A study of the extraction of cobalt II ions from an aqueous growing drop into a continuous medium of di-2-ethylhexylphosphoric acid (D2EHPA) is made. The apparatus for this technique is described and a flow injection analysis method for measuring the cobalt remaining in the aqueous phase has been developed. In this study the feed concentration of cobalt has varied between 8.48 x 10-3 and 16.97 x 10-3 mole 9-1. The D2EHPA held in n-heptane, has been altered between 0.143 and 2.41 mole P. Also, pH has been adjusted between 3.10 and 4.44. The principal temperature applied to this study was 25 ±0.5*C. Acetate buffers have been used, but it is shown by calculation that about 70% of the cobaltous ion is in an uncomplexed form. The kinetics of the extraction have been modelled using a method based upon reaction in an aqueous zone near to the liquid-liquid interface with diffusion of species towards and away from the interface. This model provided a fundamental parameter 01 which incorporates the chemical rate constant kR, the D2EHPA partition coefficient PHR, the acid dissociation constnat KD for D2EHPA and the metal ion diffusivity in the interface diffusion region. The results have been compared with those of other workers who studied the transfer of cobalt into an organic drop from an aqueous continuum. The diffusion controlling film is the aqueous one. The rate constant for, the extraction reaction equation is, from this work, kR - 106.34 M3 kmol-1 sec-1 which can be compared with that found by another worker using the reverse transfer system, i. e. kR - 106.18 m3 kmol-I sec-i. . Finally, the mass transfer coefficients were found to change with varying feed concentrations and pH, this is also in agreement with other workers who have studied different liquid-liquid systems.

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New approaches to the analysis of trace metal concentrations in seawater have the potential to advance the field of oceanography and provide a more comprehensive understanding of the marine biogeochemical cycles of trace metals and the processes regulating these cycles. Traditional oceanographic methods of trace metal analysis were developed several decades ago using benchtop liquid-liquid extraction (Danielson et al., 1978; Kinrade and Van Loon, 1974; Miller and Bruland, 1994; Moffett and Zika, 1987). More modern techniques utilize flow based solid phase extraction to eliminate the high ionic strength matrix to determine dissolved concentrations with great accuracy and precision but do not allow for the determination of metal speciation in solution (Wells and Bruland, 1998). The method developed here measures oceanographically relevant concentrations of copper (Cu) in seawater via chemiluminescence (Marshall et al., 2003 and Coale et al., 1992) and micro-molar levels of silver (Ag) colorimetrically after automated liquid-liquid extraction. The Zone Fluidics (Marshall et al., 2003) analyzer for trace Cu determined SAFe D2 standard seawater (www.geotraces.org) to be 1.77 nM Cu comparable to the expected consensus value. The method was used to determine dissolved Cu depth profiles for major stations along the Line P Time-series transect (48N 125W - 50N 145W) in the Pacific Ocean during February 2011. This method consumes less than 200 µL of sample and reagents and is performed in less than 3 minutes making it suitable for ship or lab based analysis. / Graduate / 0485 / 0425 / cschwang11@gmail.com

<p> This report covers two topics. First is the development of computer programs to carry out the calculations needed to determine the control policy to bring a process from one set of steady state conditions to another. Examples of the implementation of control policies for a liquid-liquid extraction column are included. Suggestions have been made for means of decreasing the calculation time and for means of increasing the size of problem that may be solved. </p> <p> The second part discusses an initial project of using a Supernova computer as a direct control computer. Characteristics of direct digital control are illustrated using an analog simulation of the extraction unit as the controlled process. </p> / Thesis / Master of Engineering (MEngr)

With many processing advantages, electrophoretic deposition (EPD) has been chosen as the fabrication technique for inorganic-organic nanocomposites. However, before the EPD process, avoiding the particles agglomeration is considered a necessary perquisite for the success of fabrication. In this research, two different liquid-liquid extraction methods, one is one-step and the other is two-step, were developed to solve the agglomeration problem of inorganic particles. The adsorption mechanisms of the extractors and extraction mechanisms were investigated during this work. The strong adsorptions provided by –OH groups of the extractors and further Schiff base reaction allowed for the process of extraction. In the fabrication, polyelectrolytes acted as the film forming and charging agents. Relatively stable suspensions with extracted inorganic particles were prepared for the EPD of inorganic-organic nanocomposites. The thickness of deposited films is proportional to the concentration of the suspension and deposition time. With the addition of flame retardant inorganic particles, the prepared nanocomposite films showed an enhanced flame retardant performance. / Thesis / Master of Applied Science (MASc)

The overuse of antibiotics in agriculture is an emerging concern, due to their potential detrimental impact to the environment. This study focuses on exploring antimicrobial properties of lignin derived compounds. Lignin is of interest as a feedstock to replacing some petroleum-based chemicals and products because it is the most abundant source of renewable aromatic compounds on the planet. Two lignin rich streams, residues from the enzymatic hydrolysis of dilute acid and alkaline pretreated corn stover, were decomposed via pyrolysis and hydrogenolysis, respectively. The resulting liquid oils were subjected to sequential extractions using a series of solvents with different polarities. Chemical compositions of the extracted fractions were characterized through HPLC and GC/MS. These extracted compounds were screened against Saccharomyces cerevisiae (S. cerevisiae), Escherichia coli, and Lactobacillus amylovorus for antimicrobial properties. Six lignin model monomers: guaiacol, vanillin, vanillic acid, syringaldehyde, 2,6-dimethoxyphenol, and syringic acid were compared to the oils and extracted fractions for antimicrobial properties. Development of lignin-derived chemicals with antimicrobial properties could provide a novel use for this underutilized natural resource.

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