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 (Cu2+, Cd2+, Pb2+, Zn2+ and Ni2+) removal from aqueous solutions. A case study for Cu2+ 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 single -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 single -COOH covalently bonded with Cu2+ 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. (C) 2021 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

The rational design of strong affinity adsorbents for heavy metal ions remains a challenge in water treatment. In this study, amorphous molybdenum sulfide composites (EDTA-MoSx (x = 2, 3)) were successfully synthesized and showed superior adsorption capacity for Cu2+ ions, attributed to the covalent bonding of S-2(2)- and -COOH groups with the ions. The work offers a new method to enhance adsorption performance by controlling crystallinity with organic complexes.