High-performance photocatalytic degradation of neutral red over cobalt grafted-mesoporous silica under UV irradiation

Cobalt-grafted-mesoporous silica nanoparticles with the Si/Co molar ratio of 70 were synthesized by using sol–gel method (denoted as Co-MSN). Characterization of the Co-MSN was carried out by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), and N2 adsorption/desorption analysis. Photocatalytic activity of the Co-MSN sample was studied for removal of neutral red as one of the most widely used dye pollutants, in presence of H2O2 and UV irradiation. In this regard, effect of various influencing parameters such as pH, Co content, dye concentration, amount of oxidant, and presence/absence of UV irradiation were investigated. It was found that incorporation of the Co2+ ions into the mesoporous silica nanostructure significantly improves the photocatalytic degradation of neutral red. Under the optimized conditions including 0.3 mmol of H2O2 (as an oxidant), catalyst dosage of 0.075 mg, initial dye concentration of 0.08 mM, and UV irradiation (32 W, 254 nm), up to 81% of neutral red was degraded at room temperature for 220 min.