Isolation of free fatty acids from brown grease lipids using wiped film evaporation

A wiped-film evaporation (WFE) distillation study conducted from 120°C to 200°C determined that the isolation of free fatty acids (FFA) from pre-treated brown grease lipids (BGL) produced a product with a consistent fatty acid profile, sulfur (S) concentration between 20 and 60 ppm, total acid number (TAN) ranging from 207.4 to 219, and a heavy metal concentration of 4.2 ppm at 180°C. The S/A method produced a quantitative yield of FFA (TAN = 230.3), but the heavy metal and S concentrations increased to 200.8 and 206.7 ppm. HPLC analysis revealed that both procedures could generate an FFA with high purity. The percent weight of the WFE fractions and a combination of HPLC and TAN values determined approximately 90.2% FFA recovery from BGL from the distillation procedure. Subjecting the S/A product to WFE reduced the concentration of the heavy metals to 11.8 ppm, S concentration to 24.3 ppm, and yield to 93.7%. The WFE procedure reduces the need for S/A chemicals, solvents, extractions, drying agents, and rotary evaporation, possibly providing a more efficient pathway to pure FFA. The optimization and adoption of this work will benefit biofuel producers, brown grease processors, waste management companies, and the cosmetics industry.