The concept of creating heterogeneous structures by nanocasting techniques from a combination of several homogeneous surfactant templated structures to model reservoir rock properties has not been approached prior to this research project, and will be used to test and provide better understanding of gas adsorption theories such as the pore blocking phenomenon (Seaton, 1991). Porous media with controlled pore sizes and geometry can be used to mimic a variety of reservoir rock structures, as it can be engineered to consist of a network of elements which, individually, could have either regular or irregular converging and diverging portions. The restrictions in these elements are called throats, and the bulges pores. Catalysts developed from a range of Nanotechnology applications could be used in down-hole catalytic upgrading of heavy oil. They could also be used as catalyst supports or to analyse the coking performance of catalysts. These studies will highlight the pore structure effects associated with capillary trapping mechanisms in rocks, and potentially allow the manipulation of transport rates of fluids within the pore structure of catalysts. Mercury-injection capillary pressure is typically favoured for geological applications such as inferring the size and sorting of pore throats. The difference between mercury injection and withdrawal curves will be used to provide information on recovery efficiency, and also to investigate pore level heterogeneity. Mercury porosimetry studies are carried out to provide a better understanding of the retraction curve and the mechanisms controlling the extrusion process and subsequently the entrapment of the non-wetting phase. The use of model porous media with controlled pore size and surface chemistry allows these two effects to be de-convolved and studied separately. The nanotechnology techniques employed mean that uncertainty regarding exact pore geometry is alleviated because tight control of pore geometry is possible. Trapping of oil and gas on a microscopic scale in a petroleum reservoir rock is affected by the geometric and topologic properties of the pores, by the properties of the fluids and by properties related to fluid-rock interaction such as wettability. Several distinct mechanisms of trapping may occur during displacement of one fluid by another in a porous media, however in strongly water-wet rocks with large aspect ratios, trapping in individual pores caused by associated restricting throats (may be/is) the most important mechanism of trapping. The results of the proposed research will be both relevant to the Irene Osagie Evbuomwan PhD. Thesis (2009) 9 oil and gas as well as the solid mineral sector for application as catalyst or catalyst supports. By providing a better understanding of the relationship between reservoir rock pore space geometry and surface chemistry on the residual oil levels, a more accurate assessment of the potential of a particular reservoir could be generated. The analysis of gas adsorption/desorption isotherms is widely used for the characterization of porous materials with regard to their surface area, pore size, pore size distribution and porosity, which is important for optimizing their use in many practical applications. Although nitrogen adsorption at liquid nitrogen temperature is considered to be the standard procedure, recent studies clearly reveal that the use of additional probe molecules (e.g. argon, butane, carbon dioxide, water, hydrogen, and hydrocarbons e.g. cyclohexane and ethane) allows not only to check for consistency, but also leads to a more comprehensive and accurate micro/mesopore size analysis of many adsorbents. Furthermore, significant progress has been achieved during recent years with regard to the understanding of the adsorption mechanism of fluids in materials with highly ordered pore structures (e.g., M41S materials, SBA-15). This has led to major improvements in the pore size analysis of nanoporous materials. However, there are still many open questions concerning the phase and sorption behaviour of fluids in more complex pore systems, such as materials of a heterogeneous nature/differing pore structures, which are of interest for practical applications in catalysis, separation, and adsorption. In order to address some of these open questions, we have performed systematic adsorption experiments on novel nanoporous materials with well defined pore structure synthesised within this research and also on commercial porous silicas. The results of this study and experiments allow understanding and separating in detail the influence of phenomena such as, pore blocking, advanced condensation and delayed condensation on adsorption hysteresis and consequently the shape of the adsorption isotherms. The consequences of these results for an accurate and comprehensive pore size analysis of nanomaterials consisting of more complex nanoporous pore networks are also investigated.

It has been generally recognized that the surface phenomena of the solid particles such as shrinking and swelling, water- holding capacity, water' movement, and cation exchange are important in understanding the physical properties of the soil. Clay is the most prevalent material in the colloidal fraction of many soils. Because of the complex nature of the surface of clays and the small size of the particles, the direct study of surface phenomena is difficult. Thermodynamic functions change in accordance with changes and organization within the system. Thus, an examination of the thermodynamics of surface phenomena provides some understanding of the reactions.

