Abstract
Butyric acid is a short-chain volatile fatty acid (VFA) that has emerged as a versatile platform molecule with a wide range of industrial applications. Traditionally, VFAs are synthesized from fossil-based raw materials; however, they can also be produced through fermentation of renewable biomass sources. However, recovering these acids produced by biomass fermentation remains one of the most critical and cost-intensive steps, as the complex nature of fermentation broths complicates separation and can account for nearly half of total production costs. Among available recovery strategies, liquid-liquid extraction stands out as a desirable option due to its high selectivity and efficiency for VFA separation. Various types of solvents have been proposed in the literature; however, in recent years, green solvents have emerged as environmentally friendly alternatives. ?-Valerolactone (GVL) is a chemically stable cyclic solvent (C5H8O2) primarily produced from levulinic acid or furfural, which are renewable chemicals. Owing to its favorable physicochemical properties, GVL can serve as a sustainable and green alternative to conventional organic solvents. This study evaluated the efficiency of GVL for the liquid-liquid extraction of butyric acid from fermentation broth. Experimental conditions were optimized by varying the pH (2.5–4.5), stirring time (1–3 hours), solvent-to-butyric acid ratio, and butyric acid concentration. The results indicate that the highest separation efficiency for butyric acid was achieved at a pH of 2.5 and a stirring time of at least 2 hours. Separation efficiencies of over 78% were obtained for butyric acid in the best condition tested, which implies that GVL may be a promising solvent for butyric acid separation from fermentation broth.
