Forward Osmosis Membranes Fabricated on Microfilter Support with Sacrificial Zeolitic Imidazolate Framework...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Global water scarcity necessitates advanced water desalination technologies.
• Forward osmosis (FO) offers low energy demand but faces challenges with membrane performance, particularly internal concentration polarization and active layer defects.
• Polyamide (PA) thin-film composite membranes are crucial for FO, but their performance depends heavily on support layer characteristics.

Purpose of the Study:

• To engineer high-performance FO membranes by addressing limitations in PA active layers and support interactions.
• To investigate the use of a sacrificial zeolitic imidazolate framework (ZIF-67) interlayer to improve PA membrane morphology and FO performance.
• To optimize the ZIF-67 interlayer by tuning precursor concentrations for enhanced water flux and reduced reverse salt flux.

Main Methods:

• Fabrication of PA thin-film composite membranes on microfiltration supports.
• Modification of support membranes with a sacrificial ZIF-67 interlayer prior to interfacial polymerization.
• Tuning cobalt and imidazole concentrations to control ZIF-67 interlayer density and properties.
• Characterization of membrane morphology and evaluation of FO performance (water flux and reverse salt flux).

Main Results:

• The ZIF-67 interlayer effectively reduced support pore size and provided a uniform surface for controlled PA formation.
• Optimized membranes achieved a water flux of 25.5 LMH and a reverse salt flux of 4.27 gMH.
• Increasing the support pore size to 450 nm with the ZIF-67 interlayer further boosted water flux to 40.1 LMH.
• The ZIF-67 interlayer was successfully removed by water post-PA formation, demonstrating its sacrificial nature.

Conclusions:

• A removable ZIF-67 interlayer is an effective strategy for fabricating high-performance FO membranes.
• This method overcomes limitations associated with traditional support layers, leading to improved water flux.
• The developed membranes show significant potential for efficient water desalination applications.