| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程所 === 93 === Applying Fenton / Fluidized Crystallization process to remove chlorophenol and Fe(III)
Student: Chih-Huan Chien Advisor: Dr. Chung-Hsuang Hung
Department of Safety, Health, and Environmental Engineering
National Kaohsiung First University of Science and Technology
ABSTRACT
The aim of this study is to develop a Fenton oxidation/fluidization crystallization process to remove chlorinated phenols from wastewater and to reduce the formation of iron-containing sludge. 2,4-dichlorinephenol (2,4-DCP) is selected as the investigated target compound in the study. Series of tests, which involve the major experimental parameters including solution pH level, H2O2 concentrations and its dosage ways, and iron concentrations, are conducted for process development.
The experimental results indicate that the initial degradation rates of 2,4-DCP followed first-order reaction kinetics in the Fenton reactions and the degradation rates increase with both concentrations of H2O2 and Fe+2. Based upon our observation, the side reactions could be ceased by “multi-step input” of H2O2 instead of dumping all H2O2 to the reaction at one time. Besides, this study also demonstrates that wasted iron shavings can be applied as a substituted iron source for the Fenton reaction. Fe+2 can be released from iron shavings in pH= 3 solution. The releasing rates of Fe+2 from the iron shavings are so gentle and continuous that the side reactions for Fenton reactions or the Fention-like reaction will not happen and a continuing decomposition of 2,4-DCP is observed. It seems that the wasted iron shavings can be a better iron source.
In comparison of the decomposition ratios of 2,4-DCP among the tested reaction systems, the ratios are in the order of fluidized bed iron shavings Fenton > fluidized bed Fenton > iron shavings Fenton > traditional Fenton. More than 80% of decomposition of 2,4-DCP is detected in these reactions within 30-minute reaction period. Due to less side reactions taking place, the fluidized bed iron shavings Fenton reaction system achieves higher decomposition ratio of 2,4-DCP. In addition, better mass transfer being achieved in the fluidized reaction systems may also result in higher degradation rate of 2,4-DCP in fluidized bed reactors.
For the removal of iron from solution by the fluidization crystallization process, a lowest removal ratio of 40% of released iron which precipitates on sands is detected. But, the precipitated iron may dissolve as the reactions proceed. Fortunately, the re-dissolved iron will reach a concentration as high as the equilibrium concentration. More investigation is undergoing to reduce the re-dissolution phenomena of precipitated iron.
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