Sustainable Synthesis of Graphene Sand Composite from Waste Cooking Oil for Dye Removal

Waste cooking oil (WCO) appears to be a potential carbonaceous source for the synthesis of graphene sand composite (GSC) adsorbent in removing pollutants. This study presents a green synthesis method of GSC using WCO as a sustainable carbon source for the synthesis of GSC through the thermal graphitization method. Characterization analysis conducted on GSC WCO verified the successful coating of WCO onto sand surface and conversion to graphene, which possessed distinct functional groups and features of graphene materials. GSC WCO adsorbent effectiveness in removing Congo Red dye through batch adsorption was studied under the influence of different initial concentrations, and the optimum pH, contact time, and temperature were investigated. The highest pollutant removal was achieved at an initial dye concentration of 20 mg L -1 , 1.0 g of adsorbent dosage, a temperature of 25℃, and 150 min of contact time. The GSC WCO exhibited the maximum capacity of 5.52 mg g -1, was well-fitted to the Freundlich isotherm model, and had an adsorption mechanism that followed the pseudo-second-order kinetic model. The regeneration of GSC WCO adsorbent declined after four cycles, possibly due to the chemisorption of dyes with GSC that resulted in inefficient adsorption. Being a waste-to-wealth product, GSC WCO possessed a great potential to be used for water treatment and simultaneously benefited the environment through the effort to reduce the excessive discharge of WCO.