Simple and sustainable route for large scale fabrication of few layered molybdenum disulfide sheets towards superior adsorption of the hazardous organic pollutant

The exfoliation of a bulk material to a few layer thickness without using expensive exfoliating agents and chemicals is essential for practical applications in various fields. In this study, a simple and scalable mechanical milling process was used to improve the surface and adsorption characteristics of bulk MoS₂ through a reduction of the layered thickness to a few layers as well as a significant increase in the surface area of the MoS₂. The resulting and optimized MoS₂ were characterized using various spectroscopic and microscopic techniques, as well as nitrogen adsorption–desorption isotherm analysis. The adsorption property of the exfoliated MoS₂ for crystal violet dye (CV) was assessed. The results showed that prolonged (60 h) milled MoS₂ had the highest adsorptive removal of CV. The adsorption mechanism of CV onto the MoS₂ nanosheets was investigated in terms of the adsorption kinetics, thermodynamics, and isotherms. The optimal removal of CV was observed at pH 10 and a pseudo-second order kinetic model was best fitted to the adsorption dynamic data. The adsorption of CV onto the MoS₂ nanosheets was endothermic and the adsorption equilibrium data followed the Langmuir isotherm model. The maximum monolayer adsorption capacity of the MoS₂ nanosheets increased from 144.92 to 161.29 mg g⁻¹ with increasing solution temperature from 30 to 50 °C. These results showed that ball milling is an efficient method to exfoliate bulk MoS₂ to MoS₂ nanosheets and the exfoliated nanosheets could be used as an efficient adsorbent for the scavenging of organic pollutants.