Removal of zinc and nickel from aqueous solution by chitosan and polyaluminum chloride

Aims: The purpose of this study is to investigate the zinc (Zn) and nickel (Ni) removal from aqueous solution by coagulation-flocculation using polyaluminum chloride (PACl) and chitosan (CS) biopolymer. Materials and Methods: This study was a laboratory scale experiment, which used PACl and CS to remove Zn and Ni with concentrations 3-100 mg/L from aqueous solutions. Jar test was used to compare the Zn and Ni removal efficiencies of the chemical treatment options using PACl and CS. The dosages used for PACl ranged from 5 to 100 mg/L whereas CS dosages varied between 5 and 75 mg/L. Results: The results showed that optimum coagulant doses and pH were found at 50-100 mg/L and 11 for PACl and 20-75 mg/L and 11 for CS, respectively, when CS added with PACl led to a better removal efficiency of the metals (more of 99%). In mixed aqueous solution, the presence of Zn caused increase of Ni removal efficiency and the presence of Ni caused decrease of Zn removal efficacy. Conclusion: The results of this study showed that CS had higher removal efficiency than PACl for removal of Zn and Ni, and also CS as a coagulant aid led to increasing in metal removal.