巯基改性高岭土负载CeO_2-CdS光催化降解结晶紫  

Photocatalytic Degradation of Crystal Violet by Modified Sulfydryl Kaolin Coated CeO_2-CdS

作　　者：徐杰[1] 郑建东[1] 张丽惠[1] 王金玉 张华[1] 马红梅 XU Jie;ZHENG Jiandong;ZHANG Lihui;WANG Jinyu;ZHANG Hua;MA Hongmei(College of Material Science and Chemical Engineering,Chuzhou University,Chuzhou 239000,China)

机构地区：[1]滁州学院材料与化学工程学院,安徽滁州239000

出　　处：《环境科学研究》2018年第6期1144-1151,共8页Research of Environmental Sciences

基　　金：安徽省质量工程项目(No.2015sjjd024;2015jxt040);滁州学院规划项目(No.2016GH13)~~

摘　　要：为获得高效催化活性的光催化材料,实现偶氮类染料的高效降解,试验以巯基乙酸钠作为硫源和高岭土改性剂合成了巯基高岭土/CeO_2-CdS催化剂,并以降解结晶紫为模板反应,优化确定了巯基高岭土/CeO_2-CdS催化剂的制备条件.采用XRD(X射线衍射)、SEM(扫描电子显微镜)、TEM(透射电子显微镜)、FTIR(傅里叶红外光谱)和UV-Vis(紫外-可见光漫反射光谱)对催化剂进行了表征.结果表明:(1)催化剂是由巯基高岭土、立方相结构的CdS和萤石结构的CeO_2组成;(2)CdS和CeO_2的负载破坏了巯基高岭土的层状结构;(3)最优催化剂和巯基高岭土/CeO_2的可见光的响应范围分别为550和450 nm;(4)当CeO_2∶CdS(摩尔比,下同)为4∶6,巯基高岭土∶CeO_2-CdS(质量比,下同)为1∶3时,催化剂具有最优的光催化活性;(5)在50 m L结晶紫浓度为10 mg/L的溶液中,添加0.1 g最优催化剂后,采用350 W氙灯对其光照150 min时,结晶紫的降解率为95.1%;(6)最优催化剂具有良好的重复使用性能,重复使用5次时,对结晶紫的降解率为90.4%.研究显示,结晶紫降解的最终产物为CO2和H2O,催化剂对结晶紫的降解机理是以羟基自由基氧化为主和超氧基氧化为辅的共存氧化机理.In order to obtain photocatalytic material with better catalytic activity to realize efficient degradation azo dyes,sulfydryl kaolin coated CeO2-CdS was synthesized using sodium thioglycollate as sulfur source and modifier of kaolin. The optimum synthesis conditions of the as-prepared materials were confirmed by using photocatalytic degradation of crystal violet as model reaction. The as-prepared materials were characterized by X-ray diffraction,scanning electron microscope,transmission electron microscope,UV-Vis diffuse reflectance spectra and Fourier transform infrared. The results indicated that the catalyst consists of cubic-phase CdS and fluorite-phase CeO2 structures,which formed a basic layered structure of sulfydryl kaolin after the CdS and CeO2 were destroyed. The catalyst exhibited its highest photocatalytic activity for the degradation of crystal violet at a CeO2∶ CdS molar ratio of 4 ∶ 6 and mass ratio of sulfydryl kaolin to CeO2-CdS of 1 ∶ 3. It should be noted that the adsorption edge of the sulfydryl kaolin/CeO2 was predicted to be 450 nm,whereas the optimum catalyst showed strong absorption at 550 nm. The crystal violet was decolorized by 95. 1% within 150 min under a 350 W Hernia lamp at an initial concentration of 10 mg/L in a 50 m L solution in the presence of 0. 1 g of the optimized catalyst. The optimized catalyst exhibited a good repeatability with a removal rate of the crystal violet as high as 90. 4% after 5 cycles. The related mechanistic experiments indicated that crystal violet was eventually decomposed to form CO2 and H2 O. Hydroxyl and superoxide radicals were identified as the primary and secondary active species,respectively,in the degradation of crystal violet.

关 键 词：硫化镉 二氧化铈 高岭土 光催化 巯基乙酸钠 

分 类 号：X51[环境科学与工程—环境工程]