【摘要】 为研究过量硫代硫酸钠与ClO2的反应动力学及其机理,采用停流技术测定该反应过程中各物质的浓度变化.结果表明,该化学反应方程式为:3S2O32-+2ClO2+H2O→S4O62-+2SO42-+2Cl-+2H+,建立相应的反应动力学方程,该反应对于ClO2和硫代硫酸钠均为一级,对S4O62-为0.5级,获取pH=9.27、T=298K和[S2O32-]0/[ClO2]0浓度范围为1.2～3.7情况下该反应的速率常数k值为2.8251×105L1.5/(mol1.5.s),反应活化能Ea为20.5kJ/mol,表明在一般的水处理研究中,硫代硫酸钠作为ClO2的猝灭剂是合理的,提出过量硫代硫酸钠与ClO2的4步反应机理,指出S2O3ClO22-是反应中重要的中间体,说明该反应遵循单电子转移机理.更多还原

【Abstract】 Kinetics and mechanism of the reaction between excess thiosulfate and ClO2were studied by following the concentration change of reactive substances with the stopped-flow technique. Results showed that the stoichemistry was found to be 3S2O32-+2ClO2+H2O→S4O62-+2SO42-+2Cl-+2H+. The equation of reaction kinetics was established. The reaction was first-order with respect to both ClO2 and thiosulfate,and half-order to tetrathionate. When pH was 9.27,water temperature was 298 K and ratio of [S2O32-]0/[ClO2]0 ranged from 1.2 to 3.7,the order reaction rate constant k was 2.8251×105 L1.5/(mol1.5·s),and the reaction activation energy was 20.5 kJ/mol,which reveals that taking thiosulfate as the fast terminating reagent of ClO2 is reasonable under usual water treatment conditions. A 4-step mechanism based on the theory of single electron transfer(SET) between excess thiosulfate and ClO2 is proposed,in which S2O3ClO22-plays a significant role.更多还原