Highly efficient capacitive removal of Cd2+ over MoS2-Carbon framework composite material in desulphurisation wastewater from coal-fired power plants

Cadmium (Cd 2+ ) is the main toxic heavy metal in desulphurisation wastewater for coal-fired power plants. Here, a novel carbon skeleton/molybdenum disulphide composite material (MoS 2 /AC) with expanded layer spacing was synthetized in one step for Cd 2+ removal through the capacitive deionization method. As the results showed, the Cd 2+ removal capacity of the MoS 2 /AC cell was 22.15 mg g −1 , and the concentration of Cd 2+ in the simulated wastewater was effectively reduced from 10 ppm to <0.1 ppm. According to the characterisation, the layer spacing of MoS 2 nanosheets in MoS 2 /AC increased by 58.06% compared with the original commercial MoS 2 , which could provide more active sites for Cd 2+ adsorption. Moreover, the XPS results showed that electrosorption and complexation on the surface of MoS 2 /AC were the main routes for Cd 2+ removal, especially the complexation between Cd 2+ and metal-sulphur. In addition, the selective adsorption efficiency of MoS 2 /AC was more than 98% under the coexistence of other ions, such as Na + , Mg 2+ , and Ca 2+ . The regenerated MoS 2 /AC also had a high adsorption capacity for Cd 2+ even after 5 cycles. The MoS 2 /AC material also exhibited excellent removal capability for heavy metal ions in the actual desulphurisation wastewater from coal-fired power plants (<1 ppb). The results indicated that MoS 2 /AC may be a prospective material for heavy metal ion removal from wastewater.