Fenton法对水中Sb(Ⅲ)和Sb(Ⅴ)的去除研究

Fenton Process for Removal of Sb(Ⅲ)and Sb(Ⅴ)from Wastewater

以浓度为5 mg/L的Sb(Ⅲ)和Sb(Ⅴ)模拟废水作为处理对象,考察了不同时间、pH、H_(2)O_(2)和Fe^(2+)投量下Fe^(2+)/H_(2)O_(2)对水中锑的去除效果,对比了Fenton法和三价铁混凝法的除锑效果,结合X射线光电子能谱技术(XPS)探讨Fenton法对水中锑的去除机理。结果表明,Sb(Ⅲ)和Sb(Ⅴ)的最佳去除条件相同:pH为4.0、Fe^(2+)投量为5.6 mg/L、H_(2)O_(2)与Fe^(2+)的物质的量之比(H_(2)O_(2)∶Fe^(2+))为2∶1、反应时间为40 min,在该条件下,Fe^(2+)/H_(2)O_(2)体系对Sb(Ⅲ)和Sb(Ⅴ)的去除率分别为75.8%和68.9%。当H_(2)O_(2)∶Fe^(2+)在2∶1~8∶1范围内时,体系对Sb(Ⅲ)和Sb(Ⅴ)的去除率基本保持不变;当Fe^(2+)浓度超过5.6 mg/L时,体系对Sb(Ⅲ)和Sb(Ⅴ)的去除率增幅较小,但是剩余铁浓度急剧升高。在pH为3.0~5.0范围内Fe^(2+)/H_(2)O_(2)体系对Sb(Ⅲ)和Sb(Ⅴ)的去除率较高,但随着pH的升高,二者去除率均显著降低,且Sb(Ⅲ)去除率受pH影响更明显。Fenton法对Sb(Ⅲ)和Sb(Ⅴ)的去除率在pH为3.0~5.0范围内均优于三价铁混凝法。XPS分析显示,Sb(Ⅲ)与絮体之间的结合力高于Sb(Ⅴ),这与Fenton体系对两种形态锑的去除作用有关。Fenton法对Sb(Ⅲ)的去除是氧化产生的Fe^(3+)与Sb(Ⅲ)共沉淀、新生态铁对Sb(Ⅲ)的吸附以及对氧化产生的Sb(Ⅴ)的吸附三者综合作用;对Sb(Ⅴ)的去除则主要是新生态铁对Sb(Ⅴ)的吸附作用。

The effects of Fe^(2+)/H_(2)O_(2)system under different reaction time,pH and concentrations of H_(2)O_(2)and Fe^(2+)on Sb(Ⅲ)and Sb(Ⅴ)removal(concentration of 5 mg/L for both)from simulated wastewater were investigated,the antimony removal efficiency of Fenton and ferric coagulation was compared,and the mechanism of antimony removal from wastewater by Fenton process was explored by XPS.The optimal parameters for Sb(Ⅲ)and Sb(Ⅴ)removal were identical:pH of 4.0,Fe^(2+)concentration of 5.6 mg/L,H_(2)O_(2)to Fe^(2+)ratio of 2∶1 and reaction time of 40 min.Under these conditions,the removal rates of Sb(Ⅲ)and Sb(Ⅴ)by Fe^(2+)/H_(2)O_(2)system were 75.8%and 68.9%,respectively.When the ratio of H_(2)O_(2)to Fe^(2+)was in the range from 2∶1 to 8∶1,the removal rates of Sb(Ⅲ)and Sb(Ⅴ)were basically unchanged.When the concentration of Fe^(2+)exceeded 5.6 mg/L,the removal rates of Sb(Ⅲ)and Sb(Ⅴ)increased little,but the residual iron concentration increased sharply.When the pH was in the range from 3.0 to 5.0,Fe^(2+)/H_(2)O_(2)had high removal rates for Sb(Ⅲ)and Sb(Ⅴ).However,with the increase of pH,the removal rates of both Sb(Ⅲ)and Sb(Ⅴ)decreased significantly,and the removal rate of Sb(Ⅲ)was more significantly affected by pH.Fenton process showed better removal performance on both Sb(Ⅲ)and Sb(Ⅴ)compared with ferric coagulation when pH was in the range of 3.0-5.0.The XPS results indicated that the combination between Sb(Ⅲ)and flocs was stronger than Sb(Ⅴ)and flocs,which was related to the removal of the two forms of antimony by Fenton system.The removal of Sb(Ⅲ)by Fenton process was the comprehensive effect consisting of co-precipitation between Sb(Ⅲ)and Fe^(3+)generated by oxidation,adsorption of Sb(Ⅲ)and Sb(Ⅴ)as its oxidation product by newly formed iron oxide.The removal of Sb(Ⅴ)was mainly due to the adsorption by newly formed iron oxide.