Effect and mechanism of arsenic removal from water by schwertmannite/persulfate enhanced with light
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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