摘要
为探究高砷地下水及高砷废水中砷的有效去除方法,本研究考察了自然光与UV-254光照条件下,施氏矿物/过硫酸盐体系中施氏矿物对水体中砷的吸附去除效果.研究表明:施氏矿物单独作用于高砷废水时,当施氏矿物加入量为0.8 g·L-1,砷浓度为1 mg·L-1时,在暗反应条件下反应2h后,溶液中砷的去除率为47.7％;而在自然光或UV-254光照条件下反应2h后,溶液中砷的去除率接近100％.在施氏矿物加入量为0.8 g·L-1,过硫酸盐浓度为350 μmol·L-1的施氏矿物/过硫酸盐体系中,在暗反应条件下反应30 min,溶液中砷的去除率可达100％;在自然光照条件下反应10 min后,溶液中砷的去除率为100％;而在UV-254光照条件下反应5 min后,溶液中砷的去除率就可达100％.同时,施氏矿物/过硫酸盐共存体系中存在As(Ⅲ)向As(Ⅴ)转化的现象,且光照可以加速As(Ⅲ)向As(Ⅴ)的转化,进而促进施氏矿物对砷的吸附.研究表明,在光照强化施氏矿物/过硫酸盐体系中,光照及硫酸根自由基(SO4-·)可以促进As(Ⅲ)向As(Ⅴ)转化,从而使得施氏矿物对砷的吸附去除能力增强,且UV-254光照作用效果要优于自然光.
Abstract
This study aimed to explore the effective removal methods of arsenic in arsenic-rich groundwater and arsenic-contaminated wastewater.The adsorption and removal effect of arsenic from water by schwertmannite in the schwertmannite/persulfate system under natural light and UV-254 light conditions were explored in this study.The results showed that when the concentration of schwertmannite and arsenic were 0.8 g·L-1 and 1 mg·L-1,respectively,the removal rate of arsenic in the solution was 47.7％after 2 h in the dark,and the removal rate of arsenic in the solution was 100％after 2 h under natural light or UV-254 light when schwertmannite acts alone on arsenic-contaminated wastewater.In the coexistence system containing schwertmannite(0.8 g·L-1)and persulfate(350 μmol·L-1),the removal rate of arsenic in the solution reached 100％after 30 min of reaction in the dark;and the removal rate of arsenic in the solution reached 100％after 10 min under natural light.The removal rate of arsenic in the solution reached 100％after 5 min under UV-254 light.Further studies had confirmed that As(Ⅲ)can be converted to As(Ⅴ)in the coexistence system of schwertmannite and persulfate,and light can accelerate conversion of As(Ⅲ)into As(Ⅴ),which in turn promotes the adsorption of arsenic by schwertmannite.Studies have shown that in the schwertmannite/persulfate system enhanced with light,light and sulfate radicals(SO4-·)can promote the conversion of As(Ⅲ)to As(Ⅴ),thereby the adsorption and removal ability of schwertamnnite for arsenic is enhanced,and the effect of UV-254 light is better than that of natural light.
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