Arsenic extraction from aqueous solution: Electrochemical oxidation combined with ultrafiltration membranes and water-soluble polymers

Abstract

This study shows that the combination of the liquid-phase polymer based retention technique with the electrocatalytic oxidation of arsenic(III) to arsenic(V) is an effective process to remove hazardous As(III) species from aqueous solution. The solution of arsenite and water-soluble polymers at 20:1 polymer:As(III) molar ratio (As(III) 7.5 × 10 −4 M, water-soluble polymer 15 × 10 −3 M) was submitted to electrocatalytic oxidation using (carbon/polymer/Pt) nanocomposite modified electrode at +0.7 V vs. Ag/AgCl and water-soluble polymer as a support electrolyte and extracting agent. After the exhaustive oxidation of As(III) to As(V), the arsenic was placed in the ultrafitration cell and the retention capacity of the water-soluble polymer was studied at different pH. At basic pH, the arsenic retention reached was between 70% and 100%, and the maximum for water-soluble polymer was obtained with chloride as a counter ion: 100% for P(ClDDA), 94% for P(ClAPTA) and 70% for P(SAETA) at Z = 10. The enrichment method shows the maximum retention capacity for arsenate anions in aqueous solutions at pH 9. The type of anion exchanger was an important factor in the maximum retention capacity of arsenate.