[Spectroscopic characterization of heavy metal wastewater treatment by pyrite].

Treatment of acidic heavy metal wastewater by pyrite was studied by reflectance spectroscopy and absorption spectroscopy. The surface reaction in pyrite and the interaction between pyrite and heavy metal were investigated. The diffuse reflectance FTIR spectroscopy (DRIFTS) showed that the surface hydroxyls in pyrite reacted with heavy metal ion in the process of wastewater treatment, and furthermore, the phenomenon of the acidic wastewater driven to neutrality(pH 7) naturally after treatment was reasonably explained by analyzed carbonate in pyrite. The reflectance spectroscopy in visible region can be used to characterize the change of mineral particle and specific surface in this treatment process, and the reasons for the activity of pyrite increasing in repetitive use were explained. A process of adsorption-precipitation from Cr ( VI) to Cr3+ and to Cr(OH)3 was proved by absorption spectroscopy and XPS during the treatment of Cr(VI)-bearing wastewater by pyrite.