Adsorption of rubidium ion from aqueous solution by surface ion imprinted materials

Abstract

A new type of rubidium ion-imprinted polymer has been synthesized by the surface-imprinting technique using methacrylic acid as the functional monomer, the rubidium ion as the template, methanol as the solvent, and silica as a carrier. Ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile were used as acrosslinker and an initiator, respectively. In addition, based on the macrocyclic effect of crown ethers, the 18-crown-6 ligand was introduced as a ligand to fix the template ions better. Scanning electron microscopy, Zeta-potential analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were performed to characterize the ion-imprinted polymer. The effects of the preparation and adsorption conditions on the adsorption performance of the rubidium ion-imprinted polymer were investigated. The results indicated that the rubidium ion-imprinted polymer has high selectivity and faster kinetics than other adsorbents, with an equilibrium adsorption capacity of 200.19 mg·g −1 at 298 K within 25 min. The sorption isotherm was well described by the Freundlich isotherm model, while the adsorption kinetics fitted the pseudo-second-order kinetic model. Consecutive adsorption–desorption experiments showed that the ion-imprinted polymer had good chemical stability and reusability.