The crisis of excessive increase in CO₂ emissions has quickly become a serious issue and requires low-cost and bio-compatible solutions. The employee of membrane technology for CO₂ gas separation has garnered significant interest among researchers. However, this method encounters challenges related to selectivity and permeability. Therefore, modifying and reinforcing the polymer membranes to improve gas separation performance seems essential. Among the various methods for polymer membrane modification, modification with magnesium-based fillers to prepare a mixed matrix membrane (MMM) is considered an efficient method. Owing to magnesium metal’s low weight, low density, high strength, and good selectivity, magnesium-based materials (Mg-based materials) have more porosity, higher available surface area, more adsorption sites, lighter weight, and more gas absorption tendency than other fillers, which makes them an attractive choice for the preparation of gas separation MMMs. This research deals with the introduction of Mg-based materials, various methods of synthesis of Mg-based materials, different methods of introducing Mg-based materials into the membrane matrix, and their effect on the performance of MMMs in CO₂ gas separation applications. Therefore, this review can provide researchers with light horizons in using the high potential of Mg-based materials as efficient fillers in MMMs to achieve excellent permeability and selectivity and generally improve their performance in CO₂ gas separation applications.

Magnesium (Mg) is a widely used and attractive metal, known for its unique physical and chemical properties, and it has been employed in the manufacture of many practical materials. Layered Double Hydroxides (LDHs), particularly Mg-based LDHs, rank among the most prevalent two-dimensional materials utilized in separation processes, which include adsorption, extraction, and membrane technology. The high popularity of Mg-based LDHs in separation applications can be attributed to their properties, such as excellent hydrophilicity, high surface area, ion exchangeability, and adjustable interlayer space. Currently, polymer membranes play a pivotal role in semi-industrial and industrial separation processes. Consequently, the development of polymer membranes and the mitigation of their limitations have emerged as compelling topics for researchers. Several methods exist to enhance the separation performance and anti-fouling properties of polymer membranes. Among these, incorporating additives into the membrane polymer matrix stands out as a cost-effective, straightforward, readily available, and efficient approach. The use of Mg-based LDHs, either in combination with other materials or as a standalone additive in the polymer membrane matrix, represents a promising strategy to bolster the separation and anti-fouling efficacy of flat sheet mixed matrix polymer membranes. This review highlights Mg-based LDHs as high-potential additives designed to refine flat sheet mixed matrix polymer membranes for applications in wastewater treatment and brackish water desalination.