磷钨酸光催化降解直接大红4BE溶液的研究  

Photocatalytic degradation of azo-dye direct red 4BE aqueous solution catalyzed by phosphatotungstic acid

作　　者：魏红[1] 李克斌[2] 赵锋[2] 张涛[2] 李娟[1] 

机构地区：[1]西安理工大学西北水资源与环境生态教育部重点实验室,陕西西安710048 [2]西北大学化学与材料科学学院,合成与天然功能分子化学教育部重点实验室,陕西西安710069

出　　处：《中国环境科学》2011年第6期921-926,共6页China Environmental Science

基　　金：国家自然科学基金资助项目(51009115);陕西省教育厅科研专助项目(07JK349);陕西省科技计划项目(2010JQ5008)

摘　　要：以磷钨酸(PW12)为催化剂,对偶氮染料直接大红4BE进行均相光催化降解,考察了PW12用量、染料初始浓度对反应的影响,并对反应机理进行了探讨.结果表明,PW12能够有效光催化降解直接大红4BE.PW12用量≤600mg/L时,直接大红4BE的降解随PW12用量的增加明显加快,光解过程符合表观一级反应动力学.当pH2.0、直接大红4BE初始浓度为50mg/L、PW12用量为600mg/L时,其光催化降解效果最佳,对应的一级表观反应速率常数k为0.1164min-1.直接大红4BE初始浓度在50～150mg/L范围内,PW12对其光催化降解速率随染料浓度的增加而减小.结合直接大红4BE的循环伏安图,以及不同实验条件下PW12光催化直接大红4BE的UV-vis光谱图,进行的机理探讨结果表明,实验条件下,直接大红4BE的PW12光催化脱色过程是?OH氧化,PW12*–直接大红4BE复合物内的电子转移,以及杂多蓝PW12(e-)还原共同作用的结果,其中?OH氧化脱色起主导地位.The photodegradation of azo-dye direct red 4BE（4BE） in aqueous solution by phosphatotungstic acid（PW12） as homogeneous catalyst was studied in a batch photoreactor.The parameters such as the concentration of 4BE and PW12were investigated,and the reaction mechanism involved was discussed.4BE was decolorized effectively in the presence of phosphatotungstic acid under UV irradiation.When PW12 concentration was less than 600mg/L,the photocatalytic decolonization rate of 4BE increased along with the increase of PW12 concentration.The process of 4BE degradation followed a pseudo-first-order kinetics,and a maximum rate constant k of 0.1164min-1could be obtained at pH 2.0,PW12concentration of 600mg/L and 4BE initial concentration of 50mg/L.The photocatalytic degradation rate of 4BE decreased with the increase of dye concentration when 4BE concentration was in the range of 50 to 150mg/L.On the basis of the results of cyclic voltammogram and the UV-vis spectrum of 4BE,the mechanism for the photodegradation of 4BE by phosphatotungstic acid includes three pathways： oxidation by hydroxyl radicals,electron transfer within the complex of the excited phosphatotungstic acid and 4BE,and reduction of dye by the reduced phosphatotungstic acid,in which the oxidation of hydroxyl radicals palys a leading role.

关 键 词：磷钨酸 均相光催化 直接大红4BE 反应机理 

分 类 号：X132[环境科学与工程—环境科学]