有机羧酸对蒙脱石光催化转化水中双酚A的影响

Effect of organic carboxylic acids on bisphenol A photocatalytic degradation by montmorillonite minerals

为了研究有机羧酸和黏土矿蒙脱石之间的相互作用引发的光化学过程对污染物迁移转化的影响,选择2种常见的有机羧酸草酸和柠檬酸,在250W的金属卤化物灯(λ≥365nm)照射下,研究了草酸和柠檬酸对天然蒙脱石和蒙脱石KSF光催化降解内分泌干扰物双酚A(BPA)的过程,探讨了反应pH值、溶解氧对BPA光降解的影响.实验结果表明:草酸、柠檬酸可以促进蒙脱石光催化降解水中BPA,特别是对于天然蒙脱石,草酸和柠檬酸可以显著提高其光催化氧化能力,1h的光反应,BPA的降解率分别约为95%和84%,降解动力学符合Langmuir-Hinshelwood方程,同时降解率受pH值的影响较大,在pH值2.0~4.0范围内,随着pH值的增大而增大,当pH=4.0时达到最大,然后迅速减小.溶解氧的存在有利于促进体系中BPA的光降解.

To research the effect of the photochemical process induced by the interaction between organic carboxylic acids and montmorillonite clay minerals on the pollutants migration are ubiquitous in terrestrial and aquatic ecosystems,two classical organic carboxylic acids,oxalate acid and citric acid,were investigated.The effects of organic carboxylic acids on the bisphenol A(BPA) photocatalytic degradation by nature montmorillonite or montmorillonite KSF under the irradiation of a 250 W metal halide lamp(λ≥365nm) were studied.The affecting factors of pH values and dissolved oxygen were discussed in detail.The results of photodegradation experiments show that oxalate acid and citric acid can enhance the BPA photocatalytic degradation in montmorillonite clay minerals suspensions.Especially for the nature montmorillonite suspensions,the two organic carboxylic acids can obviously improve the photocatalytic oxidation capability,and after 1h photoreaction,the ratios of photodegradation are 95% and 84% respectively.The photodegradation rate of BPA is in accord with the Langmuir-Hinshelwood equation.The ratio of photodegradation is dependent on the pH values of the solution.It increases with increase of the pH values ranging from 2.0 to 4.0,and reaches the maximum at pH 4.0.The results also indicate that dissolved oxygen can facilitate the BPA photodegradation in our experiments.