Application of Response Surface Methodology for Lipase Catalyzed Synthesis of 2-Ethylhexyl Palmitate in a Solvent Free System Using Ultrasound

Abstract

This study aims at clean production of 2-ethylhexyl palmitate catalyzed by lipase Fermase CALB 10000 in a solvent-free system using ultrasound technology. The central composite design (CCD) of response surface methodology with 4 factors at 3 levels consisting of acid to alcohol molar ratio (1:3-1:7), enzyme loading (3 %-7% (w/w)), ultrasound power (60-100 W) and duty cycle (30%-70 %) was used for optimization of the reaction. All the reactions were carried out at a fixed temperature of 60°C, 200 rpm and reaction time (120 min). The statistical software, Design-Expert 9.0, was used for regression analysis and graphical analysis of the responses obtained by running the set of designed experiments. The polynomial equation of quadratic order was employed to fit the experimental data. The operating conditions for optimum synthesis of 2-ethylhexyl palmitate were molar ratio of 1:5.5, 5.61 % (w/w) of the enzyme with ultrasound power 79.54 W and duty cycle 48.04 %, leading to a reaction conversion as high as 96.56% in 120 min. The operational stability of the enzyme was maintained at >70% conversion up to 5 cycles. Thus, ultrasound is a promising green technology for the lipase catalyzed synthesis of ethylhexyl esters.