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

This study demonstrates fast and efficient removal of dyes from the wastewater using nanostructural MoS2 as a regenerative adsorbent. The hierarchical microspheres of MoS2 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 MoS2 nanosheets were examined by XPS, FTIR, XRD, FESEM, and HRTEM. The adsorption of a series of organic dyes using MoS2 nanosheets was systematically investigated. The kinetic study illustrated that adsorption of methylene blue dye onto the MoS2 nanosheets followed the pseudo-second-order model. The adsorption isotherm at the equilibrium was supported by the Freundlich model. The hierarchical microspheres of MoS2 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 MoS2 nanosheets in the microscopic spheres, where dye molecules have very fast accessibility. Importantly, the hierarchical microspheres of MoS2 nanosheets can be efficiently regenerated and reused for the dye adsorption of subsequent batch-without compromising the adsorption capacity.