Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Chemical and Biochemical Engineering." Includes bibliographical references (p. 134-141).

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 255-268). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Rousseau, Ronald; Committee Member: Meredith, Carson; Committee Member: Prausnitz, Mark; Committee Member: Teja, Amyn; Committee Member: Wilkinson, Angus. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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The aim of this study was to determine in an empirical manner whether the phenomenon of hearing loss due to the exposure to volatile organic solvents was present in the gasification plants of a petrochemical factory. The experimental groups included unexposed (N=20) workers, workers (N=20) exposed to noise and workers (N=19) exposed to noise and volatile organic solvents. The following assessments were made: diagnostic audiometry for the assessment of hearing thresholds; biological monitoring of ortho-cresol and hippuric acid for the biological markers of toluene; passive air sampling and noise measurements. Questionnaires were completed by the three groups to collect information about age, ethnicity, smoking habits, alcohol consumption and work history regarding the exposure to ototoxic substances as well as the period of employment. There were no statistically significant differences between the average ages of the three groups, but more of the workers in the noise group were from a higher age group. This age composition and the work history of the noise group were considered as possible influences on the results of this hearing study. The results of the passive air sampling show that the levels of volatile organic solvents were lower than the occupational exposure limits on the day of sampling. The biological monitoring shows that the markers, namely hippuric acid and o-cresol, were lower than the biological exposure indices. The noise group was exposed to sound pressure levels of 79-90 dB(A) and the noise + hydrocarbon group to levels of 85-88 dB(A). The average hearing thresholds of the noise group were at most of the frequencies (0.5-8 kHz) significantly higher (p≤0,05) than that of the noise + hydrocarbon group. The average hearing thresholds of the control group were overall lower than the noise group's hearing thresholds, but on average a little higher than the noise + hydrocarbon group's hearing thresholds. No relationship was found in this study between the exposure to volatile organic solvents (for example toluene that was used as marker in this study) and the elevation of hearing thresholds of workers at the gasification plants of the petrochemical factory. / Thesis (M.Sc.)--North-West University, Potchefstroom Campus, 2004.

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The aim of this study was to assess the performance of thermal heating for the removal of chlorinated solvents from fractured rock. The study included a laboratory experimental program, a field pilot study demonstration and a mathematical modeling component. In the laboratory experimental program, thermal heating parameters, such as operational temperature, heating duration, and the corresponding degree of contaminant removal, were evaluated through a series of heating tests. To evaluate the effect of heating temperature and heating duration on the degree of contaminant mass removal, two different heating profiles were utilized during the experiments. Additionally, seven types of rock and two common contaminants were selected to evaluate the effect of thermal heating on different geological media impacted with different chlorinated compounds. In general, results showed that heating duration had the most significant effect on the degree of contaminant mass removal in post-remedy samples. Results showed that a higher porosity in combination with a lower organic content facilitates the removal of chlorinated solvents from the rock matrix. A Thermal Conductive Heating (TCH) pilot test was implemented by TerraTherm, Inc. at the former Naval Air Warfare Center (NAWC) in West Trenton, NJ to assess the performance of TCH for the removal of trichloroethylene (TCE) and daughter products (i.e cis-1,2-dichloroethylene (DCE) and vinyl chloride (VC)) from fractured bedrock. Results showed that treatment removed 318.5 kg of TCE, DCE and VC, from the treatment zone, of which 62.6 kg were recovered from the rock matrix. A total of 63 % TCE, 65.8 % of DCE and 90.4% of VC were removed during heating. Finally, Semi-analytical solutions were derived to evaluate back diffusion in a fractured bedrock environment where the initial condition comprises a spatially uniform, non-zero matrix concentration throughout the domain. It was concluded that the time required to reach a desired fracture pore water concentration is a function of the distance between the point of compliance and the upgradient face of the domain where clean groundwater is inflowing. Hence, shorter distances correspond to reduced times required to reach compliance. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-09-24 11:30:16.52

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The biocatalysis of a crude chlorophyllase extract, obtained from the biomass culture of Phaeodactylum tricornutum, in neat organic solvent media was investigated. The addition of selected excipients, including crown ether (enzyme:crown ether, 135:1--2.7:1, w/w), dextran (enzyme:dextran, 1:2--1:0.25, w/w), Span 40 and Span 60 (enzyme:Span, 1:2, w/w) and sodium bis (2-ethylhexyl) sulfosuccinate (enzyme:AOT, 1:12.6, w/w), to the crude solid enzyme preparation decreased the chlorophyllase activity. The effects of selected parameters, including solvent hydrophobicity (Log P, 2.40--4.45), initial water activity (aw, 0.44--0.97), agitation speed (0--200 rpm), reaction temperature (25--45°C) and enzyme concentration (1.67--5.3 mg solid enzyme/mL) on chlorophyllase activity, were investigated using a crude solid enzyme. The experimental findings showed that the highest chlorophyllase specific activity of 362.4 nmol hydrolyzed chlorophyll/g solid enzyme/min and bioconversion yield of 90.7% were obtained with the hexane/octanone mixture (98.7:1.3, v/v), aw of 0.90, agitation speed of 200 rpm, reaction temperature of 35°C and enzyme concentration of 3.33 mg solid enzyme/mL.