Nitrogen-rich covalent organic polymer-hybridized CuFe2O4-based magnetic nanoparticles for efficient iodine adsorption and Cr(VI) reduction

In this study, a magnetic covalent organic polymer nanohybrid, CuFe2O4@CGP, was prepared by a reaction between cyanuric chloride and guanidinium chloride in the presence of CuFe2O4, and fully characterized. The CuFe2O4@CGP nanohybrid showed promising activity for the adsorption of I-2 in cyclohexane compared to previous works with a theoretical maximum adsorption capacity (Qmax) of 769.23 mg/g and a removal efficiency of 98.31 % of I-2 which was significantly higher than that of bare CuFe2O4 due to a conjugated It-electron system, N-H-containing and surface -OH groups. The pseudo-second-order kinetic model and the Langmuir model provided a better fit for I-2 adsorption over CuFe2O4@CGP. The process of I-2 adsorption on the CuFe2O4@CGP surface was also investigated by quantum chemical calculations. Furthermore, the CuFe2O4@CGP acted as a bifunctional catalyst for the efficient decomposition of HCOOH to H2 and CO2 and the reduction of highly toxic Cr(VI) to low-toxic Cr(III) in an aqueous medium. The CuFe2O4@CGP nanohybrid was more efficient than the bare CuFe2O4 NPs with a higher rate constant (0.36 min- 1) and activity parameter (0.30 s(-1) g(-1)). The CuFe2O4@CGP nanohybrid showed recoverability and reusability up to six- and five times for the adsorption/ desorption process and reduction, respectively.