紫外光协同TiCl_4去除水中As(Ⅲ)效能及动力学

在UV辐照射条件下,研究了钛盐混凝剂(TiCl_4)同步光催化氧化-混凝对水中As(Ⅲ)的去除效率及动力学特征。结果表明,TiCl_4对As(Ⅲ)的去除率在等电点附近(pH=5)达到最大,单一TiCl_4对As(Ⅲ)的去除率为73%;而增加UV辐照后,其去除效率增加至99%。UV/TiCl_4将As(Ⅲ)氧化为更易被絮体吸附的As(V)是去除率增加的主要原因。As(Ⅲ)的氧化吸附速率符合1级反应动力学模型,在pH=5～7内,其速率常数kO呈现出先增加后减小的变化趋势,在pH=6时达到最大(k_O=1.00 min^-1);溶液中总砷(As(Ⅲ)+As(V))的吸附速率也符合1级动力学模型,且速率常数在pH=5～7内随pH的增加而增大,最大可达2.27 min^-1。

Efficiency and Reaction Kinetics for Arsenic Removal from Aqueous Solutions Using UV Combined TiCl_4 Process

Efficiency and reaction kinetics for arsenic removal from aqueous through synchronous photocatalytic oxidation-coagulation by TiCl4 under UV irradiation were studied. The results showed that the maxnium removal effiency of As(Ⅲ) was 73% at pH=5 by single TiCl4 without UV irradiation, however the the removal effiency of As(Ⅲ) was increased to 99% by the UV/TiCl4, the main reason was As(Ⅲ) was oxidated to As(Ⅴ) which was easy to adsorption. The oxidation adsorption rate of As(Ⅲ) followed the first-order kinetics model. The oxidation rate constant first increased and then decreased with pH from 5 to 7, and had a maximum (1.00 min^-1) at pH=6. Adsorption rate of total arsenic from solutions also followed the first-order kinetics model, and the adsorption rate constant increased with the increase of pH in the range of 5 to 7, and had a maximum (2.27 min^-1) at pH was 7.