Mutual effects behind the simultaneous removal of toxic metals and cationic dyes by interlayer-expanded MoS2 nanosheets

Simultaneous removal of coexisting metals and dyes from industrial wastewaters is challenging, and the mutual effects behind the co-adsorption of these pollutants remain unclear. Herein, interlayer-expanded MoS2 (IE-MoS2) nanosheets prepared by a one-pot simple and scalable method were tested to simultaneously remove toxic metals and cationic dyes. The adsorption capacities of IE-MoS2 nanosheets were 499, 423, 500, 355, and 276 mg/g for Pb(II), Cu(II), methylene blue, malachite green, and rhodamine B, respectively, in a mono-contaminant system. Interestingly, the sequestration amount of Pb(II) was dependent on the concentrations of dyes in the binary Pb(II)-dye systems, while uptake of cationic dyes was almost not influenced by coexisting Pb(II). The simultaneous adsorption mechanism was further confirmed by spectroscopic methods. The IE-MoS2 nanosheets were easily regenerated and reused for six adsorption-desorption cycles without structure destruction, thus avoiding the potential hazards of nanomaterial to the ecosphere. More interestingly, high-efficiency uptake of Pb(II) from intentionally contaminated natural water and model textile effluent was obtained by using a column filled with IE-MoS2 nanosheets. In summary, IE-MoS2 nanosheets with facile and scalable synthesis method, efficient adsorption performance, and excellent reusability showed potential promise for the integrative treatment of complex wastewater bearing both metals and organic pollutants.