PHYSICOCHEMICAL CHARACTERIZATION OF USED COOKING OIL: ENVIRONMENTAL IMPLICATIONS AND REUSE POTENTIAL

Abstract

Improper disposal of waste cooking oil (WCO) poses significant environmental challenges, necessitating effective reuse strategies aligned with circular economy principles. This study aimed to perform the physicochemical characterization of WCO from residential and commercial sources to propose specific management routes based on degradation levels. Analytical determinations included density, acid value, peroxide value, and iodine value, performed in triplicate. The results revealed high heterogeneity and severe degradation, with acidity ranging from 1.15 to 5.82 mg KOH/g and peroxide values reaching 111.92 meq O₂/kg. Notably, density increased compared to virgin oil (0.95 g/mL), reaching up to 1.17 g/mL. Pearson correlation analysis indicated a significant positive association between hydrolytic and oxidative degradation (r = 0.8349; p = 0.0014). Cluster Analysis using the Gap Statistic method successfully categorized samples into four groups. Based on this, specific valorization routes were proposed: Cluster A (lower degradation) for biotechnological applications (enzymatic hydrolysis); Cluster D (intermediate) for chemical production of esters; and Cluster B (restaurant/high degradation) for energy purposes (biodiesel). These findings demonstrate that physicochemical profiling is a viable tool for directing WCO into appropriate value chains, transforming an environmental pollutant into a sustainable resource.