不同催化系统降解甲基橙的效率比较及过程分析

Comparison and analysis of degradation study for methyl orange by different catalytic systems

以甲基橙模拟染料废水为降解目标,在自制的圆柱形不锈钢反应器中,比较三种不同的光催化系统:TiO2光催化、紫外光辐射及臭氧单独氧化的催化效率,检测脱色率、COD、pH值影响、臭氧及羟基自由基(·OH)的变化分析催化反应历程。研究表明:三种体系降解150 min后COD降解率分别为46.23%(UV),44.54%(O3)and 74.12%(TiO2),而120 min后脱色率达93.6%(UV),92.07%(O3)and 96.79%(TiO2)。三种体系在酸性条件下COD降解率和脱色率都最高。臭氧和羟基自由基检测显示,催化初期TiO2催化系统产生更多的臭氧,有利于后期·OH的产生。同时,利用·OH计算光催化反应速率也显示TiO2催化效率更好。

The effect of ultraviolet irradiation（ UV） ,ozonation and the TiO2 photocatalysis systems on the decolorization and degra-dation of methyl orange, performed in a laboratory scale reactor, was studied. Decoloration efficiency, chemical oxygen demand （ COD） analysis and concertration changes of ozone and hydroxyl radical（·OH） were employed. The results indicated that the COD removal efficiencies of methyl orange were only 46. 23%（ UV） ,44. 54%（ O3 ） and 74. 12%（ TiO2 ） after 150 mins in three proces-ses,while the corresponding decolorization efficiencies were 93. 6%,92. 07%and 96. 79%after 120 mins treatment. The three cata-lytic systems showed higher decolorization and COD removal efficiency presented in acid condition than alkaline or neutral condi-tion. Based on the concentration of O3 and·OH in different systems,the amount of hydroxyl radicals produced by three systems was greatly affected by the amount of O3 in the early stage of the reaction and the formation rate of hydrogen peroxide in TiO2 photocatal-ysis system would be highest and quickest transfer of ozone to more hydroxyl radicals which could enhance the degradation of the methyl orange.