二氧化钛(P25)光催化降解二苯砷酸的研究

二苯砷酸(diphenylarsinic acid,DPAA)是经化学武器泄漏而产生的一种含苯基的有机砷化合物,具有较强的生物毒性,严重威胁生态环境的安全.目前关于降解DPAA方法的研究较少.前期研究发现利用光催化剂二氧化钛(P25)能快速降解DPAA,本实验在此基础上主要研究该催化剂对DPAA的吸附特征、光催化降解动力学及其影响因素,并利用活性氧猝灭剂实验进一步了解各活性氧基团在光反应中的贡献.结果表明,P25光催化降解DPAA可以分为表面吸附与光反应两个阶段,并可用Langmuir-Hinshelwood反应动力学模型拟合.溶液中离子强度和酸碱度的变化会引起光催化剂对DPAA吸附量的改变,进而引起反应速率的改变,反应速率随吸附量的减小而下降.溶液中溶解氧也能促进二氧化钛对DPAA的催化降解.活性氧猝灭实验发现羟自由基在催化反应中贡献最大.

Photo-catalytical Degradation of Diphenylarsinic Acid by TiO2(P25)

Diphenylarsinic acid (DPAA) is the major contaminant in environment polluted by abandoned chemical weapons. DPAA poses high risks to biota but remediation methods for this contaminant are rare. Previous research showed DPAA could be degraded within a short time by TiO₂(P25). Here the kinetics of DPAA degradation catalyzed by P25 was studied. Results showed the photo-catalytical degradation of DPAA by P25 consisted of two processes: adsorption and photo-reaction. The whole reaction could be fitted by Langmuir-Hinshelwood kinetics. Variation in pH and ionic strength caused change in adsorption of DPAA onto the TiO₂ catalyst, which led to the change of reaction rate, showing a decreasing trend with the decreasing adsorption amount of DPAA. Dissolved oxygen promoted the catalytical degradation of DPAA by TiO₂, and the hydroxyl free radical played the most important role in the photodegradation of DPAA, which was testified through quenching experiments with free radical scanvengers.