Recovery of Germanium from Aqueous Solutions by Ion-Exchange Extraction of Its Catechol Complex

The paper is concerned with the recovery of germanium from dilute aqueous solutions. The method is based on the sorption of the selective complex formed by catechol with germanium onto low-cost anionic resins. Experimental investigations were undertaken using conventional quaternary ammonium macroporous resins: Amberlite IRA-900 and IRA-958. The influence of pH, metal concentration, and amounts of resin and catechol on the sorption capacity were investigated. For a proper set of experiments, a statistical technique such as a response surface methodology (RSM) has been used. For the investigation of the exchange equilibrium, the experimental data were analyzed using the Langmuir, Freundlich and Dubinin−Radushkevich equations, the Freundlich isotherm in general constituting a better fit. The uptake of the germanium complex by the ion-exchange resins was reversed by acid and neutral solutions. The results obtained showed better performance for IRA-900 than IRA-958, measured in terms of global recovery yields...