Sorption Mechanism of some Heavy Metal Ions from Aqueous Media using Magnesium Silicate

The modification of laboratory prepared magnesium silicate (MgSi) by nitric acid has strong effect on its physicochemical properties. Sorption performance of hydrogen rich-magnesium silicate (HMgSi) with respect to Cu2+, Cd+, Ni2 and Fe3+ heavy metal ions has been conducted to evaluate its potential to purify metal finishing wastewaters. According to the equilibrium data, the selectivity sequence can be given as Cu2+>Cd2+>Ni2>Fe3+. Experimental parameters affecting the sorption process such as ph level, contact time, initial metal concentration, competing agents and temperature were studied. The presence of competing ions as well as complexing agents were found to affect the uptake of the studied ions in the order of EDTA>> Pb2+>Mg+ >> Na+. Time variation studies indicated that the sorption processes followed pseudo-second order kinetics. The equilibrium sorption data fitted well to Freundlich sorption isotherm. The thermodynamic parameters were evaluated and the results showed that all sorption processes are spontaneous and endothermic in nature.