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The surface hydroxyls in pyrite and slag were investigated, and the result showed that the hydroxyls in pyrite slag were induced by residual pyrite. The diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicated that the surface hydroxyls in pyrite and slag reacted with thallium ion in the process of wastewater treatment. The 3 550 cm(-1) peak and 3 402 cm(-1) peak weakened after pyrite and slag treatment, nevertheless the 3 550 cm(-1) peak lowered and shifted to higher frequencies by about 70 cm(-1) with slag treatment. The reflectance spectroscopy in visible region was used to characterize the change of particle and specific surface in these treatment process, and furthermore, the fact that the activity of both pyrite and slag increased in repetitive use was explained.

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.