A review on covalent organic frameworks with Mult-site functional groups as superior adsorbents for adsorptive sequestration of radio-contaminants

• Published in: Journal of organometallic chemistry 2024-07, Vol.1015, p.123226, Article 123226
• Main Authors: Emmanuel, Stephen Sunday, Adesibikan, Ademidun Adeola, Bayode, Ajibola A., Olawoyin, Christopher Olusola, Isukuru, Efe Jeffery, Raji, Oluwasegun Yusuf
• Format: Article
• Language: English
• Subjects: Adsorption isotherm; Covalent organic frameworks (COFs); Desorption; Radio-pollutants; Sustainable development goals (SDGs)
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2024.123226

•Covalent organic frameworks (COF) have high reusability (up to 8 cycles) potential.•COFs showed an uptake capacity of 41.79 - >5000 mg/g for various radio-pollutants.•Complexation via oxygenated functional groups is the key COF-radio-pollutants interaction.•Langmuir and pseudo-2nd-order model suggesting monolayer adsorption is the best fit.•Future research can examine the scalability and cost analysis of COF. Radioactive contamination has become one of the most significant environmental issues due to the steady advancement of nuclear technology and nuclear engineering's application scope. The presence of radio-contaminants in water, the lifeblood of the planet is a dark stain on the canvas of the ecosystem, marring its vitality. Interestingly, in recent decades, covalent organic frameworks (COF) have received laudable applause among the research community and have been recognized as one of the sustainable adsorbing porous functional materials to tackle this menace owing to eco-friendliness, improved surface properties, flexible topological connectivity, long-term stability, and tunable structure. This review fills in information gaps about the COF-radio-contaminant adsorption process, provides insights into its underlying mechanism, adsorption kinectic, and isotherm modeling, and provides a framework for future research. Notably, the maximum radiocontaminant uptake reaches 2362.4 mg/g, ascribed to COFs excellent porosity and the presence of several oxygenated surface functionalities. The majority of COF-radio-contaminants interactions occur through complexation, electrostatic, H-bonding, and π–π interactions. The isotherm modeling for radio-contaminant uptake indicates that Langmuir is the best fit, suggesting monolayer adsorption operation. The kinetics of adsorption were well-modeled by the pseudo-second-order kinetic equation, which demonstrated that the concentration of radio-contaminant in the aqueous phase and the number of COF active sites both affect the rate of adsorption. According to thermodynamic modeling, adsorptive uptake of radio-contaminant by COF is usually spontaneous. The majority of the COFs are reusable for more than five cycles, and radio-contaminants may be desorbed from them back into the aqueous phase over a broad range of eluents. Future research might examine the scalability and cost analysis of the COF adsorption approach for radio-contaminant elimination. [Display omitted]