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10mg/L的2,4-D,48h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0.0043、0.0026和0.0032h-1.环境条件对降解效率有显著影响,2,4-D初始浓度在0～10mg/L、纳米Fe3O4投加量0～300mg/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.
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 Fe3 O4,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 Fe3 O4.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 Fe3 O4 conformed to pseudo-first-order kinetics,and the reaction rate constant（K） of 4-CP,2,4-DCP and phenol were 0.004 3 h-1,0.002 6 h-1 and 0.003 2 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 Fe3 O4 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.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2010年第6期1499-1505,共7页
Environmental Science
基金
国家自然科学基金项目(40971182)
国家高技术研究发展计划(863)项目(2006AA06Z356)
国家重点基础研究发展规划(973)项目(2007CB936604)
安徽省科技攻关项目(07010302212)
安徽省人才开发资金项目(2007Z014)
关键词
纳米FE3O4
2
4-D
脱氯降解
动力学
降解产物
nanoscale Fe3O4
2
4-dichlorophenoxyacetic acid
dechlorinated degradation
kinetics
degradation products
