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纳米四氧化三铁对2,4-D的脱氯降解
引用本文:方国东,司友斌.纳米四氧化三铁对2,4-D的脱氯降解[J].环境科学,2010,31(6):1499-1505.
作者姓名:方国东  司友斌
作者单位:安徽农业大学资源与环境学院,合肥,230036
基金项目:国家自然科学基金项目,国家高技术研究发展计划(863)项目,国家重点基础研究发展规划(973)项目,安徽省科技攻关项目,安徽省人才开发资金项目 
摘    要:采用纳米四氧化三铁(Fe3O4)降解水溶液中的2,4-二氯苯氧乙酸(2,4-D),考察了2,4-D初始浓度、纳米Fe3O4投加量、溶液pH和温度等因素对2,4-D降解率的影响.结果表明,纳米Fe3O4对2,4-D有显著的降解效果,初始浓度为10 mg/L的2,4-D, 48 h内降解率可达48%.纳米Fe3O4对2,4-D的降解是一个还原脱氯过程,反应体系中氯离子浓度随2,4-D浓度降低而升高.LC/MS分析表明,2,4-D降解的主要产物是苯酚,其他中间产物是2,4-二氯苯酚(2,4-DCP)、4-氯苯酚(4-CP)和2-氯苯酚(2-CP).溶液中2,4-D的降解符合准一级反应动力学,产物4-CP、2,4-DCP和苯酚的反应速率常数K分别为0.0043、0.0026和0.0032 h -1.环境条件对降解效率有显著影响,2,4-D初始浓度在0~10 mg/L、纳米Fe3O4投加量0~300 mg/L的范围内,2,4-D降解率随初始浓度和纳米Fe3O4投加量的增加而增大;pH对2,4-D的脱氯降解有显著影响,在pH为3.0时,纳米Fe3O4对2,4-D的还原脱氯效果最好;温度升高,可以提高脱氯反应速率.

关 键 词:纳米Fe3O4  脱氯降解  动力学  降解产物
收稿时间:2009/7/29 0:00:00
修稿时间:2009/12/4 0:00:00

Dechlorination Degradation of 2,4-D by Nanoscale Fe3O4
FANG Guo-dong and SI You-bin.Dechlorination Degradation of 2,4-D by Nanoscale Fe3O4[J].Chinese Journal of Environmental Science,2010,31(6):1499-1505.
Authors:FANG Guo-dong and SI You-bin
Abstract:Reductive transformation of 2,4-Dichlorophenoxyacetic acid (2,4-D) by nanoscale Fe3O4 was studied, and the effects of 2,4-D initial concentration, the dosage of nanoscale Fe3O4, pH and temperature on degradation rate of 2,4-D were investigated. The results showed that 48% 2,4-D with initial concentration of 10 mg/L was transformed within 48 h in the presence of 300 mg/L nanoscale Fe3O4. The degradation of 2,4-D was a reductive dechlorination process, and the concentration of chloride ion increased sharply with the degration of the 2,4-D. Disappearance of parent species and formation of reaction intermediates and products were analyzed by LC/MS. The transformation of 2,4-D followed a primary pathway of its complete reduction to phenol and a secondary pathway of sequential reductive hydrogenolysis to 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP) or 2-chlorophenol (2-CP) and phenol. The degradation equations of 2,4-D by nanoscale Fe3O4 conformed to pseudo-first-order kinetics, and the reaction rate constant (K) of 4-CP, 2,4-DCP and phenol were 0.0043 h-1, 0.0026 h-1 and 0.0032 h-1, respectively. The degradation rate increased with an increase in initial concentration of 2,4-D from 0 mg/L to 10 mg/L, and increasing the dosage of nanoscale Fe3O4 from 0 mg/L to 300 mg/L. The pH of reaction solution significantly influenced reductive degradation of 2,4-D, and the optimum pH value was 3.0. Besides, high temperature could improve dechlorination rate of 2,4-D.
Keywords:2  4-D
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