The use of electrodialysis for the removal of metals from aqueous solutions

Electrodialysis (ED) is a versatile technology that can be used to treat acidic effluents containing metal species. Its ability to operate continuously, scale up, and relatively straightforward operation can solve most of the drawbacks of current technologies. Direct reuse of flow rates from metal-concentrated outlets can avoid the need for chemical addition and precipitation. Consequently, ED emerges as a technology with enormous growth potential to concentrate, separate and selectively recover metals from acidic effluents. The study investigated the ED use for the removal of Fe2 + , Mn2 + , and Zn2 + ions from a synthetic effluent. The experimental results revealed the influence of the diluted solution composition on the limit current density values. The affinity of ion exchange membranes towards specific ions was determined, with Mn2 + showing the highest affinity and preferential retention. The efficiency of the process was affected by scaling on the membranes, particularly in the presence of Fe2 + . Cleaning with 10% HNO₃ was found to be more effective in removing ions from the membranes. The experiments consistently achieved high percentages of ionic removal (> 99%) and demineralization rates (> 95%), demonstrating the efficiency of electrodialysis. The migration of ions towards the concentrated solution was observed over time, while minimal passage to the electrolyte occurred. Overall, electrodialysis exhibited promising potential for the treatment of metal-contaminated effluents, providing effective demineralization and high percentages of ionic removal.