Effects of dissolved ions and natural organic matter on electrocoagulation of As(III) in groundwater

Abstract

Electrocoagulation is an outstanding technique to remove pollutants. When current is applied to electrodes, various amorphous iron hydroxides form complexes. Those complexes with high absorption capacity such as arsenic and heavy metals are removed through the process. In this study, the effects of various electrocoagulation conditions, such as the type of electrode, current, and pH, on the removal efficiency of arsenic were investigated. The removal efficiency varied significantly depending on the type of electrode, as an iron electrode showed superior arsenic removal as compared to an aluminum electrode. As the current increased, the removal rate of arsenic has increased. The validity of the method was examined by calculating the metal elution during electrocoagulation using Faraday’s law and comparing it to the actual elution amount. Notably, amongst the various pH conditions pH 7 generated the fastest removal rate. The effects of dissolved ions on arsenic removal were also examined. When the magnesium concentration was less than 10mg/L, the initial arsenic removal speed increased. No effects were observed when the concentration of sulfate ions was low (1mg/L, 10mg/L). When the concentration of sulfate ions was high (100mg/L), the arsenic removal rate decreased. In addition, the presence of phosphate ions and humic acid (HA) are reversely correlated with arsenic removal rate.