponic system had an effect on the amount of Nitrosomonas sp. in water, water quality, and the productivity of Chinese spinach.</p><p>Keywords: aquaponics, filter, water quality, Nitrosomonas sp.</p><p><strong>ABSTRAK</strong></p><p>Penelitian ini bertujuan untuk menentukan jenis filter yang paling efektif sebagai media hidup bakteri Nitrosomonas sp. sehingga menghasilkan kualitas air yang baik dalam sistem akuaponik. Rancangan percobaan yang digunakan adalah rancangan acak lengkap, yaitu lima perlakuan dengan tiga kali pengulangan. Perlakuan dalam penelitian ini meliputi: A (tanpa penambahan media filter), B (penambahan media filter ijuk, pasir silika, dan karbon aktif), C (penambahan media filter ijuk, pasir silika, kerikil, dan karbon aktif), D (penambahan media filter ijuk, pasir silika, batu, dan karbon aktif), dan E (penambahan media filter ijuk, pasir silika, bioball, dan karbon aktif). Parameter yang diamati adalah: 1) jumlah bakteri, 2) kualitas air (meliputi amonia, nitrat, dan fosfat), serta 3) produktivitas ikan dan kangkung air. Data hasil penelitian dianalisis secara deskriptif. Hasil penelitian menunjukkan bahwa jumlah kelimpahan bakteri Nitrosomonas sp. tertinggi terdapat pada perlakuan E, yaitu 9,29×105 CFU/mL pada media filter bioball dan 4,43×105 CFU/mL pada media air pemeliharan. Adapun kualitas air terbaik yaitu pada perlakuan B dengan konsentrasi amonia 0,17 mg/L, nitrat 0,33 mg/L, dan fosfat 0,54 mg/L. Produktivitas kangkung terbaik yaitu pada perlakuan B dengan panjang rata-rata mencapai 48,1 cm dan bobot tanaman 11,1 gram/minggu. Pertumbuhan ikan terbaik terdapat pada perlakuan C, dengan nilai pertumbuhan ikan mutlak sebesar 4,4 gram dan pertumbuhan spesifik 1,9%/hari. Hasil penelitian menunjukkan bahwa jenis filter pada sistem akuaponik berpengaruh terhadap jumlah Nitrosomonas sp. dalam air, kualitas air, dan produktivitas tanaman kangkung. Filter yang disarankan dari hasil penelitian ini adalah yang tersusun atas ijuk, pasir silika, batukerikil, dan karbon aktif masing-masing setinggi ±2 cm.</p><p>Kata kunci: akuaponik, filter, kualitas air, Nitrosomonas sp., produktivitas tanaman</p>

Cultures <i>in vitro</i> made in agar are rather precarious, because gel strength varies both with the medium formula used and the source and grade of agar. Any solidifying agent (like for example agar) should be strong enough to support cultivated plantlets, yet liquid enough to allow the nutrients and drossy products from plants through the medium. It should also be a chemically inert material. Agar, especially in acid solutions, is an undefined constituent of culture media, namely in the mentioned properties. Silica sand, used in cultures of herbs up to the present time, is applicable also in cultures of <i>Sorbus sudetica</i>. The required acid medium is exactly defined if sand is substituted for agar. Similar cultures of wood species, including conifers, will be realized in future research.