Smectite clay has been shown in studies over the past 20 years to sorb aflatoxin B1 (AfB1) in animal feed and thereby reduce its toxic influence on animals. In this study, 20 smectite samples were selected from industrial products or reference minerals. In the initial steps, it was shown that AfB1 entered the interlayer galleries of smectites and a 10-fold range in sorption ability was observed in a set of 20 smectite samples. Yet, it was not clear which clay properties (CEC, pH, base saturation) influenced this variation. In an effort to further explore properties that might influence the sorption of AfB1, three good sorbent samples were chosen from our set of 20 samples along with one sample of low sorption capacity. Those samples were fractionated into sand, silt, coarse clay (CC), and fine clay (FC) fractions. From all sample fractions, sorption isotherms and X-ray diffraction patterns were obtained. Additionally, a vermiculite and a palygorskite were examined with regard to sorption capacity. Concentration of smectite and their adsorption test suggest that differences in smectite composition are responsible for difference in sorption, not so much their relative abundance or other mineral phases. Initial infrared analysis indicates that weathered aluminous smectites, which have no octahedral iron or magnesium, belong to the poor AfB1 sorbents. Palygorskite and vermiculite are not effective sorbents. Based on the findings in this study, tentative quality criteria of sorbent selection for their use in animal feed were established. These criteria are: pH between 6.5 and 8.5, CEC > 75cmolc/kg, organic carbon < 2.5 g/kg, expression of XRD smectite peak and AlFeOHbending in FTIR and Langmuir adsorption capacity for AfB1 > 0.40 mol/kg.

In this project, three separate experiments were conducted to assess heavy metal removal from metal aqueous solutions and synthetic landfill leachate by adsorption using low-cost natural adsorbents. Fundamental batch investigations indicated that the 4.0-4.75 mm crushed mollusk shells and the Sphagnum peat moss were the best adsorbents for cadmium and nickel removal, respectively. Peat moss was also found to have the highest adsorption capacities for manganese and cobalt adsorption. The adsorption capacities of the peat moss and crushed mollusk shells used as natural adsorbents for the adsorption of cadmium and nickel from binary aqueous solutions in fixed-bed columns under continuous flow conditions were investigated. The life expectancy of each adsorbent in the fixed-bed columns was also assessed for different hydraulic loading rates. The flow rate of 1.5 mL/min (surface loading of 27.52 cm3/cm2•day) and bed depth of 15 cm were identified as the better operational conditions from the column testing. The results indicated that 47.9% and 42.7% cadmium and nickel removal efficiencies could obtained under these operational conditions, respectively. Finally, the peat moss and the crushed mollusk shells were packed in bench-scale down-flow fixed-bed columns to evaluate their adsorption capacities as natural low-cost adsorbents for the removal of heavy metals from aerated and non-aerated synthetic landfill leachate. The flow rate applied in this operation was 1.5 mL/min (surface loading of 27.52 cm3/cm2•day). Peat was found to have the best adsorption capacities in columns treating aerated synthetic leachate for cadmium (78.6%) and nickel (83.8%) removal efficiencies. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-01-31 22:37:34.381

