Efficient and selective removal of Hg(II) from water using recyclable hierarchical MoS/FeO nanocomposites.

Developing practical and cost-effective adsorbents with satisfactory mercury (Hg) remediation capability is indispensable for aquatic environment safety and public health. Herein, a recyclable hierarchical MoS/FeO nanocomposite (by in-situ growth of MoS nanosheets on the surface of FeO nanospheres) is presented for the selective removal of Hg(II) from aquatic samples. It exhibited high adsorption capacity (∼1923.5 mg g ), fast kinetics (k ∼ 0.56 mg g  min), broad working pH range (2-11), excellent selectivity (K > 1.0 × 10 mL g ), and great reusability (removal efficiency > 90% after 20 cycles). In particular, removal efficiencies of up to ∼97% for different Hg(II) concentrations (10-1000 μg L ) in natural water and industrial effluents confirmed the practicability of MoS/FeO. The possible mechanism for effective Hg(II) removal was discussed by a series of characterization analyses, which was attributed to the alteration of the MoS structure and the surface coordination of Hg-S. The accessibility of surface sulfur sites and the diffusion of Hg(II) in the solid-liquid system were enhanced due to the advantage of the expanded interlayer spacing (0.96 nm) and the hierarchical structure. This study suggests that MoS/FeO is a promising material for Hg(II) removal in actual scenarios and provides a feasible approach by rationally constructing hierarchical structures to promote the practical applications of MoS in sustainable water treatments.