Implementation and utilization of Zeolitic imidazolate frameworks (ZIFs) based membranes in wastewater treatment: A review

For the last two decades there has been momentous development in the Metal Organic Frameworks (MOFs) field. There are two major building blocks of MOFs that is the primary and secondary building units. The Primary Building Unit (PBU) is comprised of metal salts (transition series metals) and the Secondary Building Unit (SBU) consists of organic linkers. There has been extensive use of polymeric membranes in wastewater treatment but these membranes have major drawback which is fouling tendency. Modification of membranes by using MOFs can significantly offer a better performance for wastewater treatment with less fouling. This review paper will discuss specific class of MOFs called as Zeolite Imidazolate Frameworks (ZIFs). So far, more than 20,000 ZIFs have been developed and some of them has been utilised for the modification of mixed matrix membranes (MMMs). This happens due to different factors, most of which are connected to features & uses of the MMM, such as diffusivity, Selectivity, pore size, and stability, and others which are linked to ZIFs–polymer interaction, including the existence of its interfacial defects and its influence on performance. ZIFs generally exhibit characteristics of enormous porosity, large specific surface area, tuneable pore-size, thermal stability and chemical in-activity which all favour anti-fouling tendency.