Ternary tin-doped titanium dioxide/calcium oxide (Sn-TiO/CaO) composite as a photocatalyst for efficient removal of toxic dyes.

In this study, a novel environmentally friendly route was explored for the synthesis of a tin-doped titanium dioxide/calcium oxide (Sn-TiO/CaO) composite using eggshell as a ternary photocatalyst. The composite was prepared a simple hydrothermal method, resulting in a unique material with potential applications in photocatalysis. The prepared photocatalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis/diffuse reflectance spectroscopy, scanning electron microscopy, X-ray fluorescence, and the Brunauer-Emmett-Teller techniques. At the same time, the Sn-TiO/CaO composite shows excellent degradation activity for toxic dyes. The degradation efficiencies for alizarin red, bromophenol blue, methylene blue, malachite green, and methyl red are 68.38%, 62.39%, 76.81%, 86.93%, and 17.52%, respectively, under ultraviolet light irradiation for 35 min at pH = 3. In addition, the best photocatalytic degradation efficiency for zero charge (pH 7) and basic pH is for AR 98.21% and 68.38%, MR 33.01% and 17.52%, BPB 73.17% and 17.52%, MB 72.32% and 76.81%, and MG 85.59% and 86.93%, respectively, under UV light irradiation for 35 min. The increase in photocatalytic activity of the ternary photocatalyst is accredited to the enhancement of electron-hole pair separation. Simultaneous photodegradation and photoreduction of organic dyes show that ternary photocatalysts could be used in real wastewater applications.