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.
This study was supported by Priority Research Centers Program (Grant No: 2014R1A6A1031189) through the National Research Foundation of Korea funded by the Ministry of Education in South Korea. The authors acknowledge with the thanks Deanship of Scientific Research (DSR) at King Abdulziz University, Jeddah, for technical and financial support.
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