Performance and characterization of calcined colloidal pyrite used for copper removal from aqueous solutions in a fixed bed column

The aim of this study was to investigate the capacity and mechanism of a novel and cost-effective sorbent for copper (Cu) removal and recovery from wastewater. Calcined colloidal pyrite (CCPy) was prepared by calcining natural colloidal pyrite mineral in a N-2 atmosphere. Cu2+ removal from aqueous solutions by using iron sulfides was investigated with fixed-bed column experiments. Results show that CCPy was much more efficient in Cu2+ removal than other three iron sulfide sorbents (natural pyrite, colloidal pyrite, and pyrrhotite). When the influent Cu2+ concentration was 1.56 mmol/L and Cu2+ breakthrough concentration was 0.0078 mmol/L, the throughput volume of the CCPy column was up to 1672 bed volumes (BV); the sorption amount at breakthrough was 84 mg Cu/g CCPy. The maximum Cu content in the used CCPy sorbent was up to 20%, which is much higher than the grades of industrial Cu ore (0.4-2.8%), indicating that CCPy can be used as an effective sorbent for the recovery of Cu2+ from wastewater. Copper specification analysis, X-ray diffraction (XRD), and transmission electron microscopy (TEM) show that Cu removal by CCPy was mainly due to the formation of covellite on the CCPy's surface. The CCPy sorbent has advantages over chemical precipitation and other sorbents due to the recovery of Cu from wastewater, cheap raw material for manufacturing this sorbent, and prevention of hazardous sludge generation. (C) 2014 Elsevier B.V. All rights reserved.