Synthesis of coated solvent impregnated resin for the adsorption of indium (III)

Coated solvent impregnated resins (CSIRs) had been prepared by the formation of PVA–boric acid protective layer on solvent impregnated resins (SIRs) containing 2-ethylhexyl phosphoric acid mono (2-ethylhexyl) ester (EHEHPA). The CSIRs were characterized by scanning electron microscopy, thermogravimetric analysis and FTIR analysis. The adsorption behavior for indium (III) was carried out with the CSIRs by batch and column method. Various parameters affecting the adsorption of indium (III) such as solution pH, ionic strength, contact time, indium ion concentration and flow rate were studied, respectively. The optimal pH for the adsorption of indium ion was found to be 1.5 in the sulfuric acid system. The indium (III) loaded on CSIRs could be effectively eluted by hydrochloric acid solution (0.5–2.0 mol L− 1), and the recovery was over 98.9%. The sorption isotherms were found to fit with Langmuir and Freundlich isotherms, respectively. The kinetics data indicated that the adsorption process of indium (III) with CSIRs followed Lagergren first order rate model. Separation of indium (III) from binary solution was also carried out successfully. The performance of the CSIRs nearly remained constant while the uncoated solvent impregnated resins (UCSIRs) rapidly lost the capacity after seven times recycling.