Separation and recovery of indium from solution in a sulfite-sulfuric acid system

In this investigation, to separate and recover indium (In), the adsorption and desorption characteristics of indium in the sulfite-sulfuric acid system using IRA-900 resin and the adsorption mechanism were explored. When so-dium sulfite and sulfuric acid concentrations were 0.5 mol/L, IRA-900 resin exhibited the best adsorption selectivity to indium, with an adsorption capacity of 95.56 mg/g(318 K), while the adsorption capacities of Al, Sr, Fe, Zn and Cu were weak. In(III) adsorption by resin conforms to the second-order kinetic model, and the Langmuir model is more suitable for adsorption. In desorption experiments, 2 mol/L hydrochloric acid was selected as the desorption agent, with a desorption rate of 82.39 %. FT-IR (Fourier-transform infrared spec-troscopy), SEM-EDS (Scanning electron microscopy with energy dispersive spectroscopy), XPS (X-ray photo-electron spectroscopy) and elemental analysis results indicated that the adsorption mechanism of indium could be attributed to the formation of an anionic complex between In3+ and HSO3-/HSO4-, which could be exchanged with Cl- on the resin to adsorb the metal ions. In addition, the column experiment could efficiently separate indium from simulated indium-containing solution. In(III) recovery yield was about 99.6%, indicating its effective separation and recovery from ITO (Indium tin oxide) film.