Stoichiometry, isotherms and kinetics of adsorption of In(III) on Cyanex 923 impregnated HZ830 resin from hydrochloric acid solutions

Abstract

A novel solvent-impregnated resin (SIR) with trialkylphosphate Cyanex 923 as extractants and macroporous resin HZ830 as substrate was prepared to adsorb In(III) from HCl solutions. The effects of HCl concentration on adsorption were investigated within the range of 0.5 to 7molL−1, and results showed that adsorption capacity was greatest at 2molL−1 HCl. The adsorption mechanism of In(III) in chloride medium suggested that In(III) was apt to be adsorbed as a neutral species InCl3. As the anionic species InCl4− it tended to be adsorbed in the form of ion pairs combined with protons. The extraction stoichiometry of In (III) with SIR was studied, and the extracted species were found to be InCl3·nL and HInCl4·nL (n=2, 3). The isothermal adsorption of In(III) fit the Langmuir model. Kinetic data indicated that the adsorption process was consistent with a pseudo second order model, and the sorption rate was mainly controlled by an intraparticle diffusion step. A column experiment showed that In(III) could be eluted from SIR with 2molL−1 sulfuric acid, and the SIR showed good stability and reusability after five adsorption-elution cycles. When the SIR was applied for In(III) adsorption from waste liquid crystal display (LCD) leaching solution containing 102.15mgL−1 In(III), the adsorption efficiency exceeded 90% with 0.30g adsorbent.