Tanaman air adalah bagian penting dari ekosistem air tawar. Salah satu spesies yang terkenal adalah Bacopa australis. Hobiis aquascape saat ini memiliki ketertarikan tinggi terhadap tanaman air dengan kualitas yang bagus dari setiap spesiesnya. Metode perbanyakan tanaman air tanpa tanah, lahan pertanian dan air perlu dilakukan untuk memenuhi keinginan tersebut. Tujuan dari penelitian ini adalah untuk mendapatkan formula media kultur jaringan dan zat pengatur tumbuh yang tepat untuk multiplikasi dalam perakitan mother plant (tanaman induk) Bacopa australis, serta mendapatkan media terbaik untuk aklimatisasi. Media yang digunakan adalah media Murashige dan Skoog (MS) A padat dengan perbedaan konsentrasi zat pengatur tumbuh. Perlakuan uji dalam kombinasi zat pengatur tumbuh (a) 0,50 mg/L BAP + 0,50 mg/L kinetin; (b) 0,50 mg/L BAP; dan (c) 0,50 mg/L 2,4-D. Aklimatisasi tanaman induk dilakukan pada berbagai media antara lain 1) pasir silika + pupuk aqua soil amazonia, 2). pasir malang + pupuk aqua soil amazonia, 3) pasir silika + pupuk cair; 4) pasir malang + pupuk. Hasil yang diperoleh, yaitu formula media kultur terbaik untuk multiplikasi tunas tanaman B. australis secara in-vitro adalah media MS (A) yang diperkaya dengan 0,5 mg/L BAP + 0,5 mg/L kinetin, sedangkan aklimatisasi terbaik pada media pasir malang + pupuk aqua soil amazonia.Water plant is an important part of freshwater ecosystems. One of the famous species is Bacopa australis. Today, many aquascape hobbyists have a high interest in aquatic plant species that have good aesthetic appearances. To answer this challenge, a new method in-vitro propagation of aquatic plants, planted without soil, agricultural land and water was conducted. The aim of this research was to find the best growth regulator hormon formula and aclimatisation medium, in creating the mother plant Bacopa australis. The medium used was MS (Murashige and Skoog, 1974) with different growth regulator hormon, i.e: (a) 0.50 mg L-1 BAP + 0.50 mg L-1 kinetin, (b) 0.50 mg L-1 BAP, (c) 0.50 mg L-1 2.4-D. The aclimatisation of the mother plant candidates used four treatments, i.e: (1) silica sand + aqua soil amazonia fertilizer, (2) malang sand + aqua soil amazonia fertilizer, (3) silica sand + liquid fertilizer, (4) malang sand + liquid fertilizer. The results showed that the best formula for in-vitro multiplication mother plant of Bacopa australis was MS medium with 0.5 mg/L BAP + 0.5 mg/L kinetin (treatment A). The best medium aclimatisation was malang sand + aqua soil amazonia fertilizer medium.

The increase in vehicle washing services has a major impact on the environment, human health and ecosystems in water bodies. One method of treating vehicle washing liquid waste using a filtration system has been proven to be effective and capable of breaking down pollutants contained in wastewater. However, filtration using activated carbon, silica sand, zeolite and gravel media with different variations and doses of media thickness to reduce levels in the parameters pH, TSS, COD and Phosphate has not been studied. This study was conducted to determine the effect of variations and doses of filter media and their effectiveness in reducing the levels of TSS, COD, pH and Phosphate in vehicle washing waste, with variations in the thickness of activated carbon media 10, 20, 25 cm and silica sand, zeolite, gravel 15 , 20 cm. The results showed that activated carbon, silica sand, zeolite and gravel media were able to reduce TSS, COD, pH and phosphate levels. The decrease in levels is highest in the 6th variation. The percentage of TSS is 97.13%, COD is 93.93%, Phosphate is 74% and a decrease in pH 7. From the data presented, it can be seen that all variations are able to reduce levels of pollutant parameters. in vehicle washing waste.

Arbuscular mycorrhizae form obligate symbioses with the majority of vascular plants Propagation of these fungi relies on maintenance of pure pot cultures typically sterile sand supplemented with a nutrient solution is used However river sand is inappropriate for New Zealand species as it is denser than soils and prone to water logging Three different media (silica sand pumice and potting mix) at two particle sizes (5001000 micro;m and 10001400 micro;m) were mixed in nine combinations for the propagation of arbuscular mycorrhizae spores The results showed that the silica sand/pumice medium (5001000 micro;m bulk density of 1) produced the greatest (Plt;001) number of spores (170/ml of substrate) The density of the media had the greatest effect on spore formation Inoculations of grapevines with spores derived from these cultures significantly improved both root and shoot growth

