Sorption materials for arsenic removal from water: a comparative study.

Five different sorption materials were tested in parallel for the removal of arsenic from water: activated carbon (AC), zirconium-loaded activated carbon (Zr-AC), a sorption medium with the trade name 'Absorptionsmittel 3' (AM3), zero-valent iron (Fe(0)), and iron hydroxide granulates (GIH). Batch and column tests were carried out and the behavior of the two inorganic species (arsenite and arsenate) was investigated separately. The sorption kinetics of arsenate onto the materials followed the sequence Zr-AC >> GIH = AM3 > Fe(0) > AC. A different sequence was obtained for arsenite (AC >> Zr-AC = AM3 = GIH = Fe(0)). AC was found to enhance the oxidation reaction of arsenite in anaerobic batch experiments. The linear constants of the sorption isotherms were determined to be 377, 89 and 87 for Zr-AC, AM3 and GIH, respectively. The uptake capacities yielded from the batch experiment were about 7gl(-1) for Zr-Ac and 5gl(-1) for AM3. Column tests indicated that arsenite was completely removed. The best results were obtained with GIH, with the arsenate not eluting before 13100 pore volumes (inflow concentration 1 mg l(-1) As) which corresponds to a uptake capacity of 2.3 mg g(-1) or 3.7 g l(-1).