AEL Zeolite Nanosheet-Polyamide Nanocomposite Membranes on alpha-Alumina Hollow Fibers with Enhanced Pervaporation Properties

Polyamide (PA)-based nanofiltration membranes fabricated via interfacial polymerization (IP) are widely studied for water desalination. The formation of hybrid (nanocomposite) membranes comprising PA along with nanoporous materials has the potential to increase water flux while maintaining salt rejections with low energy input. We report a new type of nanocomposite membrane comprising high-aspect-ratio AEL molecular sieve nanosheet coating and PA, fabricated on alpha-alumina hollow fibers. We find that the AEL nanosheet coating acts as a semipermeable reservoir to store diamine molecules and thus control the interfacial polymerization to form thin, continuous AEL/PA nanocomposite membranes on the ceramic fiber surfaces. The nanocomposite AEL/PA membranes are similar to 400 nm thick and exhibit high water permeance and NaCl rejection in pervaporative desalination at low (2 g/L NaCl) and high (36 g/L NaCl) salt concentrations representative of brackish water and seawater, respectively. The membranes are stable over the longer-term operation for 150 h in pervaporative desalination. This work suggests a new strategy for developing high flux PA-based thin-film nanocomposite membranes for water treatment by utilizing high-aspect-ratio microporous zeolite nanosheets. The preparation of these membranes on ceramic hollow fibers is also useful for their scalable fabrication.