Amorphous molybdenum sulfide mediated EDTA with multiple active sites to boost heavy metal ions removal

The rational design of strong affinity adsorbents for heavy metal ions removal remains a critical challenge for water treatment.In this study,amorphous molybdenum sulfide composites(EDTA-MoSx(x=2,3))were fabricated via a facile hydrothermal method mediated by EDTA,which was applied to heavy metal ions(Cu^(2+),Cd^(2+),Pb^(2+),Zn^(2+)and Ni^(2+))removal from aqueous solutions.A case study for Cu^(2+)ions showed that the adsorption capacity of EDTA-MoSx(x=2,3)was superior to crystalline phase MoS2 at pH 6.0 with an initial concentration of 200 mg/L.Adsorption mechanisms of different sulfide groups and—COOH of EDTA-MoSx(x=2,3)were verified systematically via a series of experiments,characterizations,and density functional theory(DFT)calculations.Both bridging S_(2)^(2-)and—COOH covalently bonded with Cu^(2+)ions were ascribed to the critical factors for this enhanced removal efficiency on the surface of EDTA-MoSx(x=2,3).This work offers a new method to enhance the adsorption performance of molybdenum sulfide-based materials by controlling crystallinity mediated with an organic complex small molecule.