Dehydration Of Tetrahydrofuran Research Articles

Dehydration of tetrahydrofuran (THF) by pervaporation using crosslinked copolymer membranes

Tetrahydrofuran (THF) is an important volatile intermediate used in chemical industries and its separation from water is encountered in many application. Three different copolymers of acrylamide with increasing amount of 2-hydroxyethyl methacrylate (HEMA), i.e. PAMHEMA-1, -2 and -3 were synthesized and the crosslinked (gelled) copolymer membranes made from these sol copolymers were used for pervaporative dehydration of THF over the concentration range of 0–14 wt% water in feed. These extremely hydrophilic gel copolymer membranes were found to be highly water selective in both sorption and diffusion through the membranes. Water flux was found to decrease with increase in degree of crosslinking from PAMHEMA-1 to 3 copolymer membranes. Among the three membranes PAMHEMA-1 membrane showed very high water selectivity (216) and reasonable flux (570 gm/m 2 h for 0.56 wt% of water in feed at 50 °C temperature). Water was also found to have a strong positive coupling effect on THF permeation. The membranes were found to show both sorption as well as diffusion selectivity for water.

Sodium alginate-TiO2 mixed matrix membranes for pervaporation dehydration of tetrahydrofuran and isopropanol

Mixed matrix polymer membranes containing nanosized (21 nm) TiO2 particles dispersed in sodium alginate (NaAlg) have been prepared by solution casting and cross-linking with glutaraldehyde. These membranes were tested for pervaporation (PV) dehydration of tetrahydrofuran (THF) and isopropanol from their aqueous solutions at 30°C. Results have been compared with plain cross-linked NaAlg membrane. Plain cross-linked NaAlg membrane could remove up to a maximum of 97 wt% of water at higher feed water concentrations of the feed with considerably much lower selectivity. Infinite selectivity values with reasonable fluxes were observed for the mixed matrix membranes of NaAlg in the investigated feed compositions of 5–15 wt% water containing THF and 10–20 wt% of water containing isopropanol feed mixtures. Fluxes of NaAlg-TiO2 mixed matrix membranes are slightly lower than those of plain the NaAlg membrane for the investigated range of feed water compositions.

Dehydration of tetrahydrofuran by pervaporation using a composite membrane

Tetrahydrofuran (THF) is a strong aprotic solvent, commonly used in the pharmaceuticals industry due to its broad solvency for both polar and non-polar compounds. THF and water form a homogeneous azeotrope at 5.3 wt.% water thus simple distillation is not feasible to dehydrate THF below this concentration. Pervaporation offers a solution since it is not governed by vapour–liquid equilibria. However many polymer-based pervaporation membranes are cast utilizing THF as the casting solvent and so these membranes have a tendency to swell excessively in its presence. This results in poor separation performance and poor long-term stability and thus renders these membranes unsuitable for THF dehydration. In this study, a new membrane available from CM Celfa, CMC-VP-31 has been tested for the dehydration of THF. The membrane shows excellent performance when dehydrating THF with a flux of over 4 kg m −2 h −1 when dehydrating THF containing 10 wt.% water at 55 °C dropping to 0.12 kg m −2 h −1 at a water content of 0.3 wt.%. The permeances of water and THF in the membrane were calculated to be 11.76 × 10 −6 and 7.36 × 10 −8 mol m −2 s −1 Pa −1, respectively, at 25 °C and found to decrease in the membrane with increasing temperature to values of 6.71 × 10 −6 and 1.63 × 10 −8 mol m −2 s −1 Pa −1 at 55 °C. The flux and separation factor were both found to increase with an increase in temperature thus favouring the operation of CMC-VP-31 at high temperatures to optimize separation performance.

Poly(vinyl alcohol)/poly(vinyl pyrrolidone) interpenetrating polymer network: Synthesis and pervaporation properties

AbstractNovel interpenetrating polymer network membranes were made from poly(vinyl alcohol)/poly(vinyl pyrrolidone) blends of different compositions. The two polymer components were independently crosslinked chemically with glutaraldehyde and photochemically with 4,4′‐diazostilbene‐2,2′‐disulfonic acid disodium salt. The membrane performances were studied in pervaporation of tetrahydrofuran (THF)/water and THF/methanol mixtures. It was found that the membranes were excellent in THF dehydration, but much less efficient for the separation of THF/methanol mixtures. The pervaporation results were consistent with the membrane swelling data. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2808–2814, 2003