TiO2/UV/O2和TiO2/UV/N2体系降解水中对氯硝基苯

以商用TiO₂P25为催化剂,分别在TiO₂/UV/O₂和TiO₂/UV/N₂两种体系下进行降解对氯硝基苯(pCNB)试验.采用ESR对两种体系下光催化反应形成的·OH进行测定,利用LC-MS对两种体系下反应形成的中间产物进行了定性和定量分析,最后对pCNB降解过程中氯和硝基的存在形式进行了研究.结果表明:TiO₂/UV/O₂体系的催化降解效果要明显优于TiO₂/UV/N₂体系;两种反应体系都有·OH产生,并且TiO₂/UV/O₂体系产生的·OH的量多于TiO₂/UV/N₂体系产生的·OH的量;TiO₂/UV/O₂体系形成的中间产物的种类要多于TiO₂/UV/N₂体系形成的,苯环上的氢、氯、硝基均可被·OH取代形成对硝基酚(pNP)、5-氯-2-硝基酚(5-C-2-PN)等酚类物质;两种体系下均有Cl^-和NO₂^-存在,其中Cl^-生成势与pCNB的去除势一致,只有TiO₂/UV/O₂体系中存在NO₃^-.

The Degradation of p-Nitrochlorobenzene in Aqueous Solution by TiO2/UV/O2 and TiO2/UV/N2 System

The photocatalytic degradation of p-nitrochlorobenzene(pCNB) was studied using two different catalytic system——TiO2/UV/O2 and TiO2/UV/N2.The main intermediate products in the two systems were identified and quantified by means of HPLC-MS,the modality of chlorine and nitryl on pCNB was studied during the photocatalytic degradation reaction,at last, the hydroxyl radicals in these two different catalytic systems were detected.Results showed that the efficiency of the degradation of pCNB in TiO2/UV/O2 system is much better than that of TiO2/UV/N2 system;the hydroxyl radicals was formed in both of the two systems,but the quantity of the hydroxyl radicals is much more than that of TiO2/UV/N2 system;the main intermediate products in TiO2/UV/O2 system is much more than that of TiO2/UV/N2 system,and p-nitrophenol(pNP),p-chlorophenol(pCP),5-chlor-2-nitrophenol(5-C-2-PN) were the same intermediate products in both of these two systems;Cl-and NO2-were detected in both of these two reaction systems,and NO3-was detected only in the TiO2/UV/O2 system.