Effective synthesis and characterization of citric acid cross-linking of modified ferrous metal-organic framework and chitosan nanocomposite sponge for Th(IV) elimination: Adsorption isotherms, kinetic analysis, and optimization by Box-Behnken design

• Published in: International journal of biological macromolecules 2024-11, Vol.281 (Pt 1), p.136194, Article 136194
• Main Authors: Al-Hazmi, Ghaferah H., Albedair, Lamia A., Alatawi, Raedah A.S., Alsuhaibani, Amnah Mohammed, Bukhari, Abeer Abdulaziz H., El-Bindary, Ashraf A.
• Format: Article
• Language: English
• Subjects: Adsorption; Box-Behnken design; Chitosan - chemistry; Citric Acid - chemistry; Hydrogen-Ion Concentration; Isotherm; Kinetics; Mechanism of interaction; Metal-Organic Frameworks - chemistry; Nanocomposites - chemistry; NH2-Fe(II)-MOF@CSC; Radioactive thorium (IV); Temperature; Thorium - chemistry; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water Purification - methods
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.136194

This research presents a novel nanocomposite of ferrous metal-organic framework (Fe(II)-MOF) that has been encapsulated with chitosan matrix, leading to the development of a new adsorbent referred to as NH2-Fe(II)-MOF@CSC composite sponge. This composite sponge has shown effectiveness in removing radioactive thorium (IV) contamination from water sources. The adsorbent underwent characterization using techniques including FTIR, PXRD, BET analysis, and SEM. The adsorbent has a high surface area of 1360.8 m2/g. The most effective conditions for adsorbing Th(IV) were found to be a pH of 5, using 0.02 g of adsorbent dose per 25 mL, and maintaining a contact time of 100 min. The composite sponge demonstrated an impressive maximum adsorption capacity of 618.8 mg/g for Th(IV). The adsorption process was fitted to Langmuir isothermally and kinetically fitted to pseudo-second-order. Nonetheless, the relatively low adsorption energy of 6.22 kJ/mol suggests that the main adsorption mechanism is physisorption, which is marked by weaker van der Waals forces. This discovery could have implications for the material's potential for easy regeneration. In the analysis of the influence of temperature on the adsorption of Th(IV), it was discovered that the adsorption process is endothermic because the positive ΔHo value was 24.48 kJ.mol−1. Furthermore, a positive ΔSo value of 87.46 J.mol−1 K−1 suggests the existence of disorder at the solid-solution interface. Conversely, a temperature rise resulted in a higher negatively charged ΔGo, indicating that the adsorption process is spontaneous. The research also examined the mechanism of interaction, such as π-π interaction, hydrogen bonding, pore filling, and electrostatic interaction. It was noted that the adsorbent can be efficiently used for a maximum of six cycles, demonstrating its economic viability. The adsorption outcomes were optimized using the Box Behnken design (BBD). [Display omitted] •Synthesis and characterization of novel NH2-Fe(II)-MOF@CSC composite sponge.•Highly efficient adsorption and removal of Th(IV) the adsorption capacity was 618.8 mg/g).•The adsorption process was fitted to Langmuir isothermally and to pseudo-second-order kinetically•The adsorption results were optimized via BOX-Benkhen design.