Gold recovery from acidic wastewater using ionic viologen organic and metal–organic framework composites

Abstract

This study reports syntheses of a set of unique ionic hybrid composites to efficiently remove gold anions from acidic wastewater. The hybrid composites were easily obtained using a well-known metal–organic framework (MOF) and an ionic viologen organic framework (iVOF) that were thoroughly characterized. The highest uptake capacity recorded by iVOF-2@MOF_Comp-3 was 1053 mg g⁻¹ within three hours. This adsorbent was also able to quantitatively (>99%) remove gold species within fifteen minutes from a highly acidic (pH = 1) aqueous solution with a distribution coefficient (K_d) greater than 10⁵ mL g⁻¹. The hybrid composite adsorbent could also be recycled easily, thus fulfilling most of the criteria expected in effective adsorbents.