AF2400/PTFE composite membrane for hexane recovery during vegetable oil production

The use of OSN in the production of edible oil conserves energy making it extremely attractive, however, it should be noted that a physically and chemically stable membrane for this is required. Considering this, we selected the AF2400/PTFE composite membrane to recover hexane from the crude mixture of soybean oil and hexane via the OSN process. We carried out pure solvent permeation and rejection experiments, which verified the effectiveness of the membrane in separating and recovering hexane or other aliphatic solvents. We also conducted a comprehensive study on the effect of operational parameters, including long-term operation, transmembrane pressure, oil concentration and operational temperature. Permeate flux value varied in the range of 0.8–1.1 l m⁻² h⁻¹ bar⁻¹ with oil rejection above 98% before or after physical aging for 1440 h in pure hexane. Experimental results confirmed the effectiveness of the AF2400/PTFE composite membrane in hexane recovery, showing high oil rejection and excellent long-term operational stability. We attributed the excellent performance of the AF2400/PTFE composite membrane to its unique surface properties, confirmed by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The study presented herein indicates that fluoropolymer based membranes are promising candidates in aliphatic solvent separation via the OSN process.