Covalent organic frameworks and metal–organic frameworks for sustainable adsorptive removal/extraction of dirty dozen chemicals: A review

Abstract

Dirty dozen chemicals (DDCs) are a group of 12 extremely toxic chemicals that were recognized at the Stockholm convention in 2001 for their severe impact on the ecosystem and human health. Despite the embargo and restraint placed on DDCs usage, these chemicals continue to find their way into the ecosystem because they are still secretly or openly applied by many nations, especially in African regions. Moreover, DDCs can still be perceived where they have been employed previously before the Stockholm convention treaty due to their persistent profile. This study aimed to critically review original works directed toward the removal of various dirty dozen chemicals using covalent and metal–organic frameworks (COFs and MOFs). Specifically, in this study, various COFs/MOFs and their composites with remarkably tailored adsorptive profiles are evaluated for their adsorption efficiency for different DDCs. In addition, the effect of various operating parameters that are of importance to environmentalists and various stakeholders for optimization purposes was empirically discussed. This review also fills knowledge vacuums about the COF/MOF-DDCs adsorption process, offers insights into their reusability potential, fundamental mechanism, isotherm, and kinetic modeling, and offers a framework for future studies. Findings from this study revealed that COF and MOF have high DDC removal capacity and reusability potential attributed to their admirable porosity and the existence of a plethora of oxygen-rich functional groups that allow for better interactions with DDCs through chelation, halogen bonding, H-bonding, and π-π interactions and stacking. This points to the upscaling potential of this remediation technique. Future researchers need to direct more efforts to the use of density functional theory for mechanism interpretation, exploration of hybrid technology, cost analysis, scalability, isotherm, thermodynamics, adsorption, and desorption kinetic modeling.