Gas-bubbled nano zero-valent iron process for high concentration arsenate removal

In this study, batch experiments were performed to investigate a novel process for high concentration arsenate removal in the presence of air and/or CO2 bubbling. The pretreatment step. CO2 bubbling at 300 mL/min for 5 min, was taken to adjust the solution pH to an acidic environment, followed by air bubbling at 300 mL/min for 10 min to increase dissolved oxygen in the solution. In the treatment period, the nano-scale zero-valent iron was applied to remove aqueous arsenate of 3000 mu g/L., while the treatment system was continuously bubbled by 300 mL/min of air. Such a process resulted in outstanding performance in arsenate removal. Furthermore, in the field groundwater application, the arsenate removal rate for the proposed process was 5 times faster than the rate measured when the system was pretreated by acidic chemical species only. (C) 2011 Elsevier B.V. All rights reserved.