The systematic evaluation of the gas transport properties related to dierences in the historyof the samples is a useful tool to appropriately design a membrane-based gas separation system.The permeation rate of six pure gases was measured over time in asymmetric hollow-fiber (HF)samples, that were prepared according to the non-solvent-induced phase separation in dierentoperation conditions, in order to identify their response to physical aging. Four types of HFshaving a dierent structure were analyzed, comparing samples spun in a triple-orifice spinneretto HFs prepared using a conventional spinneret. A generalized gas permeance decline, coupled toa maintained permselectivity for the dierent gas pairs, was observed for all HFs. Instead, H2/N2permselectivity values were enhanced upon aging. Cross-linked hollow-fiber samples showed amarked size-sieving behavior that favored the separation of small species, e.g., hydrogen, fromother larger species and a good stability over time. Some HFs, post-treated using dierent alcohols,presented a permeance decay independently on the alcohol type and a greater selectivity over time.
Effect of Physical aging on gas transport in asymmetric polyimide hollow fibers prepared by triple orifice spinneret
G Clarizia;F Tasselli;P Bernardo
2020
Abstract
The systematic evaluation of the gas transport properties related to dierences in the historyof the samples is a useful tool to appropriately design a membrane-based gas separation system.The permeation rate of six pure gases was measured over time in asymmetric hollow-fiber (HF)samples, that were prepared according to the non-solvent-induced phase separation in dierentoperation conditions, in order to identify their response to physical aging. Four types of HFshaving a dierent structure were analyzed, comparing samples spun in a triple-orifice spinneretto HFs prepared using a conventional spinneret. A generalized gas permeance decline, coupled toa maintained permselectivity for the dierent gas pairs, was observed for all HFs. Instead, H2/N2permselectivity values were enhanced upon aging. Cross-linked hollow-fiber samples showed amarked size-sieving behavior that favored the separation of small species, e.g., hydrogen, fromother larger species and a good stability over time. Some HFs, post-treated using dierent alcohols,presented a permeance decay independently on the alcohol type and a greater selectivity over time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
