Oxidation and Removal of Arsenic From Groundwater by Zero-Valent Aluminum.

Abstract°G

    Arsenic contamination in groundwater has raised the public concern since it is toxic and carcinogenic. Therefore, the World Health Organization (WHO) lowered the maximum contaminant level for arsenic in drinking water from 50 to 10 £gg/L. Many methods are currently used for oxidating and removing As from groundwater. Previous studies often use zero-valent iron(ZVI) to produce Fenton reagent to oxidate As(III), but they found that oxidation capacity of As(III) by ZVI/O₂ limited. An increase in solution pH due to the generation of hydroxide ions and the formation of iron hydroxide precipitates. This result decreases the overall oxidative capacity because ZVI-mediated H₂O₂ formation and the following Fenton reaction is effective only at acidic pH(pH < 4). In this experiment, zero-valent aluminum(ZVAl) Substituted ZVI to generate H₂O₂ in the presence of dissolved oxygen, and adding Fe(II) to occur Fenton reaction. Preliminary finding 5oo ppb As(III) totally oxidized in 3hr, and the concentration of H₂O₂ produced by ZVAl more than ZVI, and will not be reduce by ZVAl, then making Fenton reaction smoothly. The oxidation rate of ferrous iron is not remarkable when Fe(II) is added. According to the redox potential to judge that generated of Fe (III) in the Fenton reaction can be reduce to Fe(II) by ZVAl. Therefore, sustainable generation Fenton reagent, further improve the oxidation of As(III).The generation OH in solution may lead the Al³⁺ precipitated hence producing Al (hydr)oxide precipitates with highly adsorption capacity, and removal the arsenic in groundwater.