Synthesis of Graphene Oxide/Silica/Carbon Nanotubes Composite for Removal of Dyes from Wastewater

The recent interest in adsorption of pollutants on nanomaterials has been gaining widespread attention especially in the utilization of nanocarbon based composite materials. Herein, graphene oxide/silica/single-wall carbon nanotubes (GO/SiO₂/SWCNTs) composite was successfully prepared by a hydrothermal method for the adsorption of Congo red (CR) dye from synthetic wastewater. The nanocomposite morphology was characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), and Energy-dispersive X-ray spectroscopy (EDX). The present study focuses on the adsorption performance of CR dye from aqueous solution on GO/SiO₂/SWCNTs composite in terms of kinetics, isotherm, thermodynamics studies and optimization of factors such as pH, temperature, concentration and adsorption time. The results showed that a higher adsorption of CR was observed onto GO/SiO₂/SWCNT composite at pH 3.0 as compared to that with SiO₂ and SWCNT. Similarly, the maximum adsorption capacity of 456.15 mg g^-1 was achieved at optimum temperature 20 °C, time (330 min) and 300 mg L^-1 CR solution concentration. The dye adsorption on the nanocomposite was found to be obeying pseudo-second-order rate equation. Thermodynamic parameters showed that the adsorption of CR dye was spontaneous in nature.