Textile wastewater represents one of the major sources of water pollution worldwide due to its high content of organic compounds, surfactants, and, most notably, synthetic dyes. These molecules, characterized by high chemical stability and low biodegradability, are responsible for the persistent coloration of the effluents and may cause toxic and ecotoxicological effects on aquatic ecosystems. Therefore, the efficient removal of dyes from textile effluents remains a critical environmental and technological challenge. Following this purpose, this Master Thesis work investigated the degradation of textile dyes exploiting photocatalysis and photosonocatalysis. Among different photocatalysts, nanoparticles (NPs) of ZnO capped with oleic acid (Ol-ZnO) were chosen because of their good photocatalytic activity, non-toxicity and low price.