Biochar derived from yerba-mate (Ilex paraguariensis) as an alternative TiO2 support for enhancement of photocatalytic activity toward Rhodamine-B degradation in water

In this work, a novel biochar-based support derived from Ilex paraguariensis was produced and impregnated with TiO2 for use as a photocatalyst to degrade Rhodamine-B (RhB) in water. The sample was characterized by X-ray diffractometry, Fourier-transformed infrared spectroscopy, scanning electron microscopy, diffuse reflectance spectroscopy, and N2 adsorption-desorption isotherms. The TiO2/biochar composite presented superior photoactivity compared to TiO2 alone, achieving 96% decolorization and 75% TOC removal. These remarkable results can be associated with a combination of properties such as lower band-gap energy (3.11 eV), higher pore size (46 nm), and surface area (67.36 m2 g−1) values, as well as uniform distribution of TiO2 on the support surface. Furthermore, the superoxide radicals (O2•-) significantly contributed to degrading RhB. In addition, a possible reaction pathway involving the RhB degradation was proposed. Overall, the produced material in this work was highly effective to degrade RhB in aqueous medium under UV light, thus proving to be a promising photocatalyst for remediation of contaminant molecules.