Removal of Arsenic
from water - An Electrochemical Analysis
October 15, 2004
825 SWM, 1:00 PM
& 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.