Sustainable Design of Molybdenum Disulfide Nanocomposites for Silver Recovery

Recent increasing industrial demand for precious metals suggests recycling and regeneration as a means to decrease the energy consumption and cost associated with precious metal use. Molybdenum disulfide (MoS2) nanosheets have demonstrated selective and efficient adsorption potential toward heavy metals, but their application in recovering precious metals has not been reported. In this study, we affix MoS2 onto platforms to increase the sustainability and practicality of silver (used as a precious metal model) recovery from wastes, with the optimal design determined by effectiveness, sustainability, and scalability criteria. MoS2 was synthesized on three robust platforms─sand particles, alumina beads, and PTFE beads─using bottom-up solvothermal methods. While a stable homogeneous molybdenum sulfides and oxides layer was formed over sand and alumina, PTFE beads were only partially coated. Silver was adsorbed onto MoS2@sand and MoS2@alumina at similar rates, but less was adsorbed on MoS2@PTFE. Recovery of silver from the nanocomposites was examined, and a thiourea and EDTA mixture was found to be the best desorbing solution, allowing over 80% silver recovery from MoS2@alumina. Our study indicates that among the platforms tested, alumina beads are the optimal MoS2 platform for precious metal recovery applications, allowing high adsorption and recovery rates with minimal Mo leaching. Overall, this study advances the utility and practical design of MoS2-based nanocomposites in water-treatment schemes, particularly for viable use in commercial aqueous metal recovery.