Advances In Green Synthesis Of Mixed-Metal Metal Organic Frameworks For Wastewater Remediation

Abstract

Water pollution due to various pollutants is a serious global problem for environment. Heavy metals, dyes and pharmaceuticals are the main pollutants of water. Traditional techniques are insufficient in removing these complex and persistent pollutants, necessitating the development of advanced materials for the efficient decontamination of water. Metal organic frameworks are considered as advanced materials owed to their superior structural and physiochemical properties than other conventional materials. Mixed metal MOFs have shown enhanced properties than monometallic MOFs due to synergistic effect of metal centers in the mixed metal MOFs. However, conventional MOFs synthesis techniques often involve elevated temperature and pressure, high energy requirement and hazardous solvents which can reduce the environmental sustainability. Green synthesis can provide promising approaches to synthesize mixed-metal MOFs (MM-MOFs) with enhanced physicochemical properties from the synergistic effect of metals. This review provides recent advances in green synthesis of mixed-metal MOFs including microwave-assisted, ultrasonication, mechanochemical and aqueous and room-temperature synthesis. The structural features and advantages of mixed-metal MOFs along with their application in wastewater remediation, particularly for the removal of dyes, heavy metals and pharmaceuticals are discussed. Finally, current challenges are discussed along with future research directions toward sustainable and practical wastewater treatment.