The effect of hydraulic loading rate (HLR) and media type on the removal of bulk organic matter and nitrogen from primary effluent during soil aquifer treatment was investigated by conducting laboratory-scale soil column studies. Two soil columns packed with silica sand were operated at HLRs of 0.625 and 1.25 m/d, while a third column was packed with dune filtering material and operated at HLR of 1.25 m/d. Bulk organic matter was effectively removed by 47.5 ± 1.2% and 45.1 ± 1.2% in silica sand columns operated at 0.625 and 1.25 m/d, respectively and 57.3 ± 7.6% in dune filtering material column operated at 1.25 m/d. Ammonium-nitrogen reduction of 74.5 ± 18.0% was achieved at 0.625 m/d compared to 39.1 ± 4.3% at 1.25 m/d in silica sand columns, whereas 49.2 ± 5.2% ammonium-nitrogen reduction was attained at 1.25 m/d in the dune filtering material column. Ammonium-nitrogen reduction in the first 3 m was assumed to be dominated by nitrification process evidenced by corresponding increase in nitrate. Part of the ammonium-nitrogen was adsorbed onto the media, which was observed at higher rates between 3 and 5 m in silica sand column operated at HLR of 0.625 m/d and dune filtering material column operated at 1.25 m/d compared to 1.25 m/d silica.

Recent research has shown discrepancies between the prevailing mathematical representations of near-surface shear strength and the observed shear strengths. This investigation focuses on three granular materials, i.e., 1) poorly-graded, medium-fine silica-quartz sand, 2) an engineered silica-quartz mix of 3.38-mm and 0.638-mm sub-angular particles, and 3) an angular fused quartz sand. Specimens were tested under load-controlled conditions at variable saturations in order to identify and quantify the influence of suction on the granular structures and failure modes. All three materials exhibited localized radial particle force chain buckling failures in unconfined drained dry (UDκ) conditions and classical shear failures in the unconfined drained unsaturated shear (UDP) conditions. In unconfined drained suction failures (UDS) conditions, the poorly-graded, medium-fine silica-quartz sand exhibited a bulging and sloughing failure without weeping, while the other two materials wept and then held loads before failure. Thus, it is suggested that the pore fluid had a predominate lubrication (strength weakening) effect, and the assumption of structure stiffening (strength increase) from matric suction may not be valid at near-surface conditions for sub-angular silica-quartz materials but is valid for the angular fused quartz.

Abstract In our research we pre-treated synthetically produced greywaters with filtration on various filters. We characterised the quality of greywater samples using several parameters. We investigated these parameters on the untreated and pre-treated samples as well. We evaluated the efficiency of the treatments by measuring the characteristic parameters. It was shown that the most effective pre-treatment for the greywater’s preparation for reuse is filtration on silica sand or activated charcoal and silica sand combined filter media.

The growing use of nanoscale zero-valent iron (NZVI) in the remediation of contaminated groundwater raises concerns regarding its transport in aquifers. Laboratory-scale sand-packed column experiments were conducted with bare and sucrose-modified NZVI (SM-NZVI) to improve our understanding of the transport of the nanoparticles in saturated porous media, as well as the role of media size, suspension injection rate and concentration on the nanoparticle behavior. As the main indicative parameters, the normalized effluent concentration was measured and the deposition rate coefficient (k) was calculated for different simulated conditions. Overall, compared to the high retention of bare NZVI in the saturated silica column, SM-NZVI suspension could travel through the coarse sand column easily. However, the transport of SM-NZVI particles was not very satisfactory in a smaller size granular matrix especially in fine silica sand. Furthermore, the value of k regularly decreased with the increasing injection rate of suspension but increased with suspension concentration, which could reflect the role of these factors in the SM-NZVI travel process. The calculation of k-value at the tests condition adequately described the experimental results from the point of deposition dynamics, which meant the assumption of first-order deposition kinetics for the transport of NZVI particles was reasonable and feasible.

