K_6Nb_(10.8)O_(30)对微囊藻毒素的光催化降解研究  

Photocatalytic Degradation of Microcystin-LR by K_6Nb_(10.8)O_(30)

作　　者：邹曦[1] 张高科[2] 胡艳君 潘晓洁[1] 万成炎[1] 邹怡[1] 张曼[1] 

机构地区：[1]水利部中国科学院水工程生态研究所水利部水工程生态效应与生态修复重点实验室,武汉430079 [2]武汉理工大学资源与环境工程学院,武汉400070 [3]广西柳州钢铁(集团)公司技术中心,柳州545002

出　　处：《水生态学杂志》2015年第5期8-14,共7页Journal of Hydroecology

基　　金：国家自然科学基金项目(51209147)

摘　　要：通过合成含铌类复合氧化物光催化剂,研究其光催化降解微囊藻毒素效率和作用机理,为去除水体中微囊藻毒素提供高效环保的水处理技术。采用溶胶凝胶法制备了铌酸盐光催化剂K_6Nb_(10.8)O_(30),利用X射线衍射、扫面电镜、紫外可见漫反射光谱等对光催化剂进行了结构表征,该化合物结构是属于四方相钨青铜结构,空间群为P4/mbm(127),晶粒呈长方柱性,直径约为150 nm,长度400~600 nm,吸收能带为2.92 e V;在紫外光(UVA)辐照条件下,考察了催化剂对微囊藻毒素(MC-LR)的光催化降解效果,利用高效液相色谱测定水体中微囊藻毒素浓度。结果表明,光催化剂K_6Nb_(10.8)O_(30)能够有效的降解藻毒素,降解过程受到pH值、藻毒素的初始浓度、催化剂投加量和光照的影响;在光辐射强度为556μW/cm^2、pH值4.24、催化剂投加量为0.375 g/L的试验条件下,初始浓度3 mg/L的藻毒素在180 min之内降解率达到93%;对催化剂反应前后的红外光谱分析表明,藻毒素的降解最终不是被催化剂吸附,而是被光催化降解;动力学研究表明,微囊藻毒素的光催化剂降解反应符合一级反应动力学规律,随着微囊藻毒素初始浓度的增大,反应速率常数逐步降低,半衰期也逐渐变长。Microcystins,produced during cyanobacteria blooms in eutrophic freshwater,possess high hepatotoxici-ty,can damage the nervous system and pose a significant health hazard to humans through drinking water.Micro-cystins have a cyclic heptapeptide structure that makes them highly stable and not easily decomposed by traditional treatment processes.As a result,many significant studies have carried out to find efficient methods for degrading microcystins.Fenton oxidation and photocatalytic oxidation are recognized as the most promising advanced technolo-gies for removal of microcystins at high efficiency,without producing toxic by-products,and have attracted much at-tention.MC-LR is one of the MCs more frequently observed and is listed in the Sanitary Standard for Drinking Wa-ter （2001）and Environmental Quality Standards for Surface Water （GB3838-2002）in China.In this study,pho-tocatalytic degradation of microcystin-LR was investigated using a new photocatalyst （K6 Nb10.8 O30 ）under low inten-sity UVA irradiation.The effects of K6 Nb10.8 O30 dosage,initial concentration of MC-LR and pH on the degradation efficiency of MC-LR were investigated and the photocatalytic properties and mechanism of the new photocatalyst were revealed by kinetic analysis.Furthermore,the experiments were conducted under UVA irradiation only or u-sing photocatalyst （K6 Nb10.8 O30 ）only as controls with each experiment carried out in triplicate.K6 Nb10.8 O30 was synthesized using niobium pentoxide by the sol-gel method and characterized by X-ray diffraction,scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy.Results indicate that K6 Nb10.8 O30 assumes a tetragonal tungsten bronze structure with space group P4 /mbm （127）.The particles display a tetragonal columnar shape of diameter 50 -150 nm and length 250 -400 nm.The band gap of K6 Nb10.8 O30 powders was estimated to be 2.92 eV.The concentration of MC-LR was detected by high performance liquid chromatography （HPLC）and re-sults show that MC-LR was easil

关 键 词：光催化 微囊藻毒素 降解 K6 Nb10.8 O30 

分 类 号：Q142[生物学—生态学]