Removal of Arsenic from water - An Electrochemical Analysis

Friday, October 15, 2004

Room 825 SWM, 1:00 PM

Fabiola Brusciotti

Graduate Student

Earth & Environmental Engineering


Arsenic is present in nature as a result of both geological and industrial processes. It is listed as a hazardous material, and the World Health Organization set the maximum concentration level allowed in drinking water at 10 ppb. Methods of removal currently employed take into account the two common forms of arsenic in water, which are As(V) and As(III). As(V) is less toxic and more easily removed than As(III), so in case As(III) is present, oxidation to As(V) may be required before applying any removal technology.
Experiments for removing arsenic with ferric salts, zeolite or by cementation were performed in order to better understand the conditions for removal. This analysis raised some questions. What is the actual As removal mechanism? Is As(III) oxidized to As(V) and bound to other compounds, or is it reduced and removed as arsenic metal? Which method is more efficient?
In order to answer these questions, an electrochemical analysis of arsenic in aqueous solutions is being performed, using cyclic voltammetry with a rotating disk electrode. This method is very useful to study the rate and reversibility of the reactions taking place in solution. Preliminary results pointed to the irreversibility of such reactions, and to the fact that they are not diffusion-controlled. Further experiments are required to analyze the solutions at different As concentrations and other varying parameters, and to apply the results for As removal by cementation on Zn or other metals.