Functional metal–organic frameworks as adsorbents used for water decontamination: design strategies and applications

Abstract

With the highly rapid development of urbanization and industrial manufacturing, water contaminants are becoming more varied and complicated. The decontamination of environmental water has become a significant issue in recent decades. Among various water treatment technologies, adsorption removal has become a competitive candidate. Metal–organic frameworks (MOFs) exhibit great potential as highly efficient adsorbents. Recently, diverse functionalization strategies for MOFs have been developed to obtain higher adsorption performance. The purpose of this review is to summarize recent progress in constructing functional MOFs and their applications in the adsorption of water contaminants. With the continuous development of functionalization technologies, diverse functionalization strategies of MOFs were categorized into four main types: pre-synthetic modification, post-synthetic modification, hybridization/carbonization, and adjustment of MOFs' pore size. Typical water contaminants mainly include heavy metals in the oxidized form and element form, and ionic/polar, weakly polar, and amphoteric organic compounds. Based on the similar chemical properties of each kind of contaminant, MOFs' functional sites with common adsorption mechanisms are classified. Furthermore, the modification approaches of MOFs to achieve specific functions are discussed in detail. Finally, the challenges and potential future research opportunities are proposed for MOF-based adsorbents in water decontamination fields.