The purpose of this investigation was to determine the effect of the positions and the molecular weight of surfactant hydrophilic functional groups on the rate of gas absorption. A quiescent unsteady-state absorption apparatus was used with carbon dioxide and water as the absorption system. Three surfactants with hydroxyl groups were selected for study, namely, n-octanol, 4-octanol and lauryl diglycol amide. Preliminary absorption tests were made using pure deionized water to determine the diffusion coefficient for the system. A value of 1.93 ± 0.05 x 10⁻⁵ square centimeters per second was obtained. The absorption tests were repeated with the three surfactant solutions at different concentrations. Then the interfacial resistance for each solution was calculated. The results of the surfactants were compared with each other and were also compared with the results of lauryl diethanol amide previous investigated. The octanol with hydroxyl group at a branched position was found to cause a higher interfacial resistance than those with hydroxyl groups at the end of the hydrophobic chain. It was also concluded that increasing the molecular weight of the hydrophilic group decreased the interfacial resistance. / Master of Science

Gas absorption may be defined as the transfer from a gas to a liquid of one or more components of a gaseous mixture by means of solution in a liquid. This is accomplished by bringing the two phases together, with a large amount of interfacial surface, in an economical manner for commercial use. Much is lacking in knowledge of the theory of gas absorption. This lack of knowledge and the wide variety of purposes and specifications have caused many types of absorption equipment to be designed, built and used. The objective in all causes has been to increase the surface of contact between the gas and the liquid at low installation cost and with low operating costs. The most common type of absorption equipment is the packed tower. It consists, essentially, of a vertical shell filled with an inert packing material. Absorption is accomplished by countercurrent operation, the solvent being allowed to trickle down over the packing material while the gas passes up through the wetted packing. The tower packing is the fundamental consideration in improving the efficiency of the equipment. A packing material should have a low resistance to gas flow so as to give low maintenance costs, a high absorption capacity and low costs of installation. In any case, the packing that most completely fills the requirements should be used. It is the purpose of this investigation to make a study of the characteristics of operation of copper knit-metal cloth, in comparison to Raschig rings, when used absorption tower packings. / Master of Science

This study presents the results from laboratory investigations of the capacity of kaolinite to adsorb heavy metals including copper, nickel, cadmium, and lead. Kaolinite is a clay commonly found in suspended solids and sediments in natural water systems. The purpose of the study was to evaluate the validity of the competitive adsorption equation presented by weber in describing metal adsorption on kaolinite. This equation describes adsorption competition among the components of a mixture of solutes. Adsorption studies were conducted for single and mixed metal systems. Controlling factors considered include solution pH, clay dosage, and cation competition. The investigation demonstrated that the competitive adsorption equation is a valid and useful equation for describing the adsorption of mixed metal systems on kaolinite. The equation may be used to predict equilibrium metal concentrations in mixed metal systems. The results of the study also indicated that the rate of adsorption of the metals on kaolinite was very rapid. Equilibrium was complete within thirty minutes of the addition of the metals to the clay. / Master of Science

