Biological processes have been proven to be economical and effective for control of volatile organic compounds (VOCs) with concentration of <1,000 mg C/m3 and VOCs such as toluene, xylenes, and dichloromethane(DCM) have been shown to be biodegradable. An activated sludge tank can be used as a bioscrubber for the purpose. Into the tank, an air stream is introduced through the spargers originally for aeration. Water-soluble contaminants in the air stream are absorbed into the mixed liquid and, subsequently, degraded by the microorganisms in the aeration tank. In this study, a pilot-scale activated-sludge tank (0.4 m¡Ñ0.4 m in cross-sectional area and 3 m in water depth) was used as a bioscrubber to study the treatability of gas-borne toluene, xylenes, and DCM. Synthetic gases with the three VOCs with concentrations in the rang of 250-1000 ppm (measured as methane) were used as the test gases. Effects of volumetric aeration rate (Q/V), influent VOC concentration, and submerged liquid depth on the removal efficiency of the influent VOCs were tested. Results show that with Q/V = 3.75-11.25 m3/m2.h, pH = 6-8, MLSS (mixed liquor suspended soilds concentration) = 1600-2800 mg/L, and submerged liquid depth D = 1.1 m, removal efficiencies were 93.1, 93.9, and 98.8%, respectively, for toluene, xylenes, and DCM. The removal efficiencies were nearly independent of the operating conditions.

No description available.

No description available.

Alumina supported manganese oxides were used in the gas phase oxidation of toluene by ozone. Catalyst activity and characterization, the promotional effect of noble metals (Pt and Pd) on the activity of manganese oxides, and the kinetics and mechanism of the reaction were investigated in this PhD thesis. It was shown that MnO2 and Mn2O3 were the active sites of the catalyst capable of oxidizing toluene to CO and CO2 below 100 oC. Catalysts were deactivated at room temperature due to the accumulation of carbonaceous species on their surface. At least 65 oC was required for the stable operation of the catalysts. X-ray absorption spectroscopy was used to study the structure and electronic properties of the mono metallic and bimetallic catalysts. It was found that the catalysts with higher Mn loading resulted in higher oxidation states of Mn which were less favorable for the oxidation of toluene. The addition of Pt to the Mn containing catalyst increased the reaction rate by transferring electrons from Pt to Mn. On the other hand, no promotional effect was observed by the addition of Pd to Mn. The Oxidation state of Mn atoms was one of the most important parameters, controlling the rate of toluene oxidation. Lower oxidation states of Mn were able to easily transfer electrons to ozone, accelerating the rate of toluene oxidation. A reaction mechanism was proposed for the catalytic oxidation of toluene over manganese oxides. In this mechanism, the oxidation of toluene was carried out by the abstraction of hydrogen atoms followed by the oxidation of toluene carbon skeleton. A rate equation was derived based on this mechanism, determining the reaction orders of -1 and 2 for toluene and ozone, respectively. It was concluded that catalytic ozonation is an effective method for the low temperature oxidation of volatile organic compounds (VOCs) in air. The significance of this method is related to energy saving in air purifying systems by reducing the required temperature to oxidize VOCs. Catalytic ozonation can be used in indoor and outdoor applications for removal of VOCs from enclosed environments or polluted industrial streams.

Graduate / 0485

Graduate / 0485

Thesis (M.S.)--Ohio University, June, 1984. / Title from PDF t.p.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 80-85). Also available via the Internet.

Thesis (Ph. D.)--University of Chicago, 1938. / Lithoprinted. "Private edition, distributed by the University of Chicago libraries, Chicago, Illinois." Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1926. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.