State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China.
State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China.
Water Res. 2017 Nov 15;125:209-218. doi: 10.1016/j.watres.2017.08.049. Epub 2017 Aug 23.
In this study, the kinetics of reactions of peroxymonosulfate (PMS) with ten model phenols (including phenol, methylphenols, methoxyphenols, and dihydroxybenzenes) were examined. The oxidation kinetics of these phenols by PMS except for catechol and resorcinol showed autocatalysis in alkaline conditions (pH 8.5 and 10), due to the contribution of singlet oxygen (O) produced from PMS activation by quinone intermediates formed from their phenolic parents. The oxidation rates of ortho- and meta-substituted methylphenols and methoxyphenols by PMS were much higher than their para-substituted counterparts under similar conditions. This was attributed to the relatively low yields of quinone intermediates from para-substituted phenols. SMX could be efficiently degraded by PMS in the presence of phenols which showed great autocatalysis when they individually reacted with PMS, and the addition of methanol in excess had negligible influence suggesting that O rather than hydroxyl radical and sulfate radical played an important role. Transformation of SMX by O underwent three pathways including hydroxylation of aniline ring, oxidation of aromatic amine group to generate nitro-SMX, and oxidative coupling to generate azo-SMX and hydroxylated azo-SMX. These results obtained in this work improve the understanding of in situ chemical oxidation using PMS for remediation of subsurface, where phenolic and quinonoid moieties are ubiquitous.
在这项研究中，考察了过一硫酸盐 (PMS) 与十种模型酚类物质（包括苯酚、甲基苯酚、甲氧基苯酚和二羟基苯）反应的动力学。除邻苯二酚和间苯二酚外，PMS 对这些酚类物质的氧化动力学在碱性条件（pH 8.5 和 10）下表现出自催化作用，这归因于醌中间体形成的 PMS 活化产生的单线态氧 (O) 的贡献，这些醌中间体是由它们酚类母体形成的。在相似条件下，邻位和间位取代的甲基苯酚和甲氧基苯酚与 PMS 的氧化速率远高于对位取代的酚类物质。这归因于对位取代酚类物质生成的醌中间体产率相对较低。在酚类物质存在下，SMX 可以被 PMS 有效降解，当它们单独与 PMS 反应时表现出很大的自催化作用，过量添加甲醇几乎没有影响，这表明 O 而不是羟基自由基和硫酸根自由基发挥了重要作用。O 对 SMX 的转化经历了三种途径，包括苯胺环的羟化、芳香胺基团氧化生成硝基-SMX 以及氧化偶联生成偶氮-SMX 和羟基化偶氮-SMX。这些在这项工作中获得的结果提高了对使用 PMS 进行原位化学氧化修复地下水中酚类和醌类物质的理解，在地下水中酚类和醌类物质是普遍存在的。
