In this study, the target compound is dimethyl sulfoxide (DMSO), which is used as a photoresist stripping solvent in the semiconductor and thin-film transistor liquid crystal display (TFT-LCD) manufacturing processes. The effects of the operating parameters (pH, Fe(2+) and H2O2 concentrations) on the degradation of DMSO in the fluidized-bed Fenton process were examined. This study used the Box-Behnken design (BBD) to investigate the optimum conditions of DMSO degradation. The highest DMSO removal was 98 % for pH 3, when the H2O2 to Fe(2+) molar ratio was 12. At pH 2 and 4, the highest DMSO removal was 82 %, when the H2O2 to Fe(2+) molar ratio was 6.5. The correlation of DMSO removal showed that the effect of the parameters on DMSO removal followed the order Fe(2+) > H2O2 > pH. From the BBD prediction, the optimum conditions were pH 3, 5 mM of Fe(2+), and 60 mM of H2O2. The difference between the experimental value (98 %) and the predicted value (96 %) was not significant. The removal efficiencies of DMSO, chemical oxygen demand (COD), total organic carbon (TOC), and iron in the fluidized-bed Fenton process were higher than those in the traditional Fenton process.
A B S T R A C TTriclosan is used as an antimicrobial in many processes. Fenton's reagents were used to degrade triclosan in combination with an electrochemical system, and the effects of operating parameters were investigated. The pH, current density, Fenton's reagents ratio, and H 2 O 2 feeding modes were investigated to determine their effect on the process efficiency. The results showed that higher efficiency could be achieved by increasing the H 2 O 2 concentration during Fenton's reagents ratio modification and by changing the H 2 O 2 feeding mode development from a one-time initial feeding mode to a step feeding mode of operation. This could also reduce the toxicity potential of the one-time initial feeding mode. Under optimum pH, Fenton's reagents ratio, and electrical current density conditions, 1 mM triclosan could be completely removed in the initial H 2 O 2 feeding operation. Additionally, the initial degradation rate for the first-order model and relative oxidation performance ratio was used to indicate process optimization. High performance liquid chromatography, ion chromatograph data, and gas chromatography-mass spectrophotometer confirmation results were used to identify the intermediates that comprised 2,4-dichlorophenol, 4-chloro-catechol, phenol, hydroquinone, p-benzoquinone, maleic, acetic, oxalic, and formic acids, that were present among the degradation reactions. The main oxidation intermediates present depended on the H 2 O 2 operating feeding mode.
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