分光光度法测定二氧化钛悬浮体系中甲基橙及光催化降解效果的表征

Direct Determination and Photocatalytic Degradation of Methyl Orange by Three-wavelengths Spectrophotometry in the Titanium Dioxide Suspension System

首次利用三波长分光光度法在二氧化钛(TiO2)悬浮体系中直接测定了甲基橙(AO)并用于光催化降解效果的表征.根据三波长原理,用计算机程序选出的最佳三波长组合为420、476和516 nm.在浑浊度不同的二氧化钛悬浮体系中,用三波长法直接测定了标准加入的甲基橙,其回收率为96.7%～101%;同样,在浑浊度一定的悬浮体系中,测定了不同浓度的甲基橙,回收率为99.0%～101%.该法用于表征紫外光照射下的二氧化钛(P25,TiO2纤维)光催化降解甲基橙实际体系,其实际效果与常规测量体系得出的结论完全一致,且不同浑浊度下测量结果的重现性良好.结果表明,三波长分光光度法可以有效地消除悬浮体系中浑浊的干扰,为实现二氧化钛光催化体系的在线监测及光催化降解机理的动力学研究提供了一条可行的途径.

The concentration of methyl orange （AO） was directly determined and the effect of AO photocatalytic degradation was examined by three-wavelength spectrophotometry in the titanium dioxide （TiO2 ） suspension systems. The three optimum wavelengths, 420 nm, 476 nm and 516 nm, were obtained by the theory of three-wavelength spectrophotometry. The concentration of standard methyl orange added was directly determmed in TiO2 suspension systems with various turbidities by this method, and the recoveries were 96.7% - 101%. Also, the recoveries of methyl orange with different concentrations were found to be 99.0% - 101% in TiO2 suspension systems with a fixed turbidity. The method was applied to the real system in which methyl orange had been degraded by TiO2 （P25, TiO2 fiber） photocatalysis with ultraviolet irradiation. It was found that the actual result was confirmed by agreement with the result from routine method, and the repeatability of measurement results in various turbidities was satisfying. The results show that three-wavelength spectrophotometry can efficiendy eliminate the turbidity interference in TiO2 suspension system, which provides a feasible approach for monitoring the reaction of TiO2 photocatalysis on line and for studying the reaction kinetics of photocatalytic degradation.