Competitive gallium and indium adsorption from wastewaters on low cost chabazite

Abstract

The paper describes the gallium and indium adsorption from aqueous solutions employing chabazite as adsorbent. Kinetic and isotherm adsorption experiments in monometallic solutions were carried out to ascertain the adsorption mechanisms. The obtained results showed that the adsorption of Ga (III) onto chabazite was properly described by Sips model while indium adsorption is well described by Freundlich model. Competitive adsorption experiments showed that chabazite had more affinity towards gallium than towards indium due to, according to the speciation diagrams, in the case of gallium the predominant specie in solution is GaOH2+, while in the case of indium, the main ionic specie is In3+. However, the most outstanding conclusion is that it is possible to remove both metals from the aqueous media, employing a relatively high chabazite dosage while with a low chabazite dosage (1 g/L) it is possible to selectively retain gallium in solid, remaining indium ions in the solution.