Application of Ion-Exchange Membranes With Graphene Oxide in the Removal of Metal Ions Using the Electrodialysis Process.

Abstract

The collapse of the Fundão dam in Mariana, Minas Gerais, Brazil, affected the Gualaxo do Norte, Do Carmo, and Doce rivers, as well as part of the Brazilian coastline. Studies indicate the presence of metallic ions along the route and the need to treat water for human consumption. These studies also show the impact on the surrounding fauna and flora. Electrodialysis and anion-exchange membranes (AEM) are emerging as an alternative methods for removing metallic ions. This study aimed to use an electrodialysis cell with heterogeneous ion-exchange membranes incorporating resins and a graphene oxide (GO) solution at proportions of 5.0% and 2.5% (m/m), respectively. Tests were carried out to remove Mn²⁺ ions in a synthetic effluent using an electrodialysis cell. More than 90% of the diluted solution was removed using polysulfone membranes with GO, both before and after cleaning. The removal percentages of Mn²⁺ ions exceeded 94% for the ion-exchange membranes and 95% for the membranes with GO, even after regeneration. The membranes were regenerated with 0.1 M NaCl and HCl solutions and then reapplied to the electrodialysis process. Removal rates exceeded 90% for membranes regenerated with the addition of GO. Samples were collected and characterized for suspended solids, with concentrations of 0.23 and 0.13 g/L in the Gualaxo do Norte and Doce rivers, respectively. Metallic ion concentrations were 0.67 and 0.42 g/L for Cr⁶⁺, 239.18 and 83.96 mg/L for Fe²⁺, and 12.39 and 2.39 mg/L for Mn²⁺ in the Gualaxo do Norte and Doce rivers, respectively. Using samples collected from the rivers in an electrodialysis cell with polyethersulfone membranes and 2.5% graphene oxide added showed removal rates of 72.8%, 91.3%, and 85.7% for chromium, iron, and manganese, respectively. Adding GO proved promising for producing heterogeneous ion-exchange membranes, showing potential for metal-ion removal applications in different contaminated effluents.