Hydrophobic organic contaminants released into the subsurface can become sorbed to the soil matrix. The sorbed compounds may slowly leach into the groundwater, providing a long-term source of contamination. Bioremediation has been cited as a potential clean-up strategy for residual organics in soils. At present, factors which control biological utilization and retention of organic contaminants in the subsurface are poorly understood. The purpose of this study was to investigate how the adsorption/desorption and biodegradation processes interact to control the distribution and biological fate of subsurface contaminants. Batch soil microcosms were used to evaluate the sorption of a chlorinated aromatic compound [2,4,6-trichlorophenol (TCP)] to mineral soils, organic soils, and dissolved macromolecules (humic acid). Microbial utilization of 2,4,6-TCP was then evaluated after addition of a bacterial culture previously acclimated to the substrate. Biodegradation was evaluated by production of ¹⁴CO₂ and disappearance of 2,4,6-TCP from the sorbed and solution phases. Size exclusion chromatography was used to distinguish between free 2,4,6-TCP in solution and 2,4,6-TCP bound to humic acid in solution. Sorption of 2,4,6-TCP to mineral surfaces was rapid but sorption to organic soils varied with contact time. Most 2,4,6-TCP sorption to organic soils occurred during the first few days of contact with the soil. However, the sorption rate gradually decreased with time and 2,4,6-TCP continued to sorb for weeks at a reduced rate. The amount of 2,4,6-TCP which sorbed at the slower rate was dependent upon the organic matter content of the soil. Desorption of 2,4,6-TCP from organic soils was similar to adsorption; however, it appeared that slow desorption took longer than slow adsorption. Humic acid in solution formed an additional phase to which 2,4,6-TCP sorbed. The sorption capacity of dissolved humic acid was a function of the humic acid concentration. Higher concentrations of humic acid had lower sorption capacities when normalized for total organic carbon content. The mineralization rate of 2,4,6-TCP by Pseudomonas aeruginosa was dependent upon the initial substrate concentration. Total mineralization of 2,4,6-TCP by P. aeruginosa decreased in the presence of organic soils. However, mineralization rates were elevated in organic soils compared to mineral soils after 5 days of incubation. This was attributed to an influx of substrate into solution from an initially sorbed state. Total mineralization of 2,4,6-TCP in humic-containing solutions was reduced by 5-10 % over humic-free solutions. The bioavailability of 2,4,6-TCP was greatly reduced in the sorbed state. Biodegradation of unbound 2,4,6-TCP in solution was very rapid while biodegradation of 2,4,6-TCP sorbed to organic soil or to dissolved humic acid was much reduced. Desorption of most 2,4,6-TCP from soil was rapid, thereby becoming available to acclimated bacteria. However, a small quantity of 2,4,6-TCP desorbed from organic soil and dissolved humic acid very slowly and became available for biodegradation at a rate limited by desorption. / Ph. D.

Soil column studies were performed on a chromium contaminated soil from the United Chrome Products Superfund Site currently undergoing a pump-and-treat cleanup process. The goal of the research was to provide insight into the feasibility of chemically changing the injection fluid of the pump-and-treat system to enhance hexavalent chromium (Cr(VI)) mobility. The parameters tested were pH, ionic strength, and competitive anion type and concentration. Ionic strength effects were investigated by adjusting the NaCl concentration of the extracting solution and by observing the influence of varying anion concentrations on desorption (bicarbonate, sulfate, and phosphate). The results indicated that high ionic strength solutions slow the rate of Cr(VI) desorption. This possibly indicates most of the Cr(VI) was in pore water solution and was adsorbing, slowing the removal process. Cr(VI) desorption was fastest for distilled water solution followed by competitive anion/distilled water solutions. The high ionic strength extracting solutions, 0.05 M and 0.10 M NaCl, had the slowest Cr(VI) desorption rates. Effluent pHs dropped as the ionic strength was increased (increasing NaCl concentrations) which was attributed to a Na-H exchange. Increased concentrations of bicarbonate, sulfate, and phosphate resulted in only small pH differences in the effluent of less than 0.5 pH units. The effect of pH was investigated by varying the pH of the 0.01 M NaCl solution with strong acid and base and by varying the pH of phosphate competitive anion solutions. The effects of changing 0.01 M NaCl solution pH were inconclusive. Differences between Cr(VI) desorption rates for the soil columns with adjusted influent pHs were small. Cr(VI) desorption curves and column effluent pH values for phosphate solutions of varying influent pH values were nearly identical, indicating that soil buffering and effluent pH are more important factors than influent pH in achieving Cr(VI) desorption. Nitrate, bicarbonate, sulfate, and phosphate were investigated to determine the effect of various competitive anions on Cr(VI) desorption. The effectiveness of each anion at extracting Cr(VI) from soil appeared to follow the order of adsorption affinity to the soil. / Graduation date: 1992

