Retention of Cadmium and Zinc from Aqueous Solutions by Poly(acrylic Acid)-Assisted Ultrafiltration

Cadmium and zinc removal from aqueous solution by polyelectrolyte enhanced ultrafiltration (PEUF) process was investigated using poly(acrylic acid) (PAA) with an average molecular weight of 100 kDa. The ultrafiltration studies were carried out using a tangential cell system equipped with 10.000 MWCO regenerated cellulose. Several parameters, such as transmembrane pressure, PAA concentration, pH and ionic strength, have been optimized to improve the retention of the metal ions. The removal of Cd2+ and Zn2+ is more than 96% and 94%, respectively, when each ion was studied separately. The study of pH effect on the cadmium and zinc recovery reveals retentions almost around 85% and 78% respectively at pH 5. Selectivity was studied using a solution containing the two metal ions. It was found that zinc retention decreases compared to single metal solutions, which is more significant in the case of cadmium ions.