Removal and Recovery of Heavy Metals from Simulated Wastewater Using Insoluble Starch Xanthate Process

摘要

The effectiveness of insoluble starch xanthate (ISX) for removal and recovery of heavy metals [Cd(II), Cu(II), Hg(II), and Ni(II)] from simulated wastewater was evaluated. The metal-xanthate interaction is considered as sorption process involving two simultaneous reactions: (1) complexation of metal with xanthate groups; and (2) decomposition of xanthates. The kinetics and equilibrium studies indicate that the rate of metal uptake by ISX is quite rapid and the Freundlich constants indicate that the interaction is chemi-sorption. The metal uptake capacity of ISX remains almost the same in the pH range 5-7. The affinity, and also the selectivity of metals for xanthate, follow the reciprocal of metal-ethylxanthate solubility product. The aqueous phase conditions and ISX dosage can be controlled to selectively remove metals from the aqueous phase containing mixtures of metals [Cd(II), Cu(II), Hg(II), and Ni(II)]. Also selective recovery of metals from ISX sludge containing the metals is feasible.