Ethanol recovery from dilute aqueous solution by perstraction using supported ionic liquid membrane (SILM). (20th May 2021)

• Record Type: Journal Article
• Authors: Huang, Ting-Yi; Ho, Jia Shin; Goh, Shuwen; Chong, Tzyy Haur
• Is Part Of: Journal of cleaner production. Volume 298(2021)
• Publication Date: 2021-05-20
• Subjects: Perstraction -- Supported ionic liquid membrane (SILM) -- trihexyl(tetradecyl)phosphonium ionic liquids -- Ethanol extraction -- Fermentation products; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2021.126811
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: The recovery of ethanol from dilute aqueous solution by supported ionic liquid membrane (SILM) perstraction was investigated using three potential extracting solvent of trihexyl(tetradecyl)phosphonium ionic liquids (THTDP IL): [THTDP][Br], [THTDP][N(CN)2 ] and [THTDP][Tf2 N], and three potential polymeric microporous membranes: polyvinylidene fluoride (PVDF) (hydrophilic Durapore® GVWP and hydrophobic Durapore® GVHP) and polypropylene (PP). The solvent was chosen based on hydrophobicity, thermal stability and negligible vapor pressure; while the membrane was chosen based on physicochemical properties, commercial availability and affordability. The optimized combination of solvent and membrane was assessed in a perstraction system. The [THTDP][N(CN)2 ]-GVHP SILM gave the best overall performance in terms of extraction and stability. At a feed concentration of 2 wt% ethanol, the selected SILM was able to maintain its functionality for ∼240 h without observable phase intermixing. Despite being subjected to constant lateral shear on the aqueous side, the SILM retained its integrity by maintaining a high ethanol flux of > 2.2 kg/m 2 ·h (vs. ∼10 -4 – 10 -1 kg/m 2 ·h in pervaporation) and selectivity of > 320 (vs. ∼20 in liquid-liquid extraction). Subsequently, the extracted ethanol was recovered from IL by single-stage vacuum-distillation with a final purity of 80% (vs. ∼20% in single-stage vacuum-distillation alone) and an overall selectivity of 200. The long-term stability, high flux and superior selectivity of the SILM perstraction system makes it a promising alternative to other energy intensive purification techniques such as distillation for the extraction of dilute ethanol as low as 2 wt% from fermentation broths. Graphical abstract: Image 1 Highlights: Recovery of ethanol from 2 wt% dilute aqueous solution by SILM perstraction. [THTDP][N(CN)2 ]-GVHP SILM shows long term stability without phase intermixing. Phase intermixing due to SILM instability mechanism and interface re-establishment. SILM retains high ethanol flux > 2.2 kg/m 2 ·h and selectivity > 320. Perstraction-vacuum distillation gives high ethanol purity (80%) and selectivity (200).