Two-phase flow in porous media is an important subsurface process that has significant impacts on the global economy and environments. To study two-phase system in porous media, capillary pressure (Pc ), relative permeability (Kr), bulk electrical conductivity (σb) and bulk relative permittivity (εb) are often employed as characterization parameters. Interestingly, all of these parameters are functions of water saturation (S). However, the non-uniqueness in the Pc -S, Kr-S,σb-S and εb-S relationships pose considerable challenges in employing them for effective monitoring and control of the two-phase flow processes. In this work, laboratory scale experiments and numerical simulations were conducted to investigate the factors and conditions contributing to the non-uniqueness in the above relationships for silicone oil-water and supercritical CO2-water flow in porous media, with a special emphasis on geological carbon sequestration. Specifically, the dynamic capillary pressure effect, which indicates the dependence of the Pc - S relationship on the rate of change of saturation (αS/αt) during two-phase flow in porous media was investigated. Using a silicone oil-water system, the dynamic capillary pressure effect was quantified in term of the parameter named the dynamic coefficient, τ , and it was found to be dependent on the domain scale and the viscosity ratio of the two fluids. It was found that τ increases with the domain scale and the viscosity ratio. It is inversely affected by αS αt , which is related to the degree of resistance to the fluid motion, namely, viscosity. In almost all cases, τ was found to decrease monotonically with an increase in water saturation, S. An order increase in magnitude of τ was observed as the domain scale increases from 4cm scale to 8cm in height. A similar order of increase in τ was observed in the 12cm high domain scale. There is an order increase in the value of τ for the silicone oilwater system as the viscosity ratio increases from 200 to 500. For the supercritical CO2 (scCO2) and water system in porous media, the experiments and numerical simulations showed that τ increases with rising system temperature and decreasing porous media permeability. Dimensionless analysis of the silicone oil-water experimental results showed that by constructing non-dimensional groups of quantities expressing a relationship among different variables on which τ depends, it is possible to summarise the experimental results and determine their functional relationship. A generalised scaling relationship for τ was derived from the dimensionless analysis which was then validated against independent literature data. The exercise showed that the τ-S relationship obtained from the literature and the ii scaling relationship match reasonably well. This work also demonstrated the applicability of an artificial neural network (ANN) as an alternative computational platform for the prediction of the domain scale dependence of τ . The dependence of the Kr-S relationship on αS/αt was also investigated. The results showed that the Kr-S curve under dynamic flow condition is different from that under the quasi-static condition. Kr for water (Krw) increases with increasing water saturation and decreases with the increase in viscosity ratio while Kr for silicone oil (Krnw) increases with decreasing water saturation as well as with the increase in viscosity ratio. Also, Krw decreases while Krnw increases with the increasing boundary pressure. However, the εb-S and σb-S relationships were found to be independent of αS/αt for the scCO2-water system in carbonate and silicate porous media. Nevertheless, the εb and σb values decrease as the water saturation decreases in the two porous media samples. While εb decreases with increase in temperature in silica sand, the trend in the limestone showed a slight increase with temperature, especially at high water saturation. Also, the εb-S relationship is shown to be affected by pressure in silica sand increasing with the pressure of the domain. On the contrary, the σb-S relationship increases as the temperature increases with more significance at higher water saturation in the silica sand sample. This work further demonstrated the application of a membrane in the monitoring of the CO2 in geological sites used for carbon sequestration. Commercial silicone rubber coupled with a pressure transducer showed potential in the detection of CO2 leakage from geological sites. The response of the device in terms of the mass of permeated gas, permeability and gas flux were investigated for both CO2 and N2. In addition, the monitoring of potable water contamination in a shallow aquifer by the migrating or leaking of CO2 is demonstrated with the combination of the pH analysis, geoelectrical measurement techniques and the membrane-sensor system. Overall, the work in this PhD research demonstrated robust applications of two-phase systems'characterization parameters under different scenarios in the porous media. Implications of the findings in this work to the monitoring and control of two-phase systems in porous media are expatiated.

