Eggshell recycling for fabrication of Pd@CaO, characterization and high-performance solar photocatalytic activity.

Recycling of waste materials into useful products is a promising strategy for environmental protection. Eggshell is one of the globally produced huge wastes. In this work, calcium oxide (CaO) nanoparticles were recycled via calcination of chicken eggshells at 1100 °C for 2 h. A novel nanocomposite, made of loading palladium nanoparticles on calcium oxide surface (Pd@CaO), is successfully fabricated through solid-solid interaction. The materials were characterized using different physicochemical techniques: Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), photoluminescence (PL) analysis, ultra-high resolution field emission scanning electron microscope (FE-SEM), transmittance electron microscope (TEM), and X-ray diffraction (XRD). The study sheds light on the ability of the materials to be used for detoxification of crystal violet dye as pollutant model under solar irradiation. The effects of operational conditions, such as catalyst mass, initial dye concentration, pH, and illumination time, have been tested. The optimum conditions for crystal violet photocatalytic degradation in the presence of Pd@CaO were mild conditions. Control experiments studied the effect of sunlight in the absence of the catalyst, and the effect of the catalyst in the absence of sunlight does not provide the significant removal exhibited in the presence of catalyst under solar irradiation.