Study on Fenton Degradation Efficiency for Metal Coating Wastewater
| Autor: | Chun-Hsiang Chang, 張竣翔 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 Most Fenton studies often aimed at the laboratory synthetic wastewaters owing to complex constituents in process wastewater. In this study, Fenton reaction was used to treat metal coating process wastewater from a precision machinery factory. GC/MS was used analyze the wastewater composition with the degradation rate, the amount of sludge, and degradation pathways for a comprehensive study. Four variables were included in the study, including Fe2+ concentration, H2O2 concentration, initial pH and temperature for Taguchi experiment with the targets of the degradation rate and the amount of sludge. The optimum degradation efficiency were achieved with the factors of pH 3.5, Fe2+ 10 mM, H2O2 0.5 M, temperature 55℃ to reach the COD removal rate 86.8%. Some interactions of factors were observed. The optimum factors for few sludge were pH 3.5, Fe2+ 1 mM, H2O2 10 M and temperature 55℃ with the sludge content 1.739 g/L. More experiments found that the optimum H2O2/Fe2+ ratio were 100 with COD removal rate of 87.3% and sludge of 4.127 g/L. The organic matter, Na2SO4, FeCO3, Na2Fe (SO4)2 of sludge were analysis by XRD. In order to explore the interactions of the factors, the first part of study included three variables of pH, Fe2+ and H2O2 in the response surface method with the degradation rate and the amount of sludge as the targets. When the reaction time was set at 1 hour, the reaction rate and degradation rate was fast for high Fe2+concentration (12 mM). At 6 hours, the concentration of H2O2 (1.1 M) was more important as the residual of H2O2 resulted in increasing the degradation efficiency. In the first hours, the degradation rate was better at pH 3 better and later for pH 3.5 as proton produced. The amount of sludge increased with the addition amount of Fe2+. As adjusting for low initial pH with NaOH, the sludge amount would increase as pH adjusted. The second part of study was to change organic contents in the metal coating process wastewater in order to optimize the Fenton dosage and to meet the effluent standards. As GC/MS analyzed the contents of the metal coating wastewater included six constituents of methyl isobutyl ketone, toluene, ethylbenzene, o-xylene, cyclohexanone and p-xylene. First, the degradation pathway involved the breakage of external C-C single bond of ethylbenzene, o-xylene, p-xylene toluene and benzene. Then, the further degradation would break the benzene ring to produce intermediate of dimethoxymethane. The following steps would be followed the order of molecular sizes, from cyclohexanone, methyl isobutyl ketone, methoxy ethylene to smaller molecules or even fully mineralized to carbon dioxides and water. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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