Heavy metal-soluble starch xanthate interactions in aqueous environments

The effectiveness of the water-soluble starch xanthate (SSX) process for re moval of heavy metals [Hg(II), Cu(II), Cd(II) and Ni(II)] has been evaluate d. Removal of Hg(II) and Cu(II) is effective; Cd(II) and Ni(II), less so. T he 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 chemi cal interaction between metal and SSX and on separation of the metal-xantha te complex from the aqueous phase. An analogy between the metal-SSX system and the colloid-cationic polyelectrolyte system (coagulation and flocculati on in water treatment) is observed. The role of ionic strength for metal-SS X system appears to be analogous to the role of indifferent electrolyte in coagulation and flocculation. (C) 1999 John Wiley & Sons, Inc.