Call number: LD2668 .T4 1957 C48 / Master of Science

Call number: LD2668 .T4 1960 C37

Chitosan has been proposed as a "natural" coagulating agent to solve wastewater problems. The main hindrance in this commercial chitosan application has been its low cost effectiveness. The hypothesis in our research is that chitosan complexes with natural polyanions is more effective than chitosan alone, particularly in recovering low concentration proteins from food processing wastewater. Chitosan (Chi) was reacted with alginate (Alg), pectin (Pec) and carrageenan (Car) ex-situ to obtain chitosan-polyanion complexes (Chi-Pol). Analysis by Fourier Transform Infrared (FTER) spectroscopy confirmed electrostatic interactions as the mechanism for complex formation. Scanning electron microscopy revealed a tight, non-porous structure except for the porous Chi-Car complex. Tests with a bovine serum albumin solution revealed low adsorption rates with slightly higher values for Chi-Car suggesting the need for an improved complexation method. Chi-Pol complexes prepared in-situ at different monomeric weight ratios (MR) were evaluated using pH 6 adjusted Cheddar cheese whey and surimi wastewater (SWW). Complexes used at 30 mg complex/L whey showed higher turbidity reductions than at 10 mg/L. MR had no significant effect on turbidity reduction except for Chi-Alg at 30 mg/L; the value (72 %) at MR = 0.2 was higher than for MR = 0.8. UV-Vis spectroscopy confirmed in-situ complex formation with a preference for the adsorption of specific whey protein fractions. Complexes formed at 0.2 and 0.8 MR were evaluated at two concentrations for the treatment of SWW. Tests at 50 mg/L showed a turbidity reduction of up to 97 % at 24 h with a 81-90 % recovery of SWW proteins. At 150 mg/L, similar efficacy was achieved in only 1 h with turbidity reductions ranging 94-99 % and 78-94 % protein recovery. FTIR analyses confirmed the adsorption of proteins as indicated by similarities in the three amide bands for Chi-Alg recovered solids and untreated SWW. Differential scanning calorimetry (DSC) was employed to study interactions of SWW proteins and Chi-Alg complexes. Untreated and complex bound SWW proteins revealed single exothermic peaks at 23.3 and 38.0°C, respectively. This suggested Chi-Alg and SWW protein interactions increased the thermal stability of SWW proteins. However, further thermal analysis studies are needed to confirm this finding. / Graduation date: 2001

Interactions between proteins and contact surfaces can have important implications in the food industry. Such interactions contribute to the course of fouling of membrane surfaces and they appear to mediate bacterial and spore adhesion to some degree as well. In addition to protein and solution properties, interfacial behavior is strongly influenced by contact surface properties. Among these, hydrophobicity and the potential to take part in acid-base interaction have received considerable attention, but in a quantitative sense we know very little about their respective influences on protein adsorption. It was the purpose of this research to quantify the equilibrium adsorptive behavior of the milk protein β-lactoglobulin as it is influenced by the presence of different contact surface functional groups. Monocrystalline and polished silicon surfaces were modified to be hydrophilic by oxidation and hydrophobic by silanization with dichlorodiethylsilane (DDES), dichlorodimethylsilane (DDMS), and dichlorodiphenylsilane (DDPS), each used at concentrations of 0.82, 3.3, and 82 mM. Surface hydrophobicities were evaluated with contact angle methods. Adsorption isotherms were constructed after allowing each modified silicon surface to independently contact β-lactoglobulin (0.01 M phosphate buffer, pH 7.0) at concentrations ranging between 200 and 2000 mg/L for eight h at room temperature. Surfaces were then rinsed and dried. Optical properties of the bare- and film-covered surfaces, necessary for calculation of adsorbed mass, were obtained by ellipsometry. Plots of adsorbed mass as a function of protein concentration exhibited attainment of plateau values beyond a protein concentration of about 200 mg/L. At high silane concentration, the plateau values associated with surfaces exhibiting ethyl groups were observed to be greatest followed by those exhibiting phenyl, methyl, then hydrophilic (OH) groups. At the low DDMS and DDES concentrations (0.82 and 3.3 mM), adsorbed mass did not increase beyond that value recorded for the hydrophilic surface. This is likely due to some critical spacing of methyl and ethyl groups being required to produce a favorable hydrophobic effect on adsorption. For surfaces treated with dichlorodiphenylsilane, adsorbed mass increased with silane concentration. Apparently, a favorable acid-base interaction effected by the hydrophilic surface is inhibited by the presence of small amounts of methyl and ethyl groups, but somewhat less inhibited by the presence of phenyl groups because the latter have the ability to undergo acid-base interaction. / Graduation date: 1993

