Abstract:

The thermally activated colloidal pyrite was characterized by XRD and SEM. The effect of solution pH, dissolved oxygen，
and thermal activation temperatures on the performance of thermally activated colloidal pyrite on removal of Cd(Ⅱ) from aqueous solution were systematically studied. The reactive kinetics and the mechanism of the adsorption of Cd(Ⅱ) on thermally activated colloidal pyrite were also discussed. Colloidal pyrite was decomposed into Porous Monoclinic Pyrrhotite (PMPyr) after thermal activation at 650℃ for 5 minutes in a muffle furnace (nitrogen atmosphere). The removal efficiency of Cd(Ⅱ) by PMPyr in the solution of no dissolved oxy gen was above 88% at pH 2~6, suggesting that the removal efficiency of Cd(II) was less affected by pH. Moreover, surface oxidation of PMPyr could restrain the interaction between PMPyr and Cd( Ⅱ). The kinetic adsorption process was well described by pseudo-second-order model with high correlation coefficient (R2> 0.9992). The influence of pH and change of concentration of Fe (Ⅱ) and SO42- showed that the adsorption of Cd(Ⅱ) on PMPyr was mainly dominated by ion exchange and surface complexation.

Key words: colloidal pyrite, thermal actiation, heavy metals, Cd(Ⅱ), precipitate reaction