臭氧提高纳米TiO2光催化活性的ESR分析

以5,5-二甲基-1-吡咯啉-N-氧化物(DMPO)为自由基捕获剂,分别以去离子水和二甲基亚砜(DMSO)为溶剂,利用电子自旋共振(ESR)方法对UV、O₃、TiO₂/O₃、TiO₂/UV/O₂、UV/O₃和TiO₂/UV/O₃这6种体系中形成的羟基自由基(·OH)和超氧阴离子自由基(·O₂^-)进行了检测,同时考察了反应时间、催化剂投量以及体系溶解氧对TiO₂/UV/O₃体系形成·OH和·O₂^-的影响.结果显示,在纳米TiO₂光催化体系中加入臭氧,能显著增加反应体系中·OH和·O₂^-自由基的生成量,6种体系中DMPO-·OH和DMPO-·O₂^-加合物的ESR波谱峰信号强度分别为:TiO₂/UV/O₃>TiO₂/UV/O₂>UV/O₃>UV>TiO₂/O₃>O₃和TiO₂/UV/O₃≈TiO₂/UV/O₂>TiO₂/O₃>UV>UV/O₃>O₃,在TiO₂/UV/O₃体系中成功监测到·O₃^-自由基的存在.

ESR Analysis on the Ozone Enhanced Photocatalytic Activity of Aqueous Nanosized Titanium Dioxide Suspensions

The reaction activities of UV,O₃,TiO₂/O₃,TiO₂/UV/O₂,UV/O₃ and TiO₂/UV/O₃ six different processes were tested in aqueous or dimethylsulfoxide (DMSO) suspensions using elec-tron spin resonance (ESR) technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trap, in the meantime,the effect of different reaction time,amount of catalyst used and dissolved oxygen on the formation of·OH and·O₂^- in TiO₂/UV/O₃ process were discussed.Result showed that the concentration of·OH and·O₂^- increased obviously by adding ozone.The relative intensity of DM-PO-·OH and DMPO-·O₂^- in six different conditions was TiO₂/UV/O₃>TiO₂/UV/O₂>UV/O₃>UV>TiO₂/O₃>O₃ and TiO₂/UV/O₃≈TiO₂/UV/O₂>TiO₂/O₃>UV>UV/O₃>O₃,respec-tively.At last,the DMPO-·O₃^- was successfully detected in TiO₂/UV/O₃ process.