High Yield Dihydroxystearic Acid (DHSA) Based on Kinetic Model from Epoxidized Palm Oil

Abstract

In recent years, studies related to the epoxidation of fatty acids have garnered much interest due to the rising demand for eco-friendly epoxides derived from vegetable oils. From the epoxidation reaction, there is a side reaction involving epoxide and water. This reaction produces a by-product – dihydroxystearic acid (C<sub>18</sub>H<sub>36</sub>O<sub>4</sub>, DHSA). DHSA is one of the chemical precursors in the production of cosmetic products. Therefore, a kinetic model was developed to determine the optimised epoxidation process and concentration of DHSA, where each of the reactions was identified. The kinetic rate, <i>k</i> parameters obtained were: <i>k</i><sub>11</sub> = 6.6442, <i>k</i><sub>12</sub> = 11.0185, <i>k</i><sub>21</sub> = 0.1026 for epoxidation palm oleic acid, and <i>k</i><sub>41</sub> = 0.0021, <i>k</i><sub>51</sub> = 0.0142 in degradation process. The minimum error of the simulation was 0.0937. In addition, DHSA yield optimisation was done through Taguchi method, and the optimum conditions obtained were H<sub>2</sub>O<sub>2</sub>/oleic acid – OA unsaturation molar ratio 1 : 1 (level 2), formic acid – FA/OA unsaturation molar ratio 0.5 : 1 (level 1), temperature 35 °C (level 1), and agitation speed 100 rpm (level 1). A high yield of DHSA can be achieved under these conditions.