No abstract

Metal organic frameworks (MOFs) represent one of the largest classes of porous crystalline materials. MOFs have been increasingly applied as functionalizing agents for membranes because of their porosity, high surface area, small particle size, aspect ratio control, tuneability, compatibility with a polymeric network, and exuberance of diverse functional groups. In this comprehensive review paper, we discuss achievements, opportunities, and challenges related to the functionalization of different types of membranes using MOFs for water and wastewater treatment and desalination. The current synthesis and fabrication approaches of MOF-functionalized membranes were identified and critically reviewed. The effects of MOFs on membrane performance, including permeation, selectivity, and antifouling, were discussed. Also, the application of MOF-functionalized membranes in aqueous environments for conventional applications such as heavy metal removal and emerging applications such as resource recovery was enunciated. Finally, recommendations and future directions were provided for further improvement in the field of MOF-functionalized membranes for water treatment and reuse.

The new ZIF named UZAR-S13 is formed by Zn 2+ and 4(5)-(hydroxymethyl)imidazolate. UZAR-S13 has two distinct phases according to SEM and XRD: amorphous spheres and sheet crystals. UZAR-S13 and byproducts, with no N 2 adsorption, rendered a notable CO 2 uptake (up to 3.8 mmol g-1 at 30 bar and 0 °C), approaching values of known ZIFs. The most promising materials were included as fillers in mixed matrix membranes based on copolyimide 6FDA-DAM to study the separation of CO 2 /CH 4 , CO 2 /N 2 , H 2 /CO 2 and H 2 /CH 4. The pore blocking hindered the gas flow of bulky molecules (CH 4 , N 2 and CO 2). The high CO 2 adsorption on sheet crystals also contributed to the decrease in the permeability of CH 4 , N 2 and CO 2 , giving poor selectivities. In contrast, the MMMs improved both the H 2 /CH 4 selectivity (8.9-12.7 vs. 7.2) and permeability of H 2 (544-597 vs. 505 Barrer) of the bare 6FDA-DAM membrane. This emphasizes the potential application of the fillers in the separation by molecular sieving of gas mixtures without CO 2 .

Nanosheets obtained from MOF MIL-53(Al) applied in mixed matrix membranes with improved CO2/N2 and CO2/CH4 selectivities.