Increasing use of engineered nanomaterials presents concerns as some nanoparticles appear to be harmful to both human health and the environment. Effective treatment methods are required to remove problematic nanoparticles from (waste)water streams. Porous media filtration, commonly used for the removal of particulate matter, shows promise for nanoparticle treatment. The goal of this work is to investigate the potential of porous media filtration for the abatement of nanoparticles from aqueous waste streams. To this end, an automated method was developed that allows real-time and in-situ monitoring of nanoparticle transport and retention in porous media using online measurement of UV-visible absorbance or fluorescence. Development of fluorescent-core nano-silica (n-SiO₂) in controllable sizes provided an excellent tracer for nanoparticle transport in porous media. Measurement of n-SiO₂ by destructive techniques is complicated by high natural Si background levels. Fluorescence monitoring enables real-time measurement, facilitating rapid evaluation of n-SiO₂ transport. Synthesized n-SiO₂ remain in their primary sizes making an evaluation of the behavioral change of particles due to transition into the "nano" range possible. A comparison of the role of particle size on transport in porous media displayed the importance of particle number concentration as the dominance of site-specific adsorption may be obscured by simple mass concentration evaluation.T he effectiveness of different bed materials, namely, sand, activated carbon (AC), and diatomaceous earth (DE), for the removal of TiO₂ nanoparticles (n-TiO₂) from aqueous streams was investigated. DE proved promising for n-TiO₂ capture shown by its high bed capacity (33.8 mg TiO₂ g⁻¹(medium)) compared to AC (0.23 mg TiO₂ g⁻¹(medium)) or sand (0.004 mg TiO₂ g⁻¹(medium)). The presence of organic and synthetic contaminants produced varying effects on n-TiO₂ retention, mostly due to either enhanced electrostatic or steric interactions. Application of a process simulator combining physical straining with site-specific interactions, delineating physisorption from chemisorption and diffusion limited interactions, enabled the accurate fit of n-TiO₂ transport in sand, AC and DE. The fitting process revealed the advantage of DE due to increased physisorption and physical straining of n-TiO₂. Modeling of this system afforded the elucidation of controlling retention mechanisms and provides a basis for future scaling and system design.

Des polymères à base de méthacrylate de poly(oxyde d'éthylène) (PEOMA) avec des chaînes pendantes PEO (Mn = 300 ou 950 g mol-1) ou des copolymères de PEOMA300 et d'acide méthacrylique (AMA) ont été synthétisés par polymérisation radicalaire contrôlée par les nitroxydes en utilisant une alkoxyamine (BlocBuilder®) comme amorceur en présence de SG1 et d'une faible quantité de styrène. Les copolymères à base de PEOMA300 et d'AMA sont thermo- et pH-sensibles. Les deux types de macroalkoxyamines ont été utilisés pour amorcer la copolymérisation en émulsion du méthacrylate de n-butyle et du styrène et former, par auto-assemblage induit par la polymérisation, des particules composées de copolymères à blocs amphiphiles, en absence ou présence de particules de silice. En absence de silice, des particules stabilisées de façon stérique ou électrostérique ont été formées. La polymérisation présente les caractéristiques d'une polymérisation contrôlée avec néanmoins la formation d'une faible proportion de chaînes mortes. L'effet du pH, de la force ionique et de la nature ou de la concentration des macroalkoxyamines sur la cinétique de polymérisation et la morphologie des particules a été étudié, et des sphères, des vésicules ou des nanofibres ont été obtenues. Les macroalkoxyamines à base de PEO s'adsorbent sur la silice via la formation de liaisons hydrogène entre les chaînes PEO et les groupes silanol. La synthèse de copolymères à blocs en surface de la silice a conduit à la formation de particules hybrides de différentes morphologies (bonhomme de neige, multipodes, framboise, coeur-écorce, têtard, mille pattes) liées à la taille de la silice, au pH et à la nature du macroamorceur
Water-soluble brush-type polymers composed of poly(ethylene)oxide methacrylate (PEOMA) units with PEO side groups of various chain lengths (Mn = 300 and 950 g mol-1) or of PEOMA300 with methacrylic acid (MAA) were synthesized by nitroxide-mediated polymerization using an alkoxyamine initiator (BlocBuilder®) and SG1 nitroxide in the presence of a low amount of styrene. The PEOMA300-MAA based copolymers showed a dual temperature/pH response. The two series of macroalkoxyamines were used in aqueous emulsion copolymerization of nbutyl methacrylate and styrene leading to the formation of particles composed of amphiphilic block copolymers through polymerization-induced self-assembly, in both the absence and presence of silica. The experiments performed in the absence of silica particles resulted in the formation of sterically or electrosterically stabilized latexes. The polymerization exhibited all the features of a controlled system with however the presence of a small proportion of dead chains. The effect of pH value, ionic strength and type and concentration of the macroalkoxyamine initiator on polymerization kinetics and latex morphologies was investigated. Depending on the reaction conditions, spherical particles, vesicles or nanofibers were successfully prepared. The PEO-based macroalkoxyamines were shown to adsorb on the silica surface via hydrogen bond interaction between PEO and the silanol groups. This enabled block copolymers to be generated in situ on the silica surface leading to hybrid particles with snowman, raspberry, daisy, core-shell, “tadpole-” and “centipede-” like morphologies depending on the silica particle size, pH value and type of macroinitiator

