Adsorption properties of graphene oxide/SiO₂ composites for Cd(Ⅱ)

The graphene oxide/SiO₂ composite (GO/SiO₂) was fabricated using graphene oxide (GO), ethylsilicate (TEOS) as the raw material, oxygen polyoxyethylene-polypropylene-polyoxyethylene (P123) as the surfactant. Through a static test, different experimental parameters such as solution pH, dosing, adsorption time and initial concentration were examined to investigate their effects on adsorption of cadmium by GO/SiO₂. The GO/SiO₂ composite was investigated by FTIR, XRD, SEM and EDS. The experimental results show that the optimal pH, dosing, adsorption time is 8.5, 0.25 g/L, and 100 min, respectively. The equilibrium data fit well with the pseudo-second-order model(R² ≈1) and Freundlich model(R² ≈1). XRD indicate that SiO₂ has been successfully combined with GO. FTIR and SEM indicate that GO/SiO₂ structure itself keeps unchanged, and the GO/SiO₂ has good adsorption effect on Cd(Ⅱ), in which ionexchange of —OH and —COOH play a major role, with the assistant of complexation reaction of Si—OH in the adsorption.