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

Fe 3 O 4 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)/ ⁠ , 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. Magnetic surface ion-imprinted polymer was synthesized for rapid and selective removal Mo(VI) from aqueous solution. The effects of pH value, contact time and initial concentration on the adsorption process were investigated. Mo(VI) adsorption followed the pseudo-second-order kinetics and Langmuir isotherm model. Magnetic surface ion-imprinted polymer showed high selectivity for Mo(VI) in the presence of competitive ions.