摘要
为探讨水体中腐殖酸(humic acids,HAs)和铁元素对共存系统中环境污染物迁移转化的影响,利用红外光谱、紫外/可见吸收光谱和荧光光谱仪等手段表征了腐殖酸和Fe(Ⅲ)共存时的结构形态.结果表明,二者形成了稳定的络合物.电子顺磁共振图谱表明,腐殖酸、Fe(Ⅲ)以及HAs-Fe(Ⅲ)络合物在λ=355 nm光照下均能产生.OH.氙灯光照下(λ>290 nm),除草剂2,4-二氯苯氧乙酸(2,4-dichlorophenoxyacetic acid,2,4-D)的光降解遵循准一级动力学过程.单纯2,4-D(2 mg.L-1)溶液的降解速率常数为0.007 h-1,而含有HAs(5 mg.L-1)、Fe(Ⅲ)(0.2 mmol.L-1)及二者络合物的2,4-D溶液的降解速率常数分别是0.004、0.034和0.046 h-1.腐殖酸存在时,2,4-D的光降解速率受到了抑制;而Fe(Ⅲ)的存在加速了2,4-D的光降解;腐殖酸和Fe(Ⅲ)共存时,所形成的HAs-Fe(Ⅲ)络合物对2,4-D的光降解速率比单独的Fe(Ⅲ)存在时更快.
To elucidate the roles of humic acids （HAs） and iron on the environmental fate and transport of organic pollutants in natural water, the interactions of HAs with Fe（Ⅲ ） were characterized by Fourier transform infrared spectroscopy （FTIR） spectra, Ultravioletvisible （UV-vis） spectra and fluorescence spectra, indicating the formation of HAs-Fe（Ⅲ） complex. Electron paramagnetic resonance （EPR） spectra show · OH radicals are generated and can participate in the photoreaction in solutions containing HAs, Fe（ Ⅲ ） and HAs-Fe （ Ⅲ ） complex. Under Xe lamp irradiation （ A 〉 290 nm） , the photodegradation of 2,4-dichlorophenoxyaeetic acid （ 2,4-D）, as a kind of herbicide, followed the pseudo-first-order reaction kinetics. The pseudo-first-order rate constant of 2,4-D photodegradation with the presence of only2,4-D （2 mg· L^-1） was0.007 h^-1. In the presence of HAs （5 mg· L^-1）, Fe（Ⅲ） （0.2 mmol· L^-1） and HAs-Fe（ Ⅲ ） complex, the rate constants of 2,4-D degradation were 0. 004, 0. 034 and 0. 046 h^-1 , respectively. It was interesting to note that in the existence of HAs, 2,4-D photodegradation was inhibited. While in the presence of Fe（ Ⅲ ） , 2,4-D photodegradation was enhanced. Furthermore, in the coexistence of HAs and Fe（ Ⅲ ） , HAs-Fe（ Ⅲ ） complex showed better increased effect on the photodegradation of 2,4-D than Fe（ Ⅲ ） alone.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2010年第2期379-384,共6页
Environmental Science
基金
国家重点基础发展规划(973)项目(2006CB403302)
