Reusable and highly stable MoS2 nanosheets for photocatalytic, sonocatalytic and thermocatalytic degradation of organic dyes: Comparative study

The presence of emerging pollutants in industrial wastewater is a global problem and requires appropriate treatment techniques. Herein, reusable, stable and highly efficient MoS2 nanosheets are prepared via a one-step hydrothermal process. The prepared MoS2 nanosheets are proposed as an environmentally friendly catalyst for treating polluted waters. The comparative effectiveness of the photocatalytic, sonocatalytic, and thermocatalytic degradation processes for the elimination of Rhodamine B (RhB) is investigated. The morphology, composition, and optical properties of the prepared MoS2 nanostructure are characterized using different tools. The vertically aligned MoS2 nanosheets are confirmed by TEM. Moreover, the D-spacing of the nanosheets and corresponding band gap are found to be 0.6 nm and 1.19 eV, respectively. The remarkable catalytic degradation performance of MoS2 nanosheets via the three advanced oxidation processes (AOPs) is attributable to its two-dimensional stacked layers. By using various active species traps, it is proven that the superoxide anion is the major reactive species in the photocatalytic and sonocatalytic degradation of RhB dye. In the case of the thermocatalytic process, holes have the main role. Maximum catalytic efficiency over MoS2 nanosheets is observed with removal percentages of 100 %, 100 % and 80 % after 15 min for photocatalytic, sonocatalytic, and thermocatalytic degradation, respectively. Moreover, the dye degradation and mineralization are confirmed by high COD removal. The MoS2 nanosheets showed high chemical stability after recycling. Consequently, these hydrothermally prepared MoS2 nanosheets can be considered as a promising catalyst for the degradation of emerging pollutants from an aqueous solution.