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

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.

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.

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.

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.

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.