Enhanced adsorption of weakly ionized antibiotics on the activated carbon fiber with electrically-driven bipolar membrane reactor

Electrosorption is an effective method for extracting ionic contaminants from water systems. However, weakly ionized pollutants are difficult to be efficiently removed by electrosorption due to their electrical neutrality under pH near 7. This study proposes a novel set-up of electrically driven bipolar membrane coupled with electrosorption by activated carbon fiber, specifically designed for the removal of weakly ionized antibiotics in water. The acidic and alkaline environments provided by the electrically driven bipolar membrane promote the protonation and deprotonation of weakly ionized antibiotics. Additionally, the electric field enhances the migration ability of ionized antibiotics and the formation of electric double layer on the surface of adsorbent. Under the potential of −2.0 V (ciprofloxacin) or 2.0 V (carbamazepine and tetracycline), the adsorption capacity of the target antibiotics (10 mg L -1 ) is increased by approximately 3.18 ∼ 4.65 times compared to the open-circuit adsorption in the flow mode, and the initial effluent concentration has decreased by 91.7