Simultaneous improvement in solvent permeability and deacidification of soybean oil by nanofiltration

Abstract

In this paper, soybean oil deacidification and hexane removal using laboratory scale solvent resistance nanofiltration membranes based technique is presented. Composite nanofiltration membranes made of different polymers poly(vinylideneflouride) (PVDF), polydimethylsiloxane (SI), polycarbonate (PC), and glycerol were tested to remove the hexane and free fatty acid (FFA) from soybean oil/hexane miscella (oil feed solution 10, 25, and 35% w/w) at 20 bar of transmembrane pressure and 30°C, in a dead-end filtration set up. All membranes tested showed low fouling phenomena and high stability in the presence of hexane throughout the membrane pre-treatment and permeation procedure. The PVDF-10SI-1PC membrane showed the best performance achieving a miscella permeability of L m = 6.8 9 10 -6 L (h m bar) -1 , oil and FFA sieving efficiency of b (oil) = 0.21(80% of oil rejection) and b FFA = 2.43 (27% of FFA removal), respectively, at oil feed concentration of 25%. Apart from these specific properties, the PVDF-10SI-1PC membrane presented excellent mechanical and chemical resistances and low reversible fouling. The results demonstrate that membrane technology can attain a high efficiency in the simultaneous solvent recovery and deacidification of oil/ hexane miscella commonly processed in the soybean oil industry.

Performance and fouling analysis of an ultrafiltration membrane for lecithin separation from isopropanol-oleic acid-lecithin mixtures

“…In contrast, the rejection of FFA shows a low value, with the highest rejection only 16.39%. FFA has a molecular weight of 300 Da, which is smaller than the membrane pore [18,24]. The low value of FFA rejection also confirms a low selectivity of the membrane.…”

Membrane technology for vegetable oil processing—Current status and future prospects

“…On the contrary, there was no appreciable selectivity for tocopherols and tocotrienols while processing undiluted and hexane‐diluted palm oil (Arora et al., 2006). Similarly, studies with acetone‐palm oil‐palmitic acid model miscella showed that the NF membranes (300‐500 Da) rejected palmitic acid in the range of 56‐86% (Ismail & Ghazali, 2018), contradicting preferential FFA permeation reported in several other real and model hexane‐oil systems (Firman et al., 2013, 2017; Raman et al., 1996). These results suggest that the typical composition of crude vegetable oils, as well as the solvent, could play a role in the relative permeation of these minor compounds.…”

“…In another study (Firman et al., 2013), a lab‐cast PDMS membrane displayed an oil rejection of 80% and FFA reduction of 40% (selectivity ∼1.85), maintaining a higher miscella flux of 20.3 L/m 2 /h, while processing a degummed soybean oil miscella (25% oil with 0.5% FFA). To facilitate FFA permeation, polycarbonate was incorporated to the PDMS active layer (Firman et al., 2017) and the induced hydrophilicity improved the deacidifying performance (selectivity ∼2.43) without practically affecting the desolventizing efficiency (Ro 79%; 19.3 L/m 2 /h).…”

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

“…It has to be done in a very tightly closed system since the extract is as volatile as the solvent. Alternatives for removing FFA from vegetable oils that are still under development include catalytic esterification as reported by Habaki,et al in [18], enzymatic esterification as reported by Wang,et al in [19], enzymatic amidation as reported by Wang,et al in [20], membrane separation as reported by Azmi, et al in [21] and Firman, et al in [22], deep eutectic ionic liquid extraction as reported by Zullaikah,et al in [23] and Zahrina,et al in [24], and liquid-liquid extraction using volatile organic solvents, which is known as solvent extraction.…”