Selective adsorption of organic dyes from aqueous environment using fermented maize extract-enhanced graphene oxide-durian shell derived activated carbon composite

A secure aquatic environment is essential for both aquatic and terrestrial life. However, rising populations and the industrial revolution have had a significant impact on the quality of the water environment. Despite the implementation of strong and adapted environmental policies for water treatment worldwide, the issue of organic dyes in wastewater remains challenging. Thus, this study aimed to develop an efficient, cost-effective, and sustainable material to treat methylene blue (MB) in an aqueous environment. In this research, maize extract solution (MES) was utilized as a green cross-linker to induce precipitation, conjugation, and enhance the adsorption performance of graphene oxide (GO) cross-linked with durian shell activated carbon (DSAC), resulting in the formation of a GO@DSAC composite. The composite was investigated for its adsorptive performance toward MB in aqueous media. The physicochemical characterization demonstrated that the cross-linking method significantly influenced the porous structure and surface chemistry of GO@DSAC. BET analysis revealed that the GO@DSAC exhibited dominant mesopores with a surface area of 803.67 m²/g. EDX and XPS measurements confirmed the successful cross-linking of GO with DSAC. The adsorption experiments were well described by the Harkin-Jura model and they followed pseudo-second order kinetics. The maximum adsorption capacity reached 666.67 mg/g at 318 K. Thermodynamic evaluation indicated a spontaneous, feasible, and endothermic in nature. Regenerability and reusability investigations demonstrated that the GO@DSAC composite could be reused for up to 10 desorption-adsorption cycles with a removal efficiency of 81.78%. The selective adsorptive performance of GO@DSAC was examined in a binary system containing Rhodamine B (RhB) and methylene orange (MO). The results showed a separation efficiency (α) of 98.89% for MB/MO and 93.66% for MB/RhB mixtures, underscoring outstanding separation capabilities of the GO@DSAC composite. Overall, the GO@DSAC composite displayed promising potential for the effective removal of cationic dyes from wastewater.