Pervaporation Membranes That Are Highly Selective for Acetic Acid over Water

Abstract

Supported liquid membrane pervaporation (SLMPV) is a pervaporation process for separating volatile organic compounds (VOCs) from their dilute aqueous solution. It simultaneously integrates extraction of the VOCs from the aqueous solution with flash distillation of the VOCs from the organic phase. By using a liquid membrane consisting of reactive extractants, pervaporation of primarily acetic acid from its aqueous solutions was studied. Limited studies of butyric acid were also done. Among various extractants tested, trioctylamine (TOA) and tridodecylamine demonstrated better performances. The SLM is permselective for acetic acid and butyric acid. The acetic acid selectivity can be as high as 33 for a feed of 1 M at 60°C, an order of magnitude higher than that obtained by any solid polymeric membrane reported in the literature. The simple SLM system demonstrated long-term stability; for example, decreases of about 30% in both pervaporation flux and selectivity were observed over an operational period of 500 h. A new technique of continuous on-line regeneration of the LM during operation maintains completely stable operational performance.

Pervaporation membranes highly selective for solvents present in fermentation broths

“…The experimental procedure followed was similar to that by Qin et al [13]. Feed solution containing different solvents (acetone, ethanol, butanol, and acetic acid) was introduced at a constant flow rate into the shell side of the module from a reservoir by a Masterflex peristaltic pump.…”

“…These include: polymeric membranes made of polydimethylsiloxane (PDMS) (and its composites) [2][3][4][5], polytetrafluoroethylene (PTFE) [2,3,6,7], polyvinyl alcohol (PVA) (and its composites) [8], ceramic membranes [1,[9][10][11][12], such as silicalite (zeolite) membranes, alumina or composite membranes, and liquid membranes [13][14][15][16], of oleyl alcohol, decyl alcohol, tricresylphosphate, tri-n-butylphosphate, etc. In general, the concentrations of solvents in the permeate stream from polymeric membranes and ceramic membranes are lower compared with those from liquid membranes.…”

“…Qin et al [13] studied TOA as a liquid membrane with porous polypropylene hollow fibers for pervaporation with acetic acid. A selectivity of 8-12 was obtained for acetic acid with respect to water at lower temperatures such as 25 • C. The membrane displayed reasonable stability.…”

“…However, in the process of Qin et al [13], the fermentation broth will get contaminated with the liquid membrane which will require constant regeneration. This study proposes to employ a novel coated porous polypropylene-based hollow fiber membrane.…”

Membrane gas transfer of methane and carbon dioxide in submerged coal deposits

“…Wastewater treatment utilizes membranes for bubbleless aeration of activated sludge basins and oxygenation of other surface waters [7,11,12]. Additionally, volatile organic chemicals (VOCs) are removed from air, ionic liquids and other fluids [13][14][15][16][17]. Membranes are also utilized in environmental remediation.…”