Preparation of a tetraethylenepentamine grafted magnetic chitosan bead for adsorption of Re(vii) from aqueous solutions

A cross-linked magnetic chitosan bead (MCB) and tetraethylenepentamine grafted magnetic chitosan bead (TMCB) were synthesized using the water/oil (W/O) emulsion cross-linking method and characterized using scanning electron microscopy (SEM), vibrating-sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The saturation magnetization and remanent magnetization of TMCB were 7.09 emu g⁻¹ and 0.834 emu g⁻¹, respectively, illustrating the superparamagnetic properties of the prepared TMCB. The adsorption properties of MCB and TMCB for the removal of rare metal rhenium from acidic effluents were evaluated. Kinetic experimental data fit well with the pseudo-second-order model, and the adsorption isotherms were better fitted with the Langmuir model. The maximum adsorption capacities of Re(VII) as obtained from the Langmuir model were 224.50 and 257.61 mg g⁻¹ for MCB and TMCB, respectively, at pH 3 and 30 °C. Thermodynamic analysis revealed that the adsorption process is both spontaneous and exothermic. Regeneration experiments were conducted using 2 M NaCl, and TMCB maintained good adsorption and desorption performance after five regeneration cycles, indicating a promising material for the recovery of rhenium from acidic industrial effluents.