Characterization of a Ca-alginate based ion-exchange resin and its applications in lead, copper, and zinc removal

Characterization of a novel ca-alginate based ion-exchange resin and its application in metal removal were investigated. The metal removal percentages increased from almost 0 to nearly 100% for metal concentrations < 0.1 mmol/L at pH 1.2 to 4, and a plateau was established at pH > 4. The removal percentages were in the following order: Pb2+ > Cu2+ > Zn2+ at pH < 4. Lower initial concentrations and ionic strengths slightly enhanced the removal percentage. The maximum metal removal capacities (q(max)) were 2.01 and 2.04 mmol/g for lead and copper, respectively, which are much higher than activated carbons and other reported biosorbents. Competitive effects were important for zinc removal, but less significant for lead and copper uptake. Organic chemical leaching from the resin was negligible. The single- and multiple-species metal ions were removed completely within approximately 90 and 130 minutes, respectively. The lead removal became much faster when its concentration was decreased and in the absence of other metal ions. Presence of competitive metal ions significantly reduced the metal uptake rate. Removal process kinetics were controlled by the mass transfer, while the local equilibrium followed an ion-exchange relationship.