A significant advantage attributed to surge flow irrigation is that for the same volume of water applied the stream will advance farther along the furrow than with continuous flow. This potentially will reduce runoff and deep percolation which will improve uniformity and application efficiency where this advance phenomenon holds. The mechanism for improvement in advance time has generally been ascribed to surface sealing and surface layer consolidation. However, these phenomena do not satisfactorily explain improved advance times in sandy soils. Widely used infiltration equations which require the determination of empirical coefficients are unsatisfactory as predictors of infiltration conditions of intermittent wetting. The Green-Ampt model and a simple redistribution model are combined into an analytical model to predict infiltration under surge irrigation. The model results are compared to infiltration tests on soil columns of three soils of different soil textures. Also the model and the experimental results from the soil columns are compared to predictions made by two numerical solutions of the Richard's equation. One of the numerical models includes the effect of hysteresis by the use of Mualem's model to predict the variation of moisture content with potential, the other numerical model neglects the effect of hysteresis. A comparison of the analytical and the numerical models shows good agreement in their predictions for the soils and surge cycles tested. A comparison of predictions made by all three models shows good correlation to the experimental results. Although the number of tests done on the analytical model were limited it appears to be nearly as good a predictor of infiltration as the numerical models. The greatest strength of the analytical model is that while the numerical models took many hours to do a single run, the analytical model took only a few minutes. Both model and experimental results indicate that there was no reduction in infiltration rates or volumes infiltrated with intermittent as compared to continuous wetting. Thus the reduction in hydraulic gradient is not a factor in the reduced infiltration observed by others.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, October 2016. / The adsorption of molecules on a metal surface is core in heterogeneous catalysis. Surface sensitive techniques such as low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) are key tools to study adsorption geometries and structures of molecules and atoms on a metal surface. As our first model system we investigated the dissociation of NO on Ir{100}. The LEED experimental results showed a p(2 X 2) diffraction pattern at 300 K using. In this study two options were explored: phase mixing where dissociated nitrogen and oxygen are on the same unit cell, as well as phase separation where both nitrogen and oxygen form their own separate unit cell which results in a p(2 x 2) unit cell. Calculations were done on atop, bridge and hollow sites, with only perpendicular parameters and vibrational amplitude being varied initially. Results for phase mixing calculations gave the lowest R-factor of 0.70 ± 0.11 for atop site. We further considered phase separation for hollow and bridge sites for nitrogen and oxygen respectively because these two sites were found to be the most stable sites using DFT from previous studies. The lowest R-factors were 0.37 ± 0.06 for nitrogen c(2x2) and 0.24 ± 0.13 for oxygen p(2 X 1) For oxygen significant row pairing of iridium atoms stabilized the structure as mentioned in previous studies. Therefore from our results it is evident that phase separation models the experimental data better than phase mixing. Nitrogen and oxygen form c(2 X 2) and p(2 X 1) overlayer structures respectively which in combination result in a p(2 X 2) pattern that is in agreement with experimental results. The second system involves enantio-selectivity and chiral resolution at the organic-inorganic interfaces. The d-serine molecule was adsorbed on the Cu{110} surface. Density functional theory (DFT) calculations were used as a benchmark for our CLEED calculations. LEED experiments showed a (- 1 + 2: 40) overlayer pattern for d-serine adsorbed on Cu{110} surface. Three structures from DFT calculations with the lowest energy were used for CLEED calculations. These structures differed by the way they bond to the surface and molecular interactions. Calculations were carried out on these three structures and the structure with intra-dimer bonding was the best structure. The searches for this structure were further optimized by introducing pairing of the atoms in the row reconstruction on the copper surface and angle search. The lowest value obtained was 0.37 ± 0.09, which suggests that further understanding of this system is needed. The ultra-high vacuum (UHV) chamber was fully commissioned and is now ready for TPD and XPS studies. / LG2017

