Dual‐layer PBI/P84 hollow fibers for pervaporation dehydration of acetone

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Acetone dehydration via pervaporation is challenging, because acetone and water have close molecular sizes, and acetone has a much higher vapor pressure than water. Acetone is also a powerful solvent, which dissolves or swells most polymers. We have developed novel polybenzimidazole/BTDA-TDI/MDI (PBI/P84) dual-layer hollow fibers for pervaporation dehydration of acetone for industrial and biofuel separations. Both thermal and chemical crosslinking modifications were applied to the membranes to investigate their effectiveness to overcome acetone-induced swelling. Thermal treatment can effectively enhance separation performance, but performance stability can only be achieved through the crosslinking modification of PBI. Crosslinking by p-xylene dichloride followed by a thermal treatment above 250 C show significant effectiveness to improve and stabilize pervaporation performance. The fractional free volume of the PBI selective layer reduces from 3.27 to 1.98% and 1.33%, respectively, after thermal treatment and a combination of chemical/thermal crosslinking modifications characterized by positron annihilation spectroscopy.The as-spun PBI/P84 dual-layer hollow fiber membrane shows an acetone/water separation factor of only 2.2 and a Figure 2. Sorption results of PBI and P84 dense films after one-week and one-month immersion in acetone and water.Figure 3. FE-SEM images of the cross-section morphology of the original PBI/P84 dual-layer hollow fiber. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] Figure 7. FE-SEM images of the cross-section morphology of the outer layer outer edge of original and thermaltreated PBI/P84 dual-layer hollow fibers at various temperatures.

Pervaporative recovery of acetone from water using mixed matrix blend membranes

“…The annual consumption of acetone is around 6 million ton [13]. Although there are a good many number of reports on the dehydration of acetone [13][14][15][16][17] but there are few reports on the recovery of acetone using a suitable pervaporation membrane [18,19]. Acetone is miscible in all proportion with water.…”

Layer-by-layer (LbL) polyelectrolyte membrane with Nexar™ polymer as a polyanion for pervaporation dehydration of ethanol

“…Fig.10 shows the change of R-parameter as a function of incident energy. The larger R-parameter near the surface is probably attributed to the back diffusion of positronium [34,43,44]. As the positron energy increases to ~1.2 keV, the R-parameter drops quickly to the minimum and remains in a valley plateau until ~3 ϭϳ keV, which indicates the Nexar TM polymer/PEI LbL selective layer.…”

Review: membrane materials for the removal of water from industrial solvents by pervaporation and vapor permeation

“…(c). In some cases, the polyimide is used in the preparation of the porous support layer for a dense selective layer of another polymer . Thermally rearranged (TR) polymers have recently been reported for solvent dehydration .…”

“…In some cases, the polyimide is used in the preparation of the porous support layer for a dense selective layer of another polymer. 130,131 Thermally rearranged (TR) polymers have recently been reported for solvent dehydration. 132,133 TR polymers are formed when ortho-functional polyimides are thermally treated at temperatures up to about 450 ∘ C, causing a condensation reaction to yield a heterocyclic, aromatic structure that is both thermally stable and resistant to swelling.…”