Effect of natural organic matter (NOM) on the removal efficiency of Hg(ii) by MoS₂: dependence on the Hg/MoS₂ ratio and NOM properties

Abstract

Mercury (Hg) contamination in groundwater poses significant environmental and health risks, necessitating effective remediation strategies. Recently, molybdenum disulfide (MoS2) nanosheets have emerged as a promising nanomaterial for the remediation of...

Crystalline Phase Regulates Microbial Methylation Potential of Mercury Bound to MoS2 Nanosheets: Implications for Safe Design of Mercury Removal Materials

“…4,5 A wide array of adsorbents (such as activated carbon, metal oxides, and metal sulfides) have been used, 6−8 while new adsorbents continue to emerge. 9,10 Transition-metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS 2 ), 11,12 molybdenum diselenide (MoSe 2 ), 13,14 tungsten disulfide (WS 2 ) and tungsten diselenide (WSe 2 ), 15 have been considered the next-generation adsorbents 16 and have shown great potential in Hg(II) removal from water. TMDs have lamellar structures with an inner layer of metal atoms (e.g., Mo, W) covalently bonded to two outer layers of S or Se atoms.…”

“…11 Moreover, removal of Hg(II) by MoS 2 from aqueous solutions not only involves adsorption, but also subsequent reduction, as the redox potential of the Hg 2+ /Hg 0 pair (0.845 V) is higher than the MoO 4 2− and SO 4 2− /MoS 2 pair (0.429 V). 12,17,22,23 It is noteworthy that two most common crystalline phases of MoS 2 �1T-MoS 2 (a metallic phase) and 2H-MoS 2 (a semiconductor)�exhibit different Hg(II) removal efficiencies, due to the stronger electron-transfer capability of the 1T phase. 24 An important consideration in designing effective TMDbased materials for mercury removal is the safe disposal of the spent materials, 25 as the accumulation of mercury on adsorbents can create Hg-rich hotspots that promote microbial methylation that produces methylmercury (MeHg), 26−28 a highly potent and bioaccumulative neurotoxin.…”

“…Mercury (Hg) is one of the most toxic heavy metals, and is labeled one of the “top ten chemicals of public health concern” by the World Health Organization (WHO) . Mercury in drinking water can damage the digestive, nervous and immune systems. , To date, adsorption has been the most commonly adopted and most reliable approach to remove mercury from water. , A wide array of adsorbents (such as activated carbon, metal oxides, and metal sulfides) have been used, − while new adsorbents continue to emerge. , Transition-metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS 2 ), , molybdenum diselenide (MoSe 2 ), , tungsten disulfide (WS 2 ) and tungsten diselenide (WSe 2 ), have been considered the next-generation adsorbents and have shown great potential in Hg­(II) removal from water. TMDs have lamellar structures with an inner layer of metal atoms (e.g., Mo, W) covalently bonded to two outer layers of S or Se atoms. − This structural feature maximizes the availability of binding sites of Hg­(II), allowing strong complexation of Hg via acid–base interactions. , MoS 2 nanosheets exhibit a high removal capacity (as much as 2506 mg g –1 ) and high selectivity in Hg­(II) removal from drinking water .…”

“…TMDs have lamellar structures with an inner layer of metal atoms (e.g., Mo, W) covalently bonded to two outer layers of S or Se atoms. − This structural feature maximizes the availability of binding sites of Hg­(II), allowing strong complexation of Hg via acid–base interactions. , MoS 2 nanosheets exhibit a high removal capacity (as much as 2506 mg g –1 ) and high selectivity in Hg­(II) removal from drinking water . Moreover, removal of Hg­(II) by MoS 2 from aqueous solutions not only involves adsorption, but also subsequent reduction, as the redox potential of the Hg 2+ /Hg 0 pair (0.845 V) is higher than the MoO 4 2– and SO 4 2– /MoS 2 pair (0.429 V). ,,, It is noteworthy that two most common crystalline phases of MoS 2 1T-MoS 2 (a metallic phase) and 2H-MoS 2 (a semiconductor)exhibit different Hg­(II) removal efficiencies, due to the stronger electron-transfer capability of the 1T phase …”