Hierarchical Microspheres of MoS₂ Nanosheets: Efficient and Regenerative Adsorbent for Removal of Water-Soluble Dyes

Abstract

This study demonstrates fast and efficient removal of dyes from the wastewater using nanostructural MoS 2 as a regenerative adsorbent. The hierarchical microspheres of MoS 2 nanosheets were prepared by a one-step facile and scalable hydrothermal route using polyethylene glycol as a templating material. Chemical and morphological features of hierarchical microspheres of MoS 2 nanosheets were examined by XPS, FTIR, XRD, FESEM, and HRTEM. The adsorption of a series of organic dyes using MoS 2 nanosheets was systematically investigated. The kinetic study illustrated that adsorption of methylene blue dye onto the MoS 2 nanosheets followed the pseudo-second-order model. The adsorption isotherm at the equilibrium was supported by the Freundlich model. The hierarchical microspheres of MoS 2 nanosheets showed adsorption capacity as high as 297, 204, 216, 183, 146 mg g –1 for methylene blue, malachite green, rhodamine 6G, fuchsin acid, and congo red dyes, respectively. The high adsorption capacity was attributed to the hierarchical arrangement of MoS 2 nanosheets in the microscopic spheres, where dye molecules have very fast accessibility. Importantly, the hierarchical microspheres of MoS 2 nanosheets can be efficiently regenerated and reused for the dye adsorption of subsequent batch without compromising the adsorption capacity.