Abstract Ceramic matrix composite (CMC) has better durability at high temperature and lower material density, as compared to nickel-based super-alloys which have been the standard material for hot section components of aero-engines. Among the CMC materials, SiC-SiC CMC is especially promising with its superior mechanical property at higher temperature. It, however, inevitably needs environmental barrier coating (EBC) to protect the substrate against oxidation. The EBC also needs to have other functions and to meet various requirements. One such very critical requirement is the resistance to sand erosion, although the issue hasn’t been investigated well so far. The primary contribution of this work is to reveal the erosion resistance of the CMC+EBC material with wind tunnel test data of good quality and to demonstrate what erosion behavior the material exhibits in turbine cascade under particle-laden hot gas stream. In the present work, erosion tests were first carried out in a testing facility with erosion media of 50 microns silica sand. The tests were conducted under flow velocity of 225 m/s and temperature of 1311 K to simulate typical aero-engine conditions and impact angles of 30, 60, and 80deg were investigated. The obtained data showed a typical brittle erosion mode, where the erosion rate had a positive dependence on the impact angles. A typical erosion model, Neilson-Gilchrist model, was applied to correlate the data and the model was shown to have a good agreement with the experimental data once it was properly calibrated. Then, the numerical computation solving particle-laden flow was carried out to predict three dimensional flow field and particle trajectories across the target turbine cascade. The erosion profile along the airfoil was calculated based on the obtained trajectories and the calibrated erosion model. The trajectories showed that the particles mostly impinged the airfoil pressure surface first and then the rebounded particles attacked the opposite suction surface as well. Accordingly, the predicted erosion profile showed a broad erosion band across the pressure surface and also some slight erosion peak at around the mid-chord of the suction surface.

ABSTRACT With their abundancy and high-quality, it is predicted that fossil fuels will remain as the main resource that will meet the global energy demand in the several upcoming decades. Developments in hydrocarbon recovery technologies, both from conventional and unconventional reservoirs, have substantially contributed to the overall production levels in recent years. However, recovery factors obtained by using the current methods are still considered to be insufficient, and the companies have been looking for new materials and methods to enhance the efficiency and amount of recovery. One of the major issues related to low recovery factors is low permeability of reservoirs. Existence of blockages in pore throats and high level of heterogeneity lowers the mobility of hydrocarbons. In this study, we discuss development of an innovative material to be used as an additive in reservoir injection fluids to remove pore blockages in order to enhance the recovery levels. This additive material is made of pressure-sensitive microspheres loaded with solvents, which can (i) easily disperse in the injection fluid and travel to the low-permeability regions, (ii) break under pressure and confinement to release solvents, and (iii) remove blockages by targeting surroundings, especially asphalt-based particles and grains. This approach relies on the breakage of microcapsules in the confined region and release of the solvents to target blockages in porous media. In other words, the developed microspheres improve permeability of reservoirs as a result of pressure- and confinement-dependent breakage and release of solvents. Preparation of these microspheres was achieved by the encapsulation of solvent (toluene) emulsions in silica-based solid shells. Structure and stability of the solvent-loaded microspheres were examined using a variety of analytical techniques including UV-vis spectroscopy, optical microscopy, scanning electron microscope (SEM) and dynamic light scattering (DLS). It was found that the prepared microspheres possessed smooth surfaces with shell thicknesses in the range of 100-150 nm. Additionally, sand column tests were performed to evaluate the recovery potential of injection fluids in presence of solvent-loaded microspheres. It was shown that the use of solvent encapsulated in microspheres doubled the recovery factor of heavy oil compared to that of free solvent dispersed in the injection fluid. Such enhancement in the recovery factor was related to the release of solvents in localized areas, i.e., confined regions, as a consequence of breakage of microspheres. This novel approach of delivering solvents to low-permeability regions provides a significant driving force to eliminate pore blockages to facilitate mobilization of hydrocarbons trapped in confined spaces.

