Tunability of metal–organic frameworks (MOFs) properties enables them to be tailored for specific applications. In this study, zeolitic imidazole framework 8 (ZIF-8), sub-class of MOF, underwent pre-synthesis and post-synthesis modifications. The pre-synthesis modification using GO (ZIF-8/GO) shows slight decrease in textural properties, while the post-synthesis modification using amine solution (ZIF-8/NH₂) resulted in superior BET surface area and pore volume. Mixed matrix membranes (MMMs) derived from polysulfone (PSf) and the modified ZIF-8s were then prepared via dry/wet phase inversion. The polymer chain flexibility of the resulted MMMs shows rigidification, where ZIF-8/NH₂ as filler resulting higher rigidification compared to ZIF-8/GO. The MMMs were further subjected to pure CO₂ and CH₄ gas permeation experiments. The PSf/ZIF-8/NH₂ shows superior CO₂/CH₄ selectivity (88% increased) while sacrificing CO₂ permeance due to combination of severe polymer chain rigidification and the presence of CO₂-philic group, amine. Whereas, the PSf/ZIF-8/GO possess 64% increase in CO₂ permeance without notable changes in CO₂/CH₄ selectivity.

Dual-layer hollow fiber (DLHF) nanocomposite membrane prepared by co-extrusion technique allows a uniform distribution of nanoparticles within the membrane outer layer to enhance the membrane performance. The effects of spinning parameters especially the air gap on the physico-chemical properties of ZrO₂-TiO₂ nanoparticles incorporated PVDF DLHF membranes for oily wastewater treatment have been investigated in this study. The zeta potential of the nanoparticles was measured to be around –16.5 mV. FESEM–EDX verified the uniform distribution of Ti, Zr, and O elements throughout the nanoparticle sample and the TEM images showed an average nanoparticles grain size of ~12 nm. Meanwhile, the size distribution intensity was around 716 nm. A lower air gap was found to suppress the macrovoid growth which resulted in the formation of thin outer layer incorporated with nanoparticles. The improvement in the separation performance of PVDF DLHF membranes embedded with ZrO₂-TiO₂ nanoparticles by about 5.7% in comparison to the neat membrane disclosed that the incorporation of ZrO₂-TiO₂ nanoparticles make them potentially useful for oily wastewater treatment.

Adsorptive ultrafiltration membrane is an emerging field that holds great promise for achieving high efficiency removal of various pollutants such as metal ions and organic pollutants. As a result, significant research efforts have been directed towards the utilization of GO due to its unique properties including good hydrophilicity, large surface area, excellent chemical and mechanical stability which can impart better membrane properties and performance. Recent advances in this field revealed that the utilization of graphene oxide (GO) is highly beneficial in improving key membrane properties including surface charge, hydrophilicity, water permeability as well as the adsorption performance. Therefore, this short review provides valuable insight into the performance of GO/GO modified-based membranes, GO/polymeric-based membrane and GO-modified/polymeric-based membrane for various pollutants. The application of GO in ultrafiltration (UF) membranes is anticipated to provide an attractive and viable route towards achieving high performance adsorptive UF membranes for water and wastewater treatment.