Two-dimensional MXene and Molybdenum Disulphide (MoS2) for the Removal of Hexavalent Chromium Cr(VI) from Water

Abstract

Chromium is one of the most typical heavy metal pollutants that is genotoxic, carcinogenic and accumulates in plant and animal bodies. The use of emerging materials for efficient removal of chromium is in high demand. MXene and MoS2 were employed in this investigation to extract hexavalent chromium (Cr(VI)). The pseudo second order kinetic model described the adsorption of Cr(VI) on MXene and MoS2. In the meanwhile, the Freundlich and Langmuir Isotherm models best fitted MXene and MoS2, respectively. The greater number of surfaceactive sites in MoS2 led to a higher removal efficiency for Cr(VI) as compared to MXene. At 298K, the highest adsorption capacities of MXene and MoS2 for Cr(VI) were 59.805 mg/g and 113.71 mg/g, respectively. Thermodynamic investigations of both materials exhibited that the adsorption process was endothermic and spontaneous. The effect of coexisting ions was also investigated in the study that involves coexisting anions like PO4 3- , HCO3 2- , Cland coexisting cations such as Ca2+, Mg2+, Na1+. MXene showed a decrease in removal percentage up to 70% after fifth cycle whereas the decrease in percentage removal reached 79% in case of MoS2 after fifth cycle. According to the findings, it can be inferred that these developed materials have the advantages of simplicity and effortless operation like adsorption for reducing heavy metal pollution.