Vacuum membrane distillation is foreseen as a membrane unit operation capable of providing access to drinking water in the future, through the saline water desalination. To increase the permeation of standard hydrophobic membranes, such as PVDF, mixed matrix membranes are defined as the next generation of membranes and prepared by adding a filler into the polymer phase. Therefore, the aim of this work was to evaluate the effect of a chabazite zeolite filler (from 0.5 to 4 wt%) into PVDF membranes, which were prepared by a non-solvent induced phase separation, and later tested, for the first time, for water desalination application at different operating temperatures. Chabazite was selected due to its high-water affinity (comparable to zeolite 4 A or 13X) and exceptional hydrothermal stability. To explain the impact of the chabazite, resulting membranes were thoroughly characterized with different analytical techniques, such as scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), nitrogen sorption, gas liquid porometry, water contact angle, and mechanical testing. As part of the outcomes, significant enhancement of the desalination performance was observed upon the addition of the chabazite; with the 4 wt% formulation being the best-performing. The permeate flux at 40 °C increased 2.7 times compared to the pristine PVDF membrane, e.g., 6.133 ± 0.540 and 2.256 ± 0.203 kg m− 2 h− 1, respectively. Despite different nature of the chabazite (hydrophilic) and PVDF (hydrophobic), the compatibility was sufficient to avoid formation of non-selective gaps and completely reject salt (99.99%). The membrane performed stable, with high salt rejection, for over 16 h before pore wetting was observed. Although, some issues with chabazite aggregation and pore wetting were observed, the chabazite demonstrated promising potential as a filler that enhances water transport.
Plata-Gryl et al. (Tue,) studied this question.