Experimental studies of turbine engine sand, dust, and ash ingestion have shown that certain constituents, typically those containing Calcium, Magnesium, Aluminum, and Silicon (CMAS) compound minerals and/or Chlorides and Sulfates, are particularly detrimental to engine turbine components. These reactive media undergo a phase change from solid to semi-solid as they pass through the combustion section of the engine under certain conditions characterized by size and mass. The phase change allows them to adhere to various turbine components including but not limited to stator vanes, rotor blades and shrouds. Unfortunately, with no on-board sensing technology the only warning signs that the flight crew has to an impeding airborne particle ingestion problem are lagging indicators. Hence, a sensor system that can measure the composition, size and concentration of particles being ingested by a gas turbine while in flight can provide pilots the warning they need to avoid damage mechanisms, both in the military where operational limits are always pushed to the maximum, and in the commercial area where safety is paramount. The current paper reports on the development of an in-situ sensor system that can be integrated at several places within an engine (e.g. aircraft inlet, engine inlet, engine bypass, engine gas path) with minimum modifications and provide measurements of composition, size and concentration for particles ingested by the engine.

Abstract Restructuring of the electric utility industry has received much attention in the national media as higher electric rates have been experienced this year in major population centers such as San Diego, CA and Westchester County, NY. Further, the lack of adequate electric capacity (and/or the ability to transmit the electricity) has continued to plague major metropolitan areas such as Detroit, MI and Silicon Valley. What role does waste to energy have in helping solve these problems? This paper will discuss the real life experience of a waste to energy project (Bristol, CT Resource Recovery Facility) in the rapidly changing world of electric deregulation. When Connecticut passed its restructuring legislation in 1998 (Public Act 98-28), no one realized how much effort would have to be spent at the agency level to preserve and protect existing power purchase agreements, especially those with “above market” pricing structures. In a state such as Connecticut where the adopted legislation was considered very favorable to private power producers such as waste to energy, many surprises have occurred during the implementation of the legislation. Understanding how Connecticut’s electric restructuring legislation has been implemented will help those with interests in any waste to energy, landfill gas, biomass or other renewable power source be better prepared to manage similar state and federal legislative initiatives.

Soil water wettability or water repellency is a phenomenon that can affect infiltration and, ultimately, runoff. Thus, there is a need to develop a model that can quantitatively capture the influence of water repellency on infiltration in a physically meaningful way and within the framework of existing infiltration theory. The analytical model developed in this study relates soil sorptivity (an infiltration parameter) with contact angle (a direct measure of water repellency) for variably saturated media. The model was validated with laboratory experiments using a silica sand of known properties treated to produce controlled degrees of water repellency. The measured contact angle and sorptivity values closely matched the model‐predicted values. Further, the relationship between the frequently used water drop penetration time test (used to assess water repellency) and sorptivity was illustrated. Finally, the direct impact of water repellency on saturated hydraulic conductivity was investigated due to its role in infiltration equations and to shed light on inconsistent field observations. It was found that water repellency had minimal effect on the saturated hydraulic conductivity of structureless sand. A quantitative model for infiltration incorporating the effect of water repellency is particularly important for post‐fire hydrologic modeling of burned areas exhibiting water repellent soils.