Significantly improved antibiotics removal and material utilization in novel electrodialysis integrated with nanostructured carbon microspheres

Due to the limited effectiveness of electrodialysis (ED) in removing organic micro-contaminants, various carbon-based adsorption materials can be utilized to enhance the overall removal performance. Integrating adsorption materials into the ED process may improve removal efficiency and material utilization under the influence of electric field. In this study, uniformly sized activated carbon microspheres (ACMs) with bimodal pore structures were packed into the dilute compartment of an ED system to remove antibiotics while desalting brackish water. The results demonstrated that the applied electric field significantly enhanced the removal of sulfadiazine and chlortetracycline from brackish water, and increased their adsorption capacities in the ACMs by 120.7 % and 386.3 %, respectively, without compromising desalting efficiency. The application of frequent electrode reversal, a routine practice in ED, further improved the removal efficiency by around 32 %, indicating more efficient utilization of the micropores in ACMs. Although the addition of humic acid reduced adsorption efficiency, frequent electrode reversal mitigated this adverse impact, highlighting its role in resisting fouling caused by humic-like substances. A comparative analysis between mathematical modeling and experimental data revealed that the electric field promoted the shuttling of antibiotics in mesoporous channels, thereby enhancing the adsorption by overcoming resistance between the micro- and mesopores. The long-term experiment demonstrated consistently high removal efficiencies and long-term stability of ACMs in the system. Overall, this study shows that integrating ACMs into the ED system and applying frequent electrode reversal are promising in the treatment of brackish water containing micro-contaminants.