Efficient removal of Cr(VI) from aqueous solution by natural pyrite/rhodochrosite derived materials: Performance, kinetic and mechanism

Abstract In this work, pyrite/rhodochrosite (PyxRhy) composite synthesized from natural pyrite and rhodochrosite to remediate Cr(VI) containing wastewater was systematically investigated and evaluated. Results show that pyrite/rhodochrosite (1:1) showed the best Cr(VI) removal performance. XRD showed that emergence of MnS and pyrrhotite contributed to a significant increasing Cr(VI) reduction rate. The estimated maximum adsorption capacity was 95.58 mg/g at pH value of 6, temperature of 303.15 k, which was larger than other iron and manganese-based materials. Additionally, thermodynamic study illuminated that Cr(VI) removal by Py1Rh1 was a spontaneous and endothermic process. Taffel curve and EIS result presented higher corrosion current and lower electrical resistance for Py1Rh1, respectively, which was more favorable for the electron transfer. The surface cyclic regeneration of Fe(II) and Mn(II) provided long-term electron transfer to the Cr(VI) reduction. Our results demonstrated the great potentials of natural pyrite and rhodochrosite synthetic materials in the remediation of Cr(VI) polluted water.