Preparation and Characterization of Polyvinylalcohol/Polysulfone Composite Membranes for Enhanced CO(2)/N(2) Separation

The unique properties of polyvinyl alcohol (PVA) and polysulfone (PSf), such as good membrane-forming ability and adjustable structure, provide a great opportunity for CO(2)-separation membrane development. This work focuses on the fabrication of PVA/PSf composite membranes for CO(2)/N(2) separations. The membranes prepared by coating a 7.5 wt% PVA on top of PSf substrate showed a relatively thin selective layer of 1.7 µm with an enhanced CO(2)/N(2) selectivity of 78, which is a ca. 200% increase compared to the pure PSf membranes. The CO(2)/N(2) selectivity decreases at a rapid rate with the increase of feed pressure from 1.8 to 5 bar, while the CO(2) permeance shows a slight reduction, which is caused by the weakening of coupling transportation between water and CO(2) molecules, as well as membrane compaction at higher pressures. Increasing operating temperature from 22 °C to 50 °C leads to a slight decrease in CO(2) permeance, but a significant reduction in the CO(2)/N(2) selectivity from 78 to 27.1. Moreover, the mass transfer coefficient of gas molecules is expected to increase at a higher velocity, which leads to the increase of CO(2) permeance at higher feed flow rates. It was concluded that the CO(2) separation performance of the prepared membranes was significantly dependent on the membrane operating parameters, and process design and optimization are crucial to bringing CO(2)-separation membranes for industrial applications in post-combustion carbon capture.