Rational construction of MoSx via defect engineering for efficient removal of mercury ions from aqueous solution

Abstract

Mercury ions (Hg2+) are one of the most physiologically toxic heavy metal ions in water. Developing adsorbents for separating and removing mercury ions from aquatic systems has important environmental and social significance. Owing to the hard-soft-acid-base interaction between mercury and sulfur (S) atoms, two-dimensional layered MoS2 holds great promise in capture physiologically toxic Hg2+ from water, but most S atoms are located inside the bulk MoS2, hindering the effective contact with mercury. Defects engineering is considered as an effective way to adjust the structure and achieve superior performance of MoS2. However, reasonable and fine defect modulation to enhance the mercury adsorption performance remains a challenging task. Herein, we reported that molybdenum sulfide with Mo-vacancy structure (MV-MoSx) was fabricated via hydrothermal method and employed to uptake Hg2+. The results showed that this defect type significantly increased the concentration of Mo stripping defects, exposed more active S atoms, and provided MoSx with excellent adsorption performance in adsorption capacity, adsorption kinetics, distribution coefficient, selectivity and so on. In particular, MV-MoSx demonstrates a substantial actual adsorption capacity for mercury, reaching as high as 3723.3 mg/g, which is in close proximity to its theoretical adsorption capacity of 3945.95 mg/g. More importantly, a functionalized composite aerogel system based on MV-MoSx was constructed, which successfully reduced the concentration of Hg2+ solution below the concentration permitted by drinking water standards. Our study not only provide a theoretical basis for the design of novel defect engineering, but also expand the application of transition metal sulfides in the enrichment and separation of heavy metal ions.