Graduation date: 1993

Thesis (M.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

The objectives of the study were to investigate the sorption and degradation of a glucuronide conjugated natural hormone, 17β-estradio1-3-glucuronide (E2-3G), and its estrogenic metabolites in soil-water systems. Radiolabeled E2-3G was first synthesized in the laboratory. Soil-water batch experiments were then conducted using natural and sterilized topsoil (0-6 cm) and subsoil (18-24 cm) with the radiolabeled E2-3G to investigate the effects of soil organic matter content and microbial activity. The aqueous dissipation of 14C in the batch experiments followed a biphasic pattern with an initial rapid dissipation phase followed by a second slower phase. Significant differences in total aqueous 14C dissipation were observed for the different initial concentrations for both soils, with greater persistence of intact E2-3G at higher initial concentrations. / National Science Foundation [Grant No. 0730492]

Les impacts environnementaux majeurs de l'agriculture sont associés à l'eutrophisation des eaux de surface causée par un enrichissement excessif en nutriments (azote et phosphore) et à la contamination des eaux souterraines par les ions nitrate. L'objectif principal de ce projet de doctorat est l'utilisation de matériaux mésoporeux fonctionnalisés à base de silice pour l'adsorption des ions phosphate et nitrate contenus dans des solutions acqueuses synthétiques simulant les effluents d'origine agricole. Trois matériaux mésoporeux (MCM-41, MCM-48 et SBA -15) fonctionnalisés avec des groupements ammonium par la technique de greffage et de co-condensation ont été synthétisés, caractérisés puis testés en mode discontinu. Les conditions opératoires ont été optimisées aussi en mode discontinu. L'équilibre et la cinétique d'adsorption ont été modélisés. Finalement, l'adsorption des ions nitrate et phosphate a été menée en mode d'écoulement continu pour simuler les conditions opératoires à l'échelle industrielle.

D. Tech. Chemical Engineering / Aims of this research project was to add value to largely wasted South African sawdust by development of low-cost AC of high efficiency for removal of toxic Cr (VI), phenol and glutaraldehyde from dilute aqueous media. The main objectives of the research project were: a) To develop low-cost AC based on South African P. patula sawdust using economical physical superheated steam activation.Characterization of carbon samples for selection of optimum preparation conditions for development of low-cost AC of effective microporosity mesoporosity and surface functionality for enhanced adsorption capacity of Cr (VI) and/or phenol and/or glutaraldehyde from dilute aqueous solution. Acid-amine surface groups modification of optimally developed AC for further enhancement of adsorption capacity for mixed polarized glutaraldehyde molecules from aqueous solution. b) To evaluate the aqueous phase batch adsorption properties of developed AC for Cr (VI) and phenol and, of acid-amine modified developed AC for glutaraldehyde. Determination of optimum pH for adsorption; accurate adsorption isotherm modelling for determination of maximum adsorption capacity, comparison of maximum adsorption capacities for Cr (VI) and phenol of developed AC with commercial AC and literature ACs, and attempt to establish average micropore size for enhanced capacity for Cr (VI) and phenol from dilute aqueous solution.Kinetics reaction and diffusion modelling for determination of adsorption rate constants and diffusion parameters; and determination of adsorption thermodynamic parameters.Evaluation of equilibrium selectivity of developed AC for Cr (VI) and/or phenol in binary aqueous solutions. c) To evaluate aqueous phase fixed-bed adsorption characteristics of developed AC for single Cr (VI) and mixed solution using Rapid Small Scale column Tests (RSSCTs). Generation of breakthrough curves at optimum adsorption conditions for evaluation of column performance indicators at different process conditions, bed regeneration-reusability potential, and dynamic adsorption selectivity of developed AC for Cr (VI) from solution of base metals. Determination of column diffusion parameters; accurate mass transfer and empirical modelling of breakthrough data; determination of applicable RSSCT scaling equation; and optimization of breakthrough data for accurate RSSCT scale-up.