Comparative study on lead(II) and cadmium(II) recovery from solutions by chemical precipitation [articol]

Abstract

The paper presents a study regarding a possible way for the removal and the recovery of lead (II) and cadmium (II) ions from wastewaters with relatively high concentrations. The proposed method is based on the precipitation of the metal ions as oxalates with low solubility in water. A systematic study to establish the optimum conditions for a high degree of metal recovery as lead oxalate and cadmium oxalate is presented. The studied parameters were: the pH, the excess of reactant reagents, the initial concentration of ions and the temperature. The crystalline products obtained correspond to: anhydrous lead (II) oxalate (PbC2O4) and trihydrate cadmium oxalate (CdC2O4*3H2O). The extraction degree of metals was around 99% for lead (II) and lower, around 70% for cadmium (II). A possible technological flux for the removal of the studied ions from wastewaters as crystalline oxalates is proposed.