Removal of Heavy Metals From Aqueous By Thephosphate Dihydrate Dicalcium.

Abstract

The objective of this work is the use of dicalcium phosphate dihydrate CaHPO4, 2H2O (SAP) for the decontamination of aqueous solutions charged in divalent metal ions Cu2+, Zn2+ and Cd2+. After realization of a reliable experimental protocol giving reproducible results, the metals of aqueous solutions are analyzed by flame atomic absorption spectroscopy. The Mass balance before and after extraction makes possible the determination of the rate of metal retention R of the apatitic support. The obtained results show that the R values are closely related to the concentration of metal and the imposed pH in the supernatant solution. Indeed, at low concentrations of Cu2+ ions (10-4M) the R value is close to 0.08. The increase of the pH favours the fixation of the Cu2+ ions on SAP (R passes from 0.058 to 0.085, respectively for pH= 3.5 and 6.5). The kinetic study shows that the mechanism of fixation of the Cu2+ ions by SAP is controlled by a cation exchange: Ca2+ (SAP) /Cu2+ (Solution). The application of SAP to the treatment of metal mixtures of ions leads to a selective extraction: Cd > Zn > Cu.