还原法和活性炭吸附法去除水体中Cr(Ⅵ)的改进

摘要

在优化还原法和改性活性炭吸附法应用于水体中Cr(Ⅵ)的去除效果的基础上,探讨还原法-改性活性炭吸附法的联用及效果.结果表明:采用正交试验及2次验证试验优化了还原法对水体中Cr(Ⅵ)的去除,得到了焦亚硫酸钠、亚硫酸氢钠、亚硫酸钠、连二亚硫酸钠和硫代硫酸钠分别作为还原剂的还原法的优化条件,在该条件下,各还原剂对水体中Cr(Ⅵ)的去除率可达到96.59％～99.48％.以不同浓度硝酸锰分别对活性炭进行改性,其效果差别较大,但都优于未改性活性炭,其中,当硝酸锰浓度为0.03 mol·L-1时,所得的改性活性炭对水体中Cr(Ⅵ)的去除率最高,且去除率受pH、初始Cr(Ⅵ)浓度和处理时间的影响较大,pH为3时,去除率最高(94.6％),对水中初始浓度较低的Cr(Ⅵ)的去除效果较好,在吸附的初、中期,Cr(Ⅵ)的去除率增长较快.还原法-改性活性炭吸附法联用优于单独应用还原法或改性活性炭吸附法,以该联用法对海甸溪水模拟Cr(Ⅵ)污染样品的处理结果表明,联用法对实际基体样品的处理取得了令人满意的效果.%Experimental conditions for reduction method and activated carbon adsorption method were optimized to remove Cr (Ⅵ) in water,and both methods were combined to observe their effect on removal of Cr(Ⅵ).The orthogonal experiments and double-check test were used to optimize the reduction method for removal of Cr(Ⅵ),resulting in optimum conditions for the reduction method with sodium metabisulfite,sodium bisulfite,sodium sulfite,sodium hydrosulfite and sodium thiosulfate as reducing agents.Under these optimal conditions,the reducing agents had a Cr(Ⅵ) removal rate of 96.59 ％-99.48％ in the water body.Activated carbon modified with manganese nitrate at different concentrations produced different effects on Cr (Ⅵ) removal and had the highest removal rate when modified with manganese nitrate at the concentration of 0.03 mol/L.The modified activated carbon had better removal effect than the unmodified one.The removal rate was affected by pH,initial concentration of Cr (Ⅵ) and treatment time.When the pH was 3,the removal rate was the highest (94.6％).The modified activated carbon had better removal effect when the contaminated water contained lower initial concentration of Cr(Ⅵ),and the Cr(Ⅵ) removal rates increased fast at the early and middle stage of absorption.The combined reduction and modified activated carbon absorption method had better effect on removal of Cr(Ⅵ) than the reduction method or the modified activated carbon absorption method alone.The simulated water samples collected from Haidian Stream,Haikou,Hainan,China were treated by using the combined reduction and modified activated carbon adsorption method,and the results showed a satisfactory treatment of the actual sample matrix by using the combined method.