Preparation Of Fatty Acid Ethyl Esters From Vegetable Oil Soapstocks

In this paper, the production process of fatty acid esters by utilizing soapstocks had been studied. Firstly, soapstocks were transfered into clean and clear oil by a pre-treatment process including acidification and decoloration. Then further research was did to optimize the enzymatic reaction conditions of soapstock oil and diethyl carbonate. As a product of pre-treatment process, the yield of soapstock oil was 44.31% under the optimal conditions. Then fatty acid ethyl esters were obtained as products by enzymatic reaction of soapstock oil and diethyl carbonate and the yield could reach 98.4% in solvent-free system with DEC/DO molar ratio 3:1 and 5% Novozym 435 (based on the DO weight) at 50℃for 24 h. Most importantly, the yield was still as high as 97.35% when Novozym 435 was reused for ten batches without any treatment. The study also showed that fatty acid ethyl esters produced had good performance and were considered to be utilized as eco-friendly solvent and lubricant. In our research, we also studied the post-process by utilizing diethanolamine to neutralize the residual fatty acid in fatty acid ethyl esters, which could generate alkyl amide as by-product. It also had good lubricity and detergency performance and could be used as oil displacement agent or industrial detergents.The two-step process mentioned above had stable sources of inexpensive feedstocks, and was simple and easy to operate. Diethyl carbonate and Novozym 435 had shown good applicability to soapstock oil, which could avoid the toxicity of lipases from traditional acyl receptors and their by-products. The economical efficiency of enzymatic reaction process was increased by improving the stability of immobilized enzymes and reducing feedstock cost. Therefore, the process had great potential for industrial applications.