No description available.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-04-10T14:03:59Z No. of bitstreams: 0 / Made available in DSpace on 2015-04-10T14:03:59Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-04-10T14:03:59Z No. of bitstreams: 0 / Made available in DSpace on 2015-04-10T14:03:59Z (GMT). No. of bitstreams: 0 / No presente estudo, material zeolítico sintetizado a partir de cinzas de carvão e modificado por surfactante catiônico foi utilizado na remoção do corante ácido laranja 8 (AL8) por processo de adsorção utilizando leito móvel e coluna de leito fixo. As matérias primas e os adsorventes foram caracterizados por diferentes técnicas, tais como: difração de raios-x, fluorescência de raios-X, entre outras. A adsorção do AL8 foi realizada por leito móvel com o objetivo de otimizar os resultados quando lançados em leito fixo. Os efeitos na adsorção do AL8 sobre zeólita foram comparados: (1) efeito dos contra-íons Br- e Cl- do surfactante usado na modificação da zeólita; (2) efeito do tipo de cinzas de carvão usada como matéria prima na síntese das zeólitas (leve e pesada). Os seguintes adsorventes foram utilizados no estudo: zeólita leve e pesada modificada por surfactante brometo de hexadeciltrimetilamônio (ZLMS-Br e ZPMS-Br) e zeólita leve modificada por surfactante cloreto de hexadeciltrimetilamônio (ZLMS-Cl). A cinética de pseudo-segunda-ordem descreveu a adsorção do corante sobre todos os adsorventes. O tempo de equilíbrio alcançado foi 40, 60 e 120 min para ZLMS-Br, ZLMS-Cl e ZPMS-Br, respectivamente. O equilíbrio de adsorção foi analisado pelas equações dos modelos das isotermas lineares e não lineares de Langmuir, Freundlich, Temkin e Dubinin-Radushkevivh (DR) e o critério de melhor ajuste foi avaliado usando as funções erros. O modelo DR ajustou-se melhor aos dados experimentais para o sistema AL8/ZLMS-Br, o modelo de Freundlich para AL8/ZLMS-Cl e Langmuir para AL8/ZPMS. Segundo Langmuir a capacidade máxima de adsorção foi 4,67 , 1,48 e 1,38 mg g-1 para ZLMS-Br, ZLMS-Cl e ZPMS-Br, nesta ordem. Nos estudos empregando-se colunas de leito fixo, os efeitos da concentração de entrada (20 - 30 mg L-1), vazão de alimentação (4,0 - 5,3 mL min-1) e a altura do leito (5,5 - 6,5 cm) sobre as características da curva de ruptura no sistema de adsorção foram determinados. Os modelos Bohart-Adams, Thomas, Yoon-Nelson foram aplicados aos dados experimentais para a previsão das curvas de ruptura e para a determinação dos parâmetros que caracterizam a coluna. Os modelos matemáticos de Thomas e Yoon-Nelson se ajustaram satisfatoriamenete aos dados das curvas de ruptura. A maior capacidade total de remoção do AL8 pela coluna de leito fixo apresentou o valor de 5,30 mg g-1 obtida com a concentração do corante de 30 mg L-1, altura do leito de 5,5 cm e uma vazão de alimentação de 5,3 mL min-1. Os ensaios de ecotoxicidade aguda utilizando o microcrustáceo Daphnia similis com o efluente bruto (AL8) e após tratamento com zeólita leve modificada com surfactante foram realizados com o propósito de avaliar evidências de uma possível contaminação quando lançados no corpo hídrico receptor. Os resultados obtidos neste estudo mostraram que as amostras do corante AL8 em solução aquosa não apresentou efeito tóxico e as amostras tratadas com ZLMS-Br apresentaram toxicidade. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Mycotoxins have become an important issue for the grain industry and animal producers with a growing interest in the decontamination and remediation of highly contaminated feedstuffs. Practical methods to detoxify mycotoxin-contaminated grain on a large scale and in a cost-effective manner are essential but not currently available. The most recent and promising approach to detoxify mycotoxin-contaminated grain is the use of non-nutritive adsorbents, which bind the aflatoxin and thereby reduce their absorption from the gastrointestinal tract. Humic acids are products of chemical and biological transformations of animal and plant residues and are widely distributed in nature. Humic acids have some therapeutic characteristics and a strong binding affinity for several compounds. A South African company developed an effective large-scale regeneration process for humic acids from coal, called oxihumate. This study evaluated the effectiveness of oxihumate to adsorb mycotoxins, for the purpose of developing it as a commercial mycotoxin binder to be used in the preventative management of contaminated poultry feedstuffs. The in vitro affinity and adsorption capacity of oxihumate to aflatoxin was evaluated and the efficacy of oxihumate as an aflatoxin binder in broiler feeds in vivo was determined. The data showed adsorptions of about 10.3, 7.4 and 11.9 mg aflatoxin B1/g oxihumate at pH 3, 5 and 7, respectively. Oxihumate adsorbed 1.2, 2.6 and 8.5 mg aflatoxin G2/g at pH 3, 5 and 7, respectively. Oxihumate supplementation at a concentration of 3.5 g/kg feed was effective in diminishing the growth inhibitory effects of aflatoxin and apparent protection was noted for some of the organ, haematological and serum biochemical changes associated with aflatoxicosis. These results suggest that oxihumate could alleviate some of the toxic effects of aflatoxin in growing broilers, and when used with other sound mycotoxin management practices, might prove beneficial in the preventative management of aflatoxin-contaminated feedstuffs for poultry. The improvement observed during this specific study was, however, not satisfactory enough to recommend oxihumate as a commercially available product. / Thesis (PhD (Animal and Wildlife Sciences))--University of Pretoria, 2007. / Animal and Wildlife Sciences / unrestricted

Hydrotalcite-like compounds are synthetic anionic clays that have outstanding adsorption and catalytic properties. Hydrotalcite nanoclays (Mg–Al layered hydroxides) were synthesized by co-precipitation method. Obtained solids were converted into mixed metal oxides by thermal decomposition at temperatures up to 723 K. High adsorption and reconstructive properties of the mixed metal oxides allowed incorporating metal ions in their structure. Thus, these materials can be used as ion traps from aqueous media. Cesium ions were incorporated into hydrotalcite lamellar structure by impregnation method. Effects of different loads of Cs+ and adsorption times on the material properties were studied. The materials were characterized by X-ray diffraction, surface area analysis, scanning electron microscopy, energy dispersive X-ray spectrometry for obtaining a localized chemical analysis, and temperature-programmed desorption of CO2 for measurement of basic sites density. The amounts of metal incorporated in the structure was high enough due to small size of Cs+ ion. Synthetized materials also demonstrated high concentrations of strong surface basic sites formed through a synergistic effect of Cs and Mg ions. Basic properties of Cs-containing hydrotalcites enable their potential use as catalysts of base-catalyzed reactions.

No / A new technique using ozone loaded on adsorbents for industrial waste-water treatment has been investigated. This is a three-step process: ozone adsorption on a fixed bed column; water treatment on the bed loaded with ozone; and finally drying/ regeneration of the wet bed. Silica gel of mean particle size of 1.5 mm has been tested for ozone loading capacities followed by water treatment, both at ambient temperature. The mechanisms of the mass transfer process during ozone loading and water treatment have been established. The drying of the adsorbent using vacuum and dry air is feasible, but it is a time-consuming operation. A design procedure is described for the whole system.