偶氮染料的臭氧氧化机理研究

Ozonation mechanism of azo dye

在3.5L半序批式反应器中进行了阳离子红X-GRL偶氮染料的臭氧氧化实验.用GC/MS定性和GC半定量等方法确定了该染料在臭氧氧化过程中各中间产物的出现次序及浓度变化,结合臭氧与染料反应的化学计量比、反应过程中溶液pH的下降和NO3-的生成,得出了染料的臭氧氧化机理可分为三个阶段,即:助色基脱落、最大吸收峰紫移阶段;生色基分解、染料脱色阶段;无色中间产物进一步降解成有机酸、醛、酮及烷烃等有机小分子阶段.确定了染料分子中6个氮的转化路径,即:其中4个氮原子转化为2分子N2,另外2个氮原子分别转化为1分子有机氮化合物和1分子NO-3.染料的臭氧氧化以直接氧化为主.

The degradation mechanism of the Cationic Red X-GRL azo dye in a 3.5 L semi-batch reactor by ozonation was studied after the intermediates, the nitrate ion, and the pH were detected in the reaction by the use of some analytical instruments such as GC/MS, GC, and IC. The degradation of Cationic Red X-GRL includes three stages: the de-auxochrome stage which shifts the maximum absorbance peak of the dye from 530 nm to 522 nm; the decolouring stage which cleaves the chromophore; and the decomposition of fragments stage in which the intermediates split into various organic acids, ketones, aldehydes, and alkanes. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transformed into a nitrate ion, one takes the form of an amine compound, and the other four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct reaction of ozone is the main decolouring effect.