CuO/TiO_2-H_2O_2光催化体系中亚甲基蓝脱色机理  

The decoloration mechanism of Methylene Blue in a CuO/TiO_2-H_2O_2 photocatalytic system

作　　者：吉芳英[1] 徐璇[1] 范子红[1] 邱雁[1] 袁云松[1] 

机构地区：[1]重庆大学三峡库区生态环境教育部重点实验室,重庆400030

出　　处：《重庆大学学报（自然科学版）》2009年第6期705-710,共6页Journal of Chongqing University

基　　金：国家自然科学基金资助项目(50278101);教育部博士点基金资助项目(20070611009);重庆大学研究生科技创新基金资助项目(200904A1B0010316)

摘　　要：采用水解法制备了具可见光响应能力的CuO/TiO2光催化剂。通过对不同光源和pH条件下体系中.OH存在量和脱色率的考察,提出了亚甲基蓝光催化脱色的机理。紫外光照射时,酸性条件下体系中有大量.OH生成,.OH扩散至液相中起主要脱色作用;碱性条件下.OH生成量较少,.OH通过与吸附于催化剂表面的亚甲基蓝作用来实现脱色;中性时两者协同作用。该3种条件下脱色率均远高于弱酸和弱碱时。光源为可见光时,光催化体系中电子传递产生回路,各种pH条件下体系中均只有少量.OH生成。酸性和中性条件下.OH必须扩散至液相中与亚甲基蓝反应,脱色率极低;碱性条件下亚甲基蓝被吸附于催化剂表面,.OH利用效率提高,同时由于光敏化作用的存在,使得脱色率极高。A CuO/TiO2 photocatalyst is prepared using the hydrolysis method. It exhibites excellent photocatalytic activity under both UV and Vis light. After investigating the quantity of hydroxyl radicals and the decoloration rate under different pH situations irradiated by UV or Vis light, a new methylene （MB） blue photocatalytic decoloration mechanism is proposed. Under UV light irradiation, methylene blue is decolored by mass hydroxyl radicals which diffuse into the liquid phase in acidic conditions. A few hydroxyl radicals are generated in alkaline conditions, and these radicals affect the MB which is absorbed on the photocatalyst surface. There is a synergistic effect of the above in neutral conditions. The removal rate under strongly acidic, strongly alkaline or neutral conditions is much higher than in weak acid or alkaline conditions. Under Vis light irradiation, fewer hydroxyl radicals exist in this system for an electron-transfer formation loop, and the hydroxyl radicals must diffuse into liquid to react with MB, so the decoloration rates are extremely low under acidic and neutral conditions. A high decoloration rate is achieved under strongly alkaline conditions because MB is absorbed on the surface of the photocatalyst which increases the hydroxyl radical utilization efficiency. Photosensitization also accelerates the decoloration.

关 键 词：光催化 羟基自由基 CuO/TiO2 亚甲基蓝 

分 类 号：X703.1[环境科学与工程—环境工程]