Sustainable Approach in Palm Oil Industry – Green Synthesis of Palm Oil Mill Effluent Based Graphene Sand Composite (P-GSC) for Aerobic Palm Oil Mill Effluent Treatment

Graphene sand composite (GSC), sand media coated with graphene, possess higher adsorption capacity for wastewater treatment compared to conventional activated carbon (AC). However, large-scale synthesis of GSC due to costly carbonaceous source appears as a great challenge towards commercial application. Palm oil mill effluent (POME), which abundantly discharged from the palm oil industry, appears to be a potentially low cost carbonaceous source for the synthesis of GSC. This study presented a green chemistry approach by utilizing the POME as carbonaceous source coated on the different particle size of river sand in synthesizing POME-based GSC (P-GSC). Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray (EDX), and X-ray Diffraction (XRD) analysis indicated the successful graphinization of POME coated onto the river sand surface. Adsorption studies – batch column study and batch equilibrium study showed that small size P-GSC (0.30 – 0.60 mm) had the best performance in removing chemical oxygen demand (COD), colour, turbidity, and total dissolved solids (TDS) from diluted aerobic POME up to 94.7%, 92.3%, 83.3%, and 51.5%, respectively. This could be attributed to its larger surface area that provides more active sites for adsorption. Equilibrium sorption data of small size P-GSC was wellfitted to the Freundlich model and its associated adsorption kinetic could be described by Pseudo First Order model. The concept of sustainable waste-to-treat-waste has been proven throughout this study, where POME can be utilized to produce high performance P-GSC that can be used to treat aerobic POME.