Peracetic Acid Oxidation of Saline Waters in the Absence and Presence of H2O2: Secondary Oxidant and Disinfection Byproduct Formation

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• 作者：Amisha D. Shah ; Zheng-Qian Liu ; Elisabeth Salhi ; Thomas H枚fer ; Urs von Gunten
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：February 3, 2015
• 年：2015
• 卷：49
• 期：3
• 页码：1698-1705
• 全文大小：359K
• ISSN：1520-5851

文摘

Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown. In this study, the reactivity of PAA with halide ions (chloride and bromide) to form secondary oxidants (HOCl, HOBr) was investigated. For the PAA鈥揷hloride and PAA鈥揵romide reactions, second-order rate constants of (1.47 卤 0.58) 脳 10^鈥? and 0.24 卤 0.02 M^鈥? s^鈥? were determined for the formation of HOCl or HOBr, respectively. Hydrogen peroxide (H₂O₂), which is always present in PAA solutions, reduced HOCl or HOBr to chloride or bromide, respectively. As a consequence, in PAA-treated solutions with [H₂O₂] > [PAA], the HOBr (HOCl) steady-state concentrations were low with a limited formation of brominated (chlorinated) disinfection byproducts (DBPs). HOI (formed from the PAA鈥搃odide reaction) affected this process because it can react with H₂O₂ back to iodide. H₂O₂ is thus consumed in a catalytic cycle and leads to less efficient HOBr scavenging at even low iodide concentrations (<1 渭M). In PAA-treated solutions with [H₂O₂] < [PAA] and high bromide levels, mostly brominated DBPs are formed. In synthetic water, bromate was formed from the oxidation of bromide. In natural brackish waters, bromoform (CHBr₃), bromoacetic acid (MBAA), dibromoacetic acid (DBAA), and tribromoacetic acid (TBAA) formed at up to 260, 106, 230, and 89 渭g/L, respectively for doses of 2 mM (ca. 150 mg/L) PAA and [H₂O₂] < [PAA]. The same brackish waters, treated with PAA with [H₂O₂] 鈮?[PAA], similar to conditions found in commercial PAA solutions, resulted in no trihalomethanes and only low haloacetic acid concentrations.