Chemical speciation of inorganic and methylarsenic(III) compounds in aqueous solutions

Abstract

AbstractSpeciation of inorganic and methylarsenic(III) species in aqueous hydrochloric acid solutions has been studied by the solvent extraction method. In a hydrochloric acid–carbon tetrachloride system, inorganic and methylarsenic(III) species formed the corresponding chlorides and were extracted into the organic phase. The extractability of inorganic and methylarsenic(III) species increased as the number of methyl groups attached to the arsenic atom increased. In addition, dimerization of dimethylarsinous acid occurred with decreasing acidity in the aqueous phase. On the basis of the data obtained, we determined the stability constants for the proposed species, and evaluated the effect of methyl groups on the speciation and the reactivity of inorganic and methylarsenic(III) species in aqueous solutions. Copyright © 2002 John Wiley & Sons, Ltd.