Surfactant Production of Methyl Ester Sulfonate from Virgin Coconut Oil using Aluminum Oxide with Microwave Assistance

Abstract

As a surfactant, methyl ester sulfonate (MES) can be produced from virgin coconut oil (VCO) raw materials through the following stages: transesterification, sulfonation, and purification. The transesterification process was carried out to produce methyl esters by reacting VCO with methanol in a mole ratio of 1:41 using a 1% KOH catalyst at a microwave power of 300 W for 60 min. The effects of microwave power and mole ratios between methyl esters and sodium bisulfite in the sulfonation process were investigated. The sulfonation process was carried out using a 1% aluminum oxide catalyst. The purification process was carried out by reacting MES with 35% v/v methanol at 150 W of microwave power for 10 min. The resulting MES was analyzed using gas chromatography and Fourier transform-infrared (FT-IR) spectroscopy. The optimum conditions for surfactant production included a microwave power of 450 W and reactant mole ratio of 1:1, which resulted in a surface tension of 37.9 dyne/cm, pH of 4.21, density of 0.87 g/mL, and viscosity of 3.33 cSt. Based on the FT-IR analysis, the vibrational strain of the sulfonate group was detected at a peak value of 1014.42 for symmetrical S-O and 722.24 cm-1 for asymmetrical S-O.