The performance of mordenite-dispersed and stabilized ferrous sulfide composites for the removal of Cr(VI) from aqueous solutions

Abstract

In this study, a composite material (FeS-Mor) of nano ferrous sulfide (FeS) and mordenite was prepared by coprecipitation method using mordenite as a stabilizer to prevent the aggregation of FeS to achieve the purpose of efficient removal of chromium from water. Experimental results revealed that the optimum pH for Cr(VI) removal was ∼ 2 with a removal capacity of 199.0 mg/g and efficiency of 99.5 % at 303 K. Common co-existing cations of Na+, Ca2+ and K+ promoted the removal efficiency, while Mg2+ inhibited the removal of Cr(VI). While Common anions of SO42−, CO32−, Cl− and NO3− inhibited chromium removal. The pseudo-second-order kinetics model fitted the kinetic removal of Cr(VI) onto FeS-Mor composites best under absent/present co-existing cations, indicating that chemical reduction and complexation dominated the removal process. The thermodynamic results were best described with the Freundlich model and showed an endothermic process of Cr(VI) removal. The FeS-Mor composites with FeS:Mor mass ratio in the range of 1:1–1:2 exhibited the best performance in removal efficiency and reusability. These results reveal that introducing mordenite to develop an efficient FeS-based nanocomposite system can significantly improve the performance of chromium remediation from aqueous solutions.