Abstract
Fabrication of the ZSM-22/Polyethersulfone (ZSM-22/PES) membranes as selective salt
filters represent a growing membrane technological area in separation with the potential of high
economic reward based on its low energy requirements. The incorporation of ZSM-22 zeolite material
as additives into the PES polymer matrix has the prospective advantage of combining both the zeolite
and polymer features while overcoming the limitations associated with both materials. This work
investigated the influence of the nature of the silica precursor on ZSM-22 zeolite hydrothermally
synthesised using colloidal (C60) and fumed (C60) silica to Si/Al of 60. The successful synthesis of
the highly crystalline zeolitic materials was confirmed through XRD, FTIR, and SEM with EDX. The
ZSM-22 additives were directly dispersed into a PES polymeric matrix to form a casting solution for
the preparation of the ZSM-22/PES selective substrate layers via a phase inversion method for salts
rejection. The polymeric PES was selected as an organic network in which the content of the ZSM-22
zeolite (ranging between 0 and 1.0 wt.%), was obtained and characterised by XRD, FTIR, and SEM
analysis, as well as water contact angle (WCA) measurement and dead-end filtration cell. The phase
inversion preparation method has induced the resulting ZSM-22/PES NF substrates anisotropy, as
attributed to a high water flux to the above 700 L·m−2
·h
−1
; high selectivity and rejection of salts to
above 80% is revealed by the obtained results. The materials also exhibited improved antifouling
behavior to above 70% flux recovery ratios. As such, the nature of the silica precursor influences
ZSM-22 zeolite synthesis as a potential additive in the PES polymer matrix and led to the enhanced
performance of the pure PES ultrafiltration membrane.