UV降解水溶液中吲哚美辛的动力学研究

以中压汞灯为光源,研究水环境中吲哚美辛(IDM)的紫外光降解机制.实验结果表明,IDM的光解反应符合准一级动力学规律,其降解速率常数随自身浓度的增大而减小,当IDM浓度由1 mg·L~(-1)增至12 mg·L~(-1)时,其速率常数由0.0148 min~(-1)减至0.00412 min~(-1).通过模型研究IDM的紫外光解机制时发现,其降解包括直接光解和自敏化光解,直接光解常数为0.0151 min~(-1).研究环境因子对IDM光解的影响时发现,碱性环境有利于IDM的降解,而溶解氧抑制IDM的光解,腐殖酸通过光掩蔽和自由基猝灭两个作用抑制IDM的光解,硝酸根通过接受光量子产生·OH促进IDM的降解,并通过竞争反应实验测得·OH稳态浓度为2.10×10~(-1)4mol·L~(-1),IDM与·OH的二级反应速率常数为9.86×109L·mol~(-1)·s~(-1).

Photodegradation kinetics of indometacin by UV radiation in aqueous solution

The mechanism of IDM photodegradation in aqueous media was investigated under UV light by a medium pressure mercury lamp. The results demonstrate that the photodegradation of IDM followed pseudo-first-order kinetics. The photodegradation rate decreased with larger initial concentrations, from 0.0148 min^-1 to 0.00412 min^-1 as the concentration was elevated, from 1 to 12 mg·L^-1. Photodegradation of IDM included degradation by direct photolysis (0.0151 min^-1) and by self-sensitization via ROS. In this paper,the effects of environmental factors on the photodegradation of IDM were also studied. The results show that alkalinity increased the photodegradation of IDM while dissolved oxygen had an inhibitory effect on the direct photodegradation. Humic substance inhibited the photodegradation via both attenuating light and competing ·OH. NO₃^- increased the photodegradation of IDM via producing ·OH from accepting the light quantum, and the second-order rate constant for the reaction of IDM with ·OH was observed by a competition kinetic experiment to be 9.86×10⁹ L·mol^-1·s^-1 according to the calculated steady state ·OH concentration of 2.10×10^-14 mol·L^-1.