Zeolite Adsorbents for Selective Removal of Co(II) and Li(I) from Aqueous Solutions

Abstract

Cobalt and lithium are critical metals because of its shortage, difficulty of extraction and huge economic impact due to their market value. The purpose of this work is to study their selective removal from aqueous solutions in different conditions using two commercial FAU zeolites as adsorbent materials. These solids were characterized by XRD, XRF and BET analysis, to follow up of their FAU structure integrity, their Si/Al ratio, and their specific surface area evolutions through their preparation process. The kinetic study indicates that using both zeolites with a dosage of 5 g/L a 100% cobalt removal from aqueous solutions is achievable, while lithium removal is kept around 30% (separation factor of 3.33). This selectivity is important as these two metals frequently appear together in leaching solutions form, for example, ion-Li batteries. In relation to the adsorption equilibrium, cobalt adsorption presents a finite adsorption capacity while this behavior is not observed in lithium adsorption. For this reason, Langmuir model is the most adequate to represent cobalt adsorption, while lithium adsorption is better represented by Freundlich model.