Synthesis of calcium silicate hydrate from chicken eggshells and combined joint effect with nervous system insecticides

The world will produce 90 million tons of chicken eggs in 2030. As eggshell represents 11%, about 10 million tons of waste shells accumulate in the environment, which causes a hazard to human health. Recycling this waste into value-added products requires adequate strategies. Herein, amorphous calcium silicate hydrate (ECSH) has been synthesized via sol-gel method by utilizing chicken eggshells as an alternative source of calcium. ECSH was characterized using the wide-angle X-ray diffraction (XRD) pattern, Fourier transform-infrared spectroscopy (FT-IR), N2 adsorption/desorption isotherms, and field-emission scanning electron microscopy (FE-SEM). The insecticidal activity of ECSH and nervous system insecticides (methomyl and chlorpyrifos) was evaluated against Spodoptera littoralis. Methomyl and chlorpyrifos displayed high acute toxic effects with LC25 of 158.0 and 98.14 ppm and LC50 of 438.25 and 256.68 ppm, respectively. The combination of ECSH with methomyl and chlorpyrifos increased the insecticidal activity and reduced the applied amount of such toxic insecticides.