Selective and rapid removal of Mo(VI) from water using functionalized Fe3O4-based Mo(VI) ion-imprinted polymer

Fe3O4 nanoparticles-based magnetic Mo(VI) surface ion-imprinted polymer (Mo(VI)-MIIP) was elaborated employing 4-vinyl pyridine as a functional monomer. The adsorbent preparation was confirmed by Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, vibrating sample magnetometer, thermogravimetric analysis, and surface area analysis. Batch adsorption experiments showed that the maximum adsorption capacity of Mo(VI)-MIIP was 296.40 mg g(-1) at pH 3, while that of the magnetic non-imprinted polymer (MNIP) was only 147.10 mg g(-1). The adsorption isotherm model was well fitted by the Langmuir isotherm model. The adsorption experiments revealed that Mo(VI)-MIIP reached adsorption equilibrium within 30 min, and the kinetics data fitting showed that the pseudo-second-order kinetics model suitably described the adsorption process. Mo(VI)-MIIP exhibited an excellent adsorption selectivity to Mo(VI) in binary mixtures of Mo(VI)/Cr(VI), Mo(VI)/Cu(II), Mo(VI)/H(2)PO4(4)(-), Mo(VI)/Zn(II), and Mo(VI)/I-, with relative selectivity coefficients toward MNIP of 13.71, 30.27, 20.01, 23.53, and 15.89, respectively. After six consecutive adsorption-desorption cycles, the adsorption capacity of Mo(VI)-MIIP decreased by 9.5% (from 228.4 mg g(-1) to 206.7 mg g(-1) at initial Mo(VI) concentration of 250 mg L-1), demonstrating its reusability.

Automated summary

A magnetic Mo(VI) surface ion-imprinted polymer (Mo(VI)-MIIP) based on Fe3O4 nanoparticles was successfully prepared and characterized, showing high adsorption capacity and selectivity for Mo(VI) in various binary mixtures. The material exhibited excellent performance in adsorption experiments and demonstrated good reusability after multiple cycles.