Enhancing sonocatalytic dye pollutant degradation using MoS2/RGO nanocomposites: An optimization study

This research focuses on the synthesis of MoS2/RGO nanocomposite, which serves as an efficient sonocatalyst, using a simple one-step hydrothermal method. The MoS2/RGO was characterized through various techniques including X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), Raman spectrometry, diffuse reflectance spectroscopy (DRS), and Fourier transform infrared (FTIR) spectroscopy. A comprehensive investigation into the sonocatalytic degradation efficiency of methylene blue (MB) dye was conducted under different conditions using design of experiment (DOE) approach. Response surface methodology (RSM) based on central composite design (CCD) was employed to optimize the key operational parameters, namely initial dye concentration, catalyst dosage, ultrasonic power, sonication time, and pH. The reliability of the model was assessed using analysis of variance. Under the optimal conditions of 20 mg/L initial MB concentration, catalyst dosage of 0.5 g/L, 67 W ultrasonic power, sonication time of 28 min, and pH of 7, a remarkable MB degradation efficiency of 99% was achieved. Hydroxyl radical ((OH)-O-center dot) were identified as the main radical species in the sonoluminescence reaction. Additionally, the sonocatalyst demonstrated an excellent reusability, with approximately 95% retention of the degradation efficiency observed over five sonocatalysis cycles.