Enhanced Removal of Methyl Violet Dye from Aqueous Solution by a Novel Co3O4@SiO2@TiO2-Ag Heterogeneous Semiconductor

Background: This research proposes the application of a novel photocatalyst including Co3O4@SiO2@TiO2-Ag nanocomposite with highly photocatalytic stability and core-shell structure for the removal of toxic methyl violet from aqueous solution. Objective: The removal of toxic dyes and organic contaminants from water is an outstanding research area among the scientists. Methyl violet is a toxic cationic pollutant that has a disruptive influence on humans. In this research, with an aim to remove methyl violet from the wastewater, we developed a new photocatalyst including Co3O4@SiO2@TiO2-Ag nanocomposite as an ecofriendly and low-cost nanostructure with high photocatalytic activity in order to reduce the risks of this pollutant from aqueous media. Methods: The Co3O4@SiO2@TiO2-Ag nanostructure was prepared via hydrothermal and sol-gel methods and the structure elucidation of the prepared photocatalyst was analyzed by different spectroscopy techniques, including XRD, FT-IR, FE-SEM, TEM, VSM and EDX. Results: Photodegradation of methyl violet in the presence of different structures showed that Co3O4@SiO2@TiO2-Ag possesses superior photocatalytic activity (about 98% decomposed after 40 min) compared to the previous shells and pure Co3O4 NPs. Loadings of SiO2@TiO2-Ag nanocomposite over the Co3O4 surface led to the reduction in the bandgap energy of visible light and improvement in the photocatalytic activity of Methyl Violet dye f o r the aqueous phase decomposition. Conclusion: The remarkable benefits of this nanocomposite are high photocatalytic efficiency in the degradation of methyl violet (almost 100 % within 1 h), easy magnetic separation, low cost, and high chemical stability. The collected results demonstrated that the rate of degradation increased by increasing the irradiation time, while the rate of degradation decreased with increasing dye concentration.