Extraction of Rb(I) Ions from Aqueous Solution Using Novel Imprinting Materials

A new type of Rb(I) ion imprinting material was prepared with methacrylic acid as functional monomer, Rb(I) ion as template, and methanol/acetonitrile as solvent. The polymerization reaction was initiated by N,N-azobis(isobutyronitrile) (AIBN) with the cross-linking by ethylene glycol dimethacrylate (EGDMA). In addition, benzo-12-crown-4-ether (B12C4) was introduced as a ligand to fix the template ions better. Scanning electron microscope, Zeta potential analysis, Fourier transform infrared spectrum, thermogravimetric analysis, and energy dispersive spectra were used for characterization of the imprinted polymer. Effects of preparation and adsorption conditions on adsorption performances of Rb(I) ion-imprinted polymers (IIPs) were investigated. The imprinted polymer had fast adsorption kinetics (reaching equilibrium within 15 min) and high maximum adsorption capacity (129.9 mg·g–1) at pH 9.5. Besides, the adsorption process conformed to pseudo-second-order kinetic and Freundlich isotherm models. Moreover, the prepared Rb(I)-IIPs showed high selectivity for Rb(I) ions. The results of eight repeated cycles of adsorption–desorption demonstrated that the prepared Rb(I)-IIPs had good stability and reusability.