Fabrication of Ca-doped TiO2 for enhanced methylene blue degradation under UV-Vis irradiation

Research continues to improve the dye degradation performance of TiO 2 nanoparticles (NPs) through doping, tailoring, or modifying the lattice structure. A series of Ca–TiO 2 (Ca ions 0.5–2.0 wt%) photocatalysts prepared by wet impregnation method were studied for methylene blue (MB) degradation under UV-Vis irradiation, using different factors, including contact time, pH, initial dye concentration, and dosages. The photocatalyst samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Characterization results revealed the successful doping of Ca ion on the TiO 2 surface, and Ti, O, and Ca were identified by EDX analysis as being present in the Ca-doped TiO 2 sample. Calcium improved titania's charge separation capability, favoring the formation of more hydroxyl radicals during irradiation. Another important effect of Ca is the lowered bandgap energy of TiO 2 , which enhances the light absorption capacity into the visible regions. The photocatalytic performance varied with calcium ions content in the prepared catalysts, and a moderate amount showed the best activity. 1 wt% Ca–TiO 2 exhibited a maximum MB degradation of 79.65 % with TOC removal of 52.36 % and followed the pseudo-first-order reactions kinetics with a rate constant of 0.0087 min −1 . Notably, both the degradation performance and rate constant of 1 wt% Ca-TiO 2 catalysts were much superior to pure TiO 2 under the same reaction conditions. This finding suggests that Ca-TiO 2 NPs could be a highly effective photocatalyst for the ecologically benign degradation of color compounds in textile wastewater. • Ca-doped TiO 2 photocatalysts were synthesized by wet impregnation method. • Characterization confirmed the incorporation of Ca ions into TiO 2 matrix. • Ca ions dopant successfully decreased the bandgap energy. • Maximum 79.65 % MB degradation was obtained for 1.0 wt% Ca ions under UV-Vis irradiation within 3 h. • Ca-doped TiO 2 showed much higher dye degradation activity than pure TiO 2 .