Fe₃O₄‑Based Melamine-Rich Covalent Organic Polymer for Simultaneous Removal of Auramine O and Rhodamine B

The present study focused on utilizing the advantages of porous covalent organic frameworks by preparing them in a usable magnetite support form with Fe₃O₄ nanoparticles using the solvothermal method. Functionalized Fe₃O₄-based melamine-rich covalent organic polymer (COP) was prepared and identified using different physicochemical techniques, such as Fourier-transform infrared, X-ray diffraction, field emission scanning electron microscopy, Brunauer–Emmett–Teller analysis, and vibrating sample magnetometer analysis. Then, the constructed compound was utilized to simultaneously remove auramine O (AO) and rhodamine B (RB) as cationic dyes by the interactions of electrostatic attraction, H-bonding, Lewis acid–base interaction, and π–π stacking from an aqueous solution. The substantial variables such as pH, Fe₃O₄/COP mass, AO and RB concentrations, and sonication time were inspected, and the optimized conditions were found to be 6.5, 12 mg, 10 mg/L, and 4 min, respectively. The fitting of experimental equilibrium data to various isotherm models reveals the applicability and suitability of the Langmuir model. The adsorption capacities for simultaneous removal of AO and RB were 107.11 and 131.23 mg/g, respectively. The kinetic model’s examinations reveal that the kinetics of the process was pseudo-second-order. The thermodynamic result indicates the endothermic and automatic nature.