煤矸石-H_2O_2体系对水中As(Ⅲ)的氧化及去除

Oxidation and Removal of As(Ⅲ) in Wastewater by Using Coal Gangue-H_2O_2 Coexist System

对煤矸石进行预处理后用于模拟砷污染水体的处理,采用批量单因素试验,考察了煤矸石对水中As(Ⅲ)的去除效果,研究了H_2O_2对不同浓度As(Ⅲ)的氧化效率及煤矸石-H_2O_2共存时对水中As(Ⅲ)去除效果提高的程度及原因。结果表明:相同条件下,煤矸石粒径越小对水中As(Ⅲ)的去除率越高;对于500μg·L-1的As(Ⅲ)溶液,煤矸石的投加量为40 g·L-1时可达到50.50%的去除率;pH值对煤矸石去除As(Ⅲ)的效果影响作用不大;高温有利于反应过程的发生;煤矸石对As(Ⅲ)吸附符合颗粒内扩散模型和Langmuir吸附等温式模型,吸附速率由膜扩散和颗粒内扩散联合控制,且吸附属于均匀介质表面的单层吸附;H_2O_2可促使As(Ⅲ)转化为As(Ⅴ),H_2O_2浓度越大,氧化效率越好;煤矸石和H_2O_2共同作用对As(Ⅲ)氧化及去除效果的提高主要是由于煤矸石矿物成分中的Fe与H_2O_2之间形成的芬顿效应。

Coal gangue was pretreated for the treatment of arsenic contaminated water.Batch single factor experiments were studied to investigate the effect of coal gangue on the removal of As(IE)in wastewater.Besides,the oxidation efficiency of As(IE)with H2 0 2 single and the removal of As(IE)in water with the coexist of coal gangue and H20 2were also analyzed separately.The results show that under the same conditions,the smaller coal gangue particle size,the better removal rate.For the 500 ug.L^-1 As(IE)solution,removal efficiency can reach to 50.5 0%when the dosage is 40 g.L^-1.pH has little effect on the removal of As(Ⅲ)while the high temperature is beneficial to the reaction process.The adsorption of As(Ⅲ)by coal gangue can be better fitted with the intragranular diffusion model and the Langmuir adsorption isotherm model.The adsorption rate is controlled by both membrane diffusion and intragranular diffusion,and adsorption belongs to the monolayer adsorption on homogeneous medium.The higher the concentration of H2 0 2,the better the oxidation efficiency for As(IE)to As(V).The effect of coal gangue and H2 0 2 on the oxidation and removal of As(Ⅲ)is mainly due to the Fenton effect formed between Fe and H20 2 on the surface of coal gangue.