Metal-organic frameworks: A new generation potential material for aqueous environmental remediation

Abstract

• Metal ion contamination is a major cause of water pollution. • MOFs displayed excellent adsorption performance towards metal ion decontamination. • Brief discussion on types, synthesis and characterisation of MOF materials. • Review of MOF-based nanoadsorbents for metal ion removal from aqueous medium. • Engineering advances and future perspective were highlighted. With the rapid increase in the human population, freshwater availability is decreasing at an alarming rate. A large amount of wastewater is generated every year due to rapid industrialization and agricultural development. Among the various organic and inorganic pollutants, metal ion contamination is a significant contributor to water pollution, which requires immediate and substantial remediation due to its high toxicity and detrimental effect on the environment and human health. Adsorption techniqueshave shown promising scope and are commonly used for water remediation and removal of metal ion pollutants. Recently, metal–organic framework (MOF), a novel three-dimensional porous and crystalline organic–inorganic cluster complex, has attracted increased attention for the adsorption of metal ion contaminants from an aqueous solution. These materials show unique properties such as high specific surface area (SSA), high and tunable porosity, flexible topology, and chemical functionality. This article compiles and reviews the recent progress in MOF-based materials as superior adsorbent materials for metal ion removal. A brief discussion of the various synthesis methods, characterization techniques, and a comparative study of the different MOF-based adsorbents and nanoadsorbents (NAs) for metal ion removal from water bodies are summarized. The effect of pH on the adsorption performance of the various MOFs and their selectivity towards specific metal ions in the presence of other metal ions in water has been discussed. The adsorption properties of the MOF-based materials are compared with those of other commonly used adsorbent materials. Finally, the review gives insight into the research gap and limitations of these MOF adsorbents in practical applications and the possible remediation techniques that can be employed for future research opportunities for advanced designing and development of cost-effective and efficient MOF for metal ion remediation.