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A platform for research: civil engineering, architecture and urbanism
An often-overestimated adverse effect of halides in heat/persulfate-based degradation of wastewater contaminants
Abstract Halides (X−) in the industrial wastewater are usually thought to adversely affect the degradation kinetics and mineralization rates in several SO4 −-based advanced oxidation processes. However, their unfavorable effects might be overestimated, particularly the heat/persulfate (PS) system as tested in the present study. Here the degradation of phenol, benzoic acid, coumarin and acid orange 7 (AO7) was examined with the presence of chloride or bromide in a heat/PS process. Cl− was found to have a dual effect (inhibition followed by enhancement) on the decomposition rates of organic pollutants, whereas the effects of Br− are insignificant within the tested concentration (0–0.2 mM). However, some chlorinated or brominated compounds were still identified in this heat/PS system. Unexpectedly, the mineralization rates of AO7, phenol, benzoic acid and coumarin were not apparently inhibited. In addition, the formation of adsorbable organic halogen (AOX) in the heat/PS system was much less than those in the peroxymonosulfate (PMS)/Cl− or PMS/Br− systems. According to the results of kinetic modeling, SO4 − was the dominating radical for AO7 degradation without Cl− or Br−, but Cl2 − was the main oxidant in the presence of Cl−, SO4 −, Br and Br2- were responsible for the oxidation of AO7 in the presence of Br−. The present study assumes that X2/HOX, rather than halogen radicals, is responsible for the enhanced formation of organohalogens. These findings are meaningful to evaluate the PS-based technologies for the high-salinity wastewater and to develop useful strategies for mitigating the negative effects of halides in advanced oxidation processes (AOPs).
Graphical abstract Display Omitted
Highlights Several chlorinated and one brominated byproducts were identified in heat/PS system. TOC removal was not inhibited with Cl− or Br− in heat/PS system. AOX formation with heat/PS was much less than PMS oxidation systems. Profiles and contributions of main radicals in heat/PS system were modelled.
An often-overestimated adverse effect of halides in heat/persulfate-based degradation of wastewater contaminants
Abstract Halides (X−) in the industrial wastewater are usually thought to adversely affect the degradation kinetics and mineralization rates in several SO4 −-based advanced oxidation processes. However, their unfavorable effects might be overestimated, particularly the heat/persulfate (PS) system as tested in the present study. Here the degradation of phenol, benzoic acid, coumarin and acid orange 7 (AO7) was examined with the presence of chloride or bromide in a heat/PS process. Cl− was found to have a dual effect (inhibition followed by enhancement) on the decomposition rates of organic pollutants, whereas the effects of Br− are insignificant within the tested concentration (0–0.2 mM). However, some chlorinated or brominated compounds were still identified in this heat/PS system. Unexpectedly, the mineralization rates of AO7, phenol, benzoic acid and coumarin were not apparently inhibited. In addition, the formation of adsorbable organic halogen (AOX) in the heat/PS system was much less than those in the peroxymonosulfate (PMS)/Cl− or PMS/Br− systems. According to the results of kinetic modeling, SO4 − was the dominating radical for AO7 degradation without Cl− or Br−, but Cl2 − was the main oxidant in the presence of Cl−, SO4 −, Br and Br2- were responsible for the oxidation of AO7 in the presence of Br−. The present study assumes that X2/HOX, rather than halogen radicals, is responsible for the enhanced formation of organohalogens. These findings are meaningful to evaluate the PS-based technologies for the high-salinity wastewater and to develop useful strategies for mitigating the negative effects of halides in advanced oxidation processes (AOPs).
Graphical abstract Display Omitted
Highlights Several chlorinated and one brominated byproducts were identified in heat/PS system. TOC removal was not inhibited with Cl− or Br− in heat/PS system. AOX formation with heat/PS was much less than PMS oxidation systems. Profiles and contributions of main radicals in heat/PS system were modelled.
An often-overestimated adverse effect of halides in heat/persulfate-based degradation of wastewater contaminants
Yang, Fei (author) / Sheng, Bo (author) / Wang, Zhaohui (author) / Yuan, Ruixia (author) / Xue, Ying (author) / Wang, Xiaoxiao (author) / Liu, Qingze (author) / Liu, Jianshe (author)
2019-06-10
Article (Journal)
Electronic Resource
English
Heat stress is overestimated in climate impact studies for irrigated agriculture
| DOAJ | 2017