Innovative Fenton/(mono)persulfate Oxidation Processes for the Degradation of Reactive Black B and Bisphenol A
| Autor: | Yi-Fong Huang, 黃毅峰 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 This study mainly proposed two novel technologies for efficient Bisphenol A (BPA) decontaminantion, and investigated the behavior of dominant radicals and intermediates involved in these BPA degradation processes. Firstly, we took advantage of the high oxidation–reduction potential of hydroxyl and sulfite radicals transformed from peroxymonosulfate (PMS) (stoichiometric ratio: [PMS]0/[BPA]0 = 2) as the oxidants to oxidize BPA to less complex intermediates. The expected radicals were used to mineralize those compounds very efficient (TOC removal ~40% at 1 h). Further, qualitative identification of both hydroxyl and (bi)sulfate radicals was performed to evaluate their dominance under different conditions. Secondly, a two–stage oxidation (UV–Na2S2O8/H2O2–Fe(II,III)) process was applied to mineralize BPA at pHi (initial pH) = 7 based on the concept for improving the common drawbacks of Fenton’s family (i.e. Fenton, Fered–Fenton and Photo–Fenton processes). We take advantage of the high oxidation potential of sulfate radicals and use persulfate (stoichiometric ratio: [S2O82–]0/[BPA]0 = 1) as the 1st–stage oxidant to oxidize BPA to less complex intermediates. Afterwards, photo–Fenton process was used to mineralize those intermediates to CO2 (TOC removal was increased 40% to 91%). To the best of our knowledge, this is the first attempt to utilize the two processes in conjunction for the complete degradation of BPA. This is also the first attempt to evidence that the dominant behavior of radicals in a (bi)sulfite process is very different from that in a persulfate process. Additionally, the utilization of extremely small amounts of activator and oxidant for the complete degradation of BPA was achieved. Moreover, both the BPA degradation in these two proposed oxidation processes formulated a pseudo–first–order kinetic model well as suggested as literature review. Differently, the much lower activation energy (ΔE = 26 kJ mol–1) was further calculated in the UV–Na2S2O8/H2O2–Fe(II,III) process to clarify that the thermal–effect of an illuminated system differs from single heat–assisted systems described. Final TOC removal levels of BPA by the use of such two–stage oxidation processes were 25–34%, 25%, and 87–91% for additional Fe(II,III) activation, H2O2 promotion, and Fe(II,III)/H2O2 promotions, respectively. For the Co2+/PMS oxidative process, the BPA degradation is not obviously dependent on the PMS concentration, but is related to Co2+ dosage over a practicable range of 25–45 °C. Possible BPA side–chain oxidative metabolic pathways are suggested based on experimental results incorporating the evidence from EPR (electron paramagnetic resonance) and analysis from GC–MS (gas chromatography–mass spectrometry). Hence, the experimental results are believed to be useful for further study. Furthermore, the proposed procedures with low chemical dosages have great potential for lowering operational costs, and thus can be practically implemented with other AOPs as a pretreatment of industrial biological processes. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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