Conversion of Free Fatty Acid in Calophyllum inophyllum Oil to Fatty Acid Ester as Precursor of Bio-Based Epoxy Plasticizer via SnCl2–Catalyzed Esterification

The preparation and application of bio based plasticizers derived from vegetable oils has gained increasing attention in the polymer industry to date due to the emerging risk shown by the traditional petroleum-based phthalate plasticizer. Epoxy fatty acid ester is among the prospective alternative plasticizers since it is ecofriendly, non-toxic, biodegradable, low migration, and low carbon footprint. Epoxy plasticizer can be synthesized by the epoxidation reaction of fatty acid ester. In this study, the preparation of fatty acid ester as a green precursor of epoxy ester plasticizer was performed via esterification of free fatty acid (FFA) in high acidic Calophyllum inophyllum Seed Oil (CSO) using methanol in the presence of SnCl2.2H2O catalyst. The analysis of the process variables and responses using Box–Behnken Design (BBD) of Response Surface Methodology (RSM) was also accomplished. It was found that the quadratic model is the most appropriate model for the optimization process. The BBD analysis demonstrated that the optimum FFA conversion and residual FFA content were 75.03% and 4.59%, respectively, achieved at the following process condition: a reaction temperature of 59.36 °C, a reaction time of 117.80 min, and a catalyst concentration of 5.61%. The fatty acid ester generated was an intermediate product which can undergo a further epoxidation process to produce epoxy plasticizer in polymeric material production.