Optimization of the Extraction of Free Fatty Acids Applied to Biodiesel Production

Abstract

The liquid-liquid extraction of free fatty acids (FFA) from residual oils and fats for biodiesel production, employing methanol as the solvent, has been optimized using process simulation and response surface methodology. The parameters investigated were temperature, number of stages and solvent-to-feed ratio (S/F). Responses evaluated were FFA mass fraction in the oil-rich phase (wFFA B ) and total cost, using yellow and brown greases as the raw materials. Quadratic and linear models were fitted for wFFA B and cost responses, respectively. The optimal conditions satisfying technical (wFFA B ≤ 0.5%) and economic (minimum cost, including capital and operation costs, except for raw material cost) criteria were 321 K, 6 stages, S/F = 1.27, wFFA B = 0.41%, cost = $84.93/ton (yellow grease), and 318 K, 6 stages, S/F = 1.32, wFFA B = 0.49%, cost = $102.89/ton (brown grease).

Extraction of Free Fatty Acid Mixtures from Rice Bran Oil by Aqueous Renewable Alcohols: Liquid-liquid Equilibrium Diagram and Number of Equilibrium Stages

“…For removing FFAs from vegetable oils, solvent extraction is known to be a potential alternative to the conventional methods, as revealed by Albuquerque, et al in [25]. The solvents that are mentioned to be suitable for this application are short-chain alcohols, among others ethanol and isopropanol.…”