Reuse of Waste Cooking Oil (WCO) in the Production of Ecological Soap: An Experimental Study of the Saponification Process

Abstract

Improper disposal of waste cooking oil (WCO) represents a significant environmental issue, contributing to sewer system blockages, water contamination, and degradation of aquatic ecosystems. This study aimed to conduct an experimental investigation of the saponification process using waste cooking oil, integrating principles of Organic Chemistry and environmental education. The methodology involved the reaction between triglycerides present in the residual oil and sodium hydroxide (NaOH) under controlled stirring and heating conditions, resulting in the formation of fatty acid salts (soap) and glycerol. The results confirmed the occurrence of alkaline hydrolysis of esters, evidenced by the formation of a pasty mass followed by solidification. Structural analysis demonstrated that the produced soap exhibits amphiphilic characteristics, with a nonpolar hydrocarbon chain derived from fatty acids and a polar carboxylate end, enabling micelle formation in aqueous medium and explaining its detergent action. Beyond validating chemical concepts, the experiment demonstrated the technical feasibility of reusing waste cooking oil as a sustainable alternative aligned with Green Chemistry principles. The activity also relates to the Sustainable Development Goals, particularly SDG 12 (Responsible Consumption and Production) and SDG 6 (Clean Water and Sanitation), by contributing to water pollution reduction and promoting circular economy practices. The production of ecological soap is therefore an effective strategy from scientific, educational, and environmental perspectives.