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2 results on '"Dyi-Hwa Tseng"'

1. Effect of Oxygen and Hydrogen Peroxide on the Photocatalytic Degradation of Monochlorobenzene in Aqueous Suspension

Author

Dyi-Hwa Tseng, Lain-Chuen Juang, and Hsin-Hsu Huang

Subjects
Renewable energy sources, TJ807-830
Abstract

The influences of oxygen and hydrogen peroxide () on the degradation and mineralization of monochlorobenzene (MCB) during UV/ process were investigated. Experimental results indicated that oxygen was a determining parameter for promoting the photocatalytic degradation. The presence of oxygen reduced the illumination time needed for the complete decay of MCB from 240 to 120 min. The photocatalytic degradation of MCB in UV// photocatalysis followed a simplified two-step consecutive kinetics. The rate constants of degradation () and mineralization () were increased from 0.016 to 0.046 min−1 and from 0.001 to 0.006 min−1, respectively, as the initial concentration of dissolved oxygen (DO) was increased from 1.6 to 28.3 mg L−1. Owing to the fact that acted as an electron and hydroxyl radicals () scavenger, the addition of should in a proper dosage range to enhance the degradation and mineralization of MCB. The optimal dosage for MCB degradation was 22.5 mg L−1, whereas the most efficient dosage for MCB mineralization was 45.0 mg L−1. In order to minimize the adverse effects of higher dosage, including the capture of radicals and competitive adsorption, and to improve the photocatalytic degradation of MCB, the sequential replenishment of was suggested. For the stepwise addition of a total dosage of 45.0 mg L−1, a complete destruction of MCB was observed within 120 min of irradiation. Additionally, the mineralization efficiency was about 87.4% after 240 min of illumination time.

Published
2012
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2. A trickling fibrous-bed bioreactor for biofiltration of benzene in air

Author

Qi Zhou, Dyi-Hwa Tseng, Hojae Shim, Shang-Tian Yang, and Yu Liang Huang

Subjects
chemistry.chemical_classification, Pressure drop, Chromatography, Renewable Energy, Sustainability and the Environment, General Chemical Engineering, Trickling filter, Organic Chemistry, Analytical chemistry, Pollution, Volumetric flow rate, Inorganic Chemistry, Chemical kinetics, chemistry.chemical_compound, Fuel Technology, chemistry, Biofilter, Bioreactor, Volatile organic compound, Benzene, Waste Management and Disposal, Biotechnology
Abstract

A novel trickling fibrous-bed bioreactor was developed for biofiltration to remove pollutants present in contaminated air. Air containing benzene as the sole carbon source was effectively treated with a coculture of Pseudomonas putida and Pseudomonas fluorescens immobilized in the trickling biofilter, which was wetted with a liquid medium containing only inorganic mineral salts. When the inlet benzene concentration (C gi ) was 0.37 g/m 3 , the benzene removal efficiency in the biofilter was greater than 90% at an empty bed retention time (EBRT) of 8 min or a superficial air flow rate of 1.8 m 3 /m 2 .h. In general, the removal efficiency decreased but the elimination capacity of the biofilter increased with increasing the inlet benzene concentration and the air (feed) flow rate. It was also found that the removal efficiency decreased but the elimination capacity increased with an increase in the loading capacity, which is equal to the inlet concentration divided by EBRT. The maximum elimination capacity achieved in this study was ∼11.5 g/m 3 .h when the inlet benzene concentration was 1.7 g/m 3 and the superficial air flow rate was 3.62 m 3 /m 2 .h. A simple mathematical model based on the first-order reaction kinetics was developed to simulate the biofiltration performance. The apparent first order parameter K 1 in this model was found to be linearly related to the inlet benzene concentration (K 1 =4.64-1.38 C gi ). The model can be used to predict the benzene removal efficiency and elimination capacity of the biofilter for benzene loading capacity up to ∼30 g/m 3 .h. Using this model, the maximum elimination capacity for the biofilter was estimated to be 12.3 g/m 3 .h, and the critical loading capacity was found to be 14 g/m 3 .h. The biofilter had a fast response to process condition changes and was stable for long-term operation; no degeneration or clogging of the biofilter was encountered during the 3-month period studied. The biofilter also had a relatively low pressure drop of 750 Pa/m at a high superficial air flow rate of 7.21 m 3 /m 2 .h, indicating a good potential for further scale up for industrial applications.

Published
1998

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