Enhancing visible-light-driven NO oxidation through molecular‐level insights of dye-loaded sea sands

Natural minerals, abundant and easily obtained through simple physical processing, offer a cost-effective and environmentally friendly solution for dyeing wastewater disposal and air pollution treatment. This study investigates the photocatalytic removal of NO using natural different types of dyes, loaded on natural sand, under visible light illumination. By examining various coating concentrations of dyes and sand weights, we discovered that sand loaded with Rhodamine B (RhB) exhibits high activity for the photo-oxidation of NO. A combination results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analyses confirm the presence of SiO2, CaCO3, Al2O3 and iron oxides as the main components of the sand. Furthermore, studying RhB-loaded individual components reveals that CaCO3 plays a crucial role in enhancing the NO removal rate. Experimental results and theoretical calculations demonstrate the establishment of a directional charge transfer channel from CaCO3 to RhB, facilitating the adsorption and activation of molecular NO and O2. This work not only promotes the utilization of natural mineral resources but also enriches the fields of environmental photochemistry and semiconductor photocatalysis. Graphical abstract: [Figure not available: see fulltext.].