Heavy metal-Soluble starch xanthate interactions in aqueous environments

Abstract

The effectiveness of the water-soluble starch xanthate (SSX) process for removal of heavy metals [Hg(II), Cu(II), Cd(II) and Ni(II)] has been evaluated. Removal of Hg(II) and Cu(II) is effective; Cd(II) and Ni(II), less so. The metal [Hg(II)/Cu(II)] binding capacity remains the same in the pH range 3–7. An optimum metal/SSX ratio is observed for maximum metal removal. The metal removal efficiency of SSX appears to be dependent on a specific chemical interaction between metal and SSX and on separation of the metal–xanthate complex from the aqueous phase. An analogy between the metal–SSX system and the colloid–cationic polyelectrolyte system (coagulation and flocculation in water treatment) is observed. The role of ionic strength for metal–SSX system appears to be analogous to the role of indifferent electrolyte in coagulation and flocculation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1325–1332, 1999