(578c) Cloud Point Temperature Purification of Butyric Acid from Aqueous Solutions Using Non-Ionic Surfactant

Butyric acid is a volatile organic acid that can be used as starting material for a wide range of applications. Butyric acid can be produced through fermentation and is typically recovered by precipitation, distillation, adsorption, reverse osmosis and membrane filtration. Previous phase equilibrium study demonstrated the ability of a non-ionic surfactant (N23E2) to extract butyric acid from aqueous solutions. After extraction, however, a surfactant-rich phase that contains most of the butyric acid is generated, which requires additional downstream process(es) to produce high purity butyric acid. The present study was conducted to evaluate the cloud point temperature of N23E2 as the main parameter for the aforementioned downstream process(es). For non-ionic surfactants, the cloud point is the temperature when the surfactant tends to separate from a solution to form an almost pure surfactant phase. Typically, cloud point temperatures are measured using a specific solvent, and thus, literature information might not reflect the true cloud point temperature of a given surfactant. Experiments were performed to produce a butyric acid-laden surfactant-rich phase (BLS phase) based on the pre-established phase diagram of butyric acid + N23E2 + water at 35°C. The BLS phase was recovered and incubated at different temperatures from 55 to 70°C for 24 hours. This temperature range was decided based on preliminary observations in the laboratory as well as information provided by the manufacturer of N23E2. After incubation, the resulting phases were sampled and analyzed for butyric acid and surfactant concentrations using liquid chromatography. Initial results indicated phase separation at various temperatures tested. It is hypothesized that the butyric acid will separate out of the surfactant and will constitute majority of the phase generated. Ongoing experiments are designed to determine the purity of the butyric acid produced using the cloud point temperature of the surfactant as the main parameter. The non-toxic and biodegradable characteristics of this non-ionic surfactant as solvent would be useful in developing a purification process for producing butyric acid as a food ingredient or component in cosmetic formulations.