The influence of voids on the moisture uptake of epoxy has been studied. Specimens with void contents from 0 to about 50% were prepared. Void geometry and content were analyzed using microscopy and density methods. Void containing dry samples were characterized by Differential Scanning Calorimetry and Dynamic-Mechanical Analysis which verified consistency of chemistry of the epoxy network. The moisture uptake of specimens immersed in distilled water at 40 °C was monitored. The rate of absorption and saturation moisture content increased with increasing void content. The moisture uptake of void-free and void containing specimens was non-Fickian. The Langmuir model provided good fits to the experimental results for specimens with low to medium void content, although the moisture uptake of the high void content specimens showed substantial deviations from the Langmuir diffusion model. The moisture diffusivity agreed reasonably with predications from the Maxwell inclusion model over a range of void contents from 0 to 50%. The state of sorbed water was examined using mass balance calculations and DSC analysis. Only 6-8% of the void volume is occupied by water at saturation. Absorbed water may be classified as free and bound water. For void-free specimens, only bound water was found. The medium and high void content specimens contained water in three states: free water, freezable bound water, and non-freezable bound water. The DSC results show that the proportions of free water and freezable bound water increase with increasing void content, while the content of non-freezable bound water decreased. Moisture induced swelling decreased with increasing void content. The swelling is attributed to the content of non-freezable bound water. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Chitin is known as an effective biosorbent, which is used to preconcentrate PCP for further treatment. In order to reuse and recover the biosorbent, magnetic separation is a cost-effective alternative to separate the PCP-adsorbed biosorbent (i.e. chitin) from the treated water. Therefore, chitin is immobilized by magnetite prior PCP adsorption. From the immobilization results, the solution pH, temperature, agitation rate do not show great effect on the immobilization of chitin and magnetite. Second, magnetite-immobilized chitin can be formed as quickly as 5 min. Moreover, the interaction of chitin and magnetite is very strong since it is not easy to separate by vigorous shaking, high temperature and changing pH. Although the underlying mechanism of magnetite and chitin is still obscure, the biosorbent is proved to have high stability and reusability. In addition, both Langmuir and Freundlich models indicate that immobilization of chitin by magnetite is favorable with the Langmuir model being the major one. / For PCP adsorption study, it is found that magnetite-immobilized chitin can retain the PCP adsorption ability as free chitin. In accordance with the results, the PCP adsorption of magnetite-immobilized chitin is influenced by altering the parameters of biosorbent concentration, solution pH, temperature, agitation rate, contact time and initial PCP concentration. In general, higher amount of biosorbent gives higher removal efficiency (RE) but lower removal capacity (RC) as more binding sites are available for PCP. The PCP removal is enhanced by lowering pH since uncharged PCP is favorable for adsorption. It is speculated that hydrophobic interaction, hydrogen bonding and electrostatic interaction are involved. In addition, the biosorption efficiency is impeded by high temperature. Evidence shows that the adsorption might be due to the exothermic force such as hydrogen bonding. The biosorption is described as biphasic mechanism with the fast initial phase followed by slow equilibrium phase. For the PCP (10 mg/L) adsorption, the optimized conditions are: 1,500 mg/L of magnetite-immobilized chitin, initial pH 6, 25°C, 200 rpm and 60 min. The RE is 57.9% and RC is 5.4 mg/g. However, the increase in the amount of immobilized chitin (24,000 mg/L) can increase the RE up to 98%. By considering the Langmuir and Freundlich isotherms, the adsorption might be heterogenous, as the correlation coefficient from Freundlich model is higher. / Pentachlorophenol (PCP), a highly chlorinated aromatic organic compound, was widely used as a biocide and is now restrictly used as a wood preservative. PCP is toxic and ubiquitous environmental pollutant. In the present study, integrated treatment of biosorption and photocatalytic oxidation (PCO) using magnetite-immobilized chitin is employed to completely degrade PCP. / To thoroughly remove PCP, PCO is also employed after the biosorption. One hundred % of PCP removal is achieved after 5 h irradiation time, in 100 mL solution at initial pH 9 with 20 mM of H2O2 and 200 mg/L of TiO2. The intermediates of PCP are identified as 2,3,5,6-tetrachlorohydroquinone (TeHQ) and 2,3,5,6-tetrachlorophenol (TeCP) by GC/MS analysis. In addition, the toxicity of sample is monitored by the solid-phase and aqueous-phase Microtox RTM tests, which the toxicity increases and then decreases along the irradiation time. The biosorbent shows no great changes on chitin content and functional groups after PCO. In addition, the results imply that magnetite-immobilized chitin has a good potential to be reused at least for four cycles with high RE and DE. Therefore, the combination of biosorption and PCO treatment was feasible for PCP removal and the system is economic and convenient for repeated use. / by Pang, King Man. / "Oct 2007." / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4636. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 186-212). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries