Effects of Humic Acid, Calcium and Bicarbonate on Arsenic(V) Removal from Groundwater by Zero-Valent Iron
The effects of humic acid (HA), Ca2+ and HCO3-on the arsenic(V) removal from groundwater by zero-valent iron (Fe0) were investigated using batch experiments. Arsenic was removed from groundwater, possibly by adsorption and co-precipitation, with the iron corrosion products. Ca2+ was observed to enhance significantly the removal of arsenic due to its aggregation with iron corrosion products. Higher Ca2+ concentration resulted in a faster removal rate of arsenic in the absence of HA. However, the presence of HA diminished the positive role of Ca2+ because of the formation of soluble Fe-humate complexes and the dispersion of colloidal iron corrosion products by HA in the groundwater. In the co-presence of Ca2+ and HCO3 -, the removal rate of arsenic increased with the higher concentrations of HCO3 -, which could result from the formation of CaCO3 and subsequently contribute to the aggregation of iron corrosion products. In the co-existence of HA, Ca2+ and HCO3 -, HA delayed the aggregation of iron corrosion products and thus inhibited the removal of arsenic. However, after the binding capacity of HA with dissolved iron was saturated, the presence of Ca2+ and HCO3-resulted in rapid aggregation of Fe-humate complexes and colloidal iron corrosion products and thus the removal of arsenic was significantly enhanced.
adsorption aggregation arsenic(V) bicarbonate calcium natural organic matter zero-valent iron
Mark S.H.MAK Pinhua RAO Irene M.C.LO
Department of Civil and Environmental Engineering,The Hong Kong University of Science and Technology Department of Civil and Environmental Engineering,The Hong Kong University of Science and Technology
国际会议
2009 International Symposium on Environmental Science and Technology(2009环境科学与技术国际会议)
上海
英文
971-978
2009-06-02（万方平台首次上网日期，不代表论文的发表时间）