偶氮染料4BS光解动力学和总氮脱除的初步研究

采用单独紫外光氧化降解偶氮染料直接耐酸大红(4BS)，研究了不同因素对4BS光解效果的影响，并初步考察了光解对4BS溶液总氮的去除效果. 结果表明，单独紫外光氧化法对4BS及溶液中的总氮有一定的去除效果. 在非强碱性条件下，4BS的光解过程符合准一级反应动力学模型. 速率常数随紫外光强的增强而增大，并且与初始ρ(4BS)呈负相关关系. 溶液pH是影响光解反应的重要因素，速率常数随pH升高而增加显著，强碱性条件下光解速率最快. 光解对溶液中总氮的去除分为三步，含氮结构的发色基团易吸收紫外光，在反应初期被降解而生成气态含氮物，生成的中间产物比较稳定，需要经过一段时间的能量积累才能继续降解，从而总氮的去除率再次升高. 

Preliminary Study on Photolytic Kinetics of Azo Dye 4BS and Removal of Total Nitrogen

The degradation of azo dye named Direct Fast Scarlet (4BS) by UV radiation was studied. The main influencing factors and the removal of total nitrogen in 4BS solution were discussed. Experimental results showed that the photolytic degradation of 4BS and total nitrogen in solution by UV irradiation alone was efficient in some sense. The rate of 4BS photodecomposition followed pseudo first-order kinetics under non-strong alkaline condition and the rate constant for thedegradation of 4BS increased with an enhancement in the intensity of UV irradiation and negatively correlated with initial concentration of 4BS. The efficacy ofphotolytic reaction depended strongly on the pH of solution and the rate constant was elevated markedly when pH increased, and reached the highest in strong alkaline aqueous solution. The total nitrogen in solution was removed following three stages. The azo chromophore that absorbed light was easily decomposed into gaseous nitrogenous compounds in the primary reaction, but the stable intermediate product generated in photolytic process could not be removed readily unless the accumulated energy was enough, and then the removal ratio of total nitrogen was enhanced.