Comparative Study on Optimization of Factors Affecting Epoxidation-Hydroxylation Reaction for The Production of Waste Cooking Oil Based-Polyol

Abstract

Raw materials for the production of polyurethane (PU), including polyols and isocyanate are derived from crude oils which pose a multitude of environmental impacts. While, the exploits of pure cooking oil, like palm oil used as a feedstock for polyol, could cause a bio-crisis, triggered by the imbalance of its demands and supplies. Hence, the utilization of vegetables or cooking oil from waste is mandatory to resolve the impacts. This study revolves around the comparative assessment of waste cooking oil (WCO) over pure cooking oil and the optimization of temperature, different acids, and catalysts, and hydrogen peroxide loading in the production of polyol via epoxidation and hydroxylation reaction. An acid reacts with hydrogen peroxide and produces peroxy-acid and water, which then reacts with WCO, the first step through the epoxidation process. Afterward, to produce polyol the breaking of the epoxidized-ring fatty acids is carried out by the reaction of hydroxylation aided by catalyst i.e., hydrochloric acid, sulphuric acid, or phosphoric acid. Notoriously, WCO has a similar triglyceride structure as pure cooking oil. However, even after filtration, some factors have a considerable effect on its fatty acid compositions such as duration of usage, exposure of temperature, and type of food used during cooking. Regarding temperature when producing polyol, it is discovered that higher temperature led to more ring-opening, nonetheless, prolonged high temperature causes more side reactions which are undesirable. Additionally, acetic acid has a surpassing oxygen carrier property over formic acid in epoxidation reaction. Alongside, sulphuric acid is the most efficient inorganic acid catalyst due to stronger acid exhibits profound ring-opening of epoxidized oil. Furthermore, higher loading of hydrogen peroxide is preferable. Lastly, variations of extraction of sustainable acids which can be used as oxygen carriers for epoxidation i.e., formic acid and acetic acid derived from empty fruit bunch and food wastes are also demonstrated