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ZERO-VALENT IRON FOR HIGH-LEVEL ARSENITE REMOVAL
Citation:
Lien, H. AND R T. Wilkin*. ZERO-VALENT IRON FOR HIGH-LEVEL ARSENITE REMOVAL. Presented at 226th National Meeting of the American Chemical Society, New York, NY, September 07 - 11, 2003.
Impact/Purpose:
To inform the public.
Description:
This study conducted by flow through column systems was aimed at investigating the feasibility of using zero-valent iron for arsenic remediation in groundwater. A high concentration arsenic solution (50 mg l-1) was prepared by using sodium arsenite (arsenic (III)) to simulate groundwater at a heavily contaminated Superfund site in the USA. Flow-through columns were conducted at a flow rate of 17 ml hr-1 under reducing conditions for 6.6 months. Kinetic analysis suggested that arsenic removal behaves as a zero-order reaction at high arsenic concentrations. Arsenic removal capacity of zero-valent iron was determined to be approximately 7.5 mg-As/g-Fe. Carbonate green rust was identified from the analysis of surface precipitates; arsenite uptake by green rust may be a major mechanism responsible for arsenic remediation by zero-valent iron. Analysis of HCl-extractable arsenic from iron samples indicated that approximately 28% of arsenic was in the form of arsenate.