Co^2+ 活化过氧单磺酸盐降解三氯生的条件优化及机理探讨

Conditions optimization and mechanism exploration of triclosan degradation in Co^2+ activated peroxymonosulfate oxidation process

采用Co^2+活化过氧单磺酸盐(PMS)降解水体中三氯生(TCS),优化了PMS浓度、溶液初始pH和Co^2+浓度等降解条件,并对TCS降解机理进行了探讨。结果表明,在溶液初始pH=7,PMS和Co^2+摩尔浓度分别为1.00 mmol/L和10.0μmol/L的优化条件下,TCS(34.5μmol/L)在30 min内去除率可达99.4%。虽然降解过程中会有优先控制有毒污染物2,4-二氯酚(2,4-DCP)的产生与累积,但是反应延长至120 min后2,4-DCP可降至0.38μmol/L,低于《美国推荐水质质量基准2002》(EPA-822-R-02-047)限值0.47μmol/L。因此,Co^2+/PMS体系不仅能实现TCS的有效降解,而且能抑制有毒中间产物2,4-DCP的累积。TCS在硫酸根自由基(SO4^-·)攻击下的主要中间产物为2,4-DCP、4-氯-邻苯二酚和羟基化TCS等,羟基化TCS在·OH参与下可进一步氧化产生醌类中间体,所有中间产物最终可以开环、矿化为有机酸、CO 2、H 2O和氯离子。

Triclosan(TCS)was degraded by aqueous Co^2+activated peroxymonosulfate(PMS)oxidation process.The conditions like PMS concentration,solution initial pH and Co^2+concentration were optimized.At last,mechanism of TCS degradation was explored.Results showed that solution initial pH=7,PMS molar concentration of 1.00 mmol/L and Co^2+molar concentration of 10.0μmol/L were optimized conditions,result in 99.4%removal rate of TCS(34.5μmol/L)within 30 min.During the degradation,priority pollutants 2,4-dichlorophenol(2,4-DCP)was formed and accumulated.However,if the degradation lasted for more than 120 min,2,4-DCP would decrease to 0.38μmol/L,below 0.47μmol/L which was regulated by“National recommended water quality criteria:2002”(EPA-822-R-02-047)of America.Therefore,the Co^2+/PMS system could not only realize the degradation of TCS,but also inhibit the accumulation of toxic intermediate 2,4-DCP.The major intermediates included 2,4-DCP,4-chlorocatechol,and hydroxylated TCS under SO4^-·attack.Hydroxylated TCS was further degraded to quinones intermediates with·OH participation.All the intermediates rings were finally broken and mineralized to organic acid,CO2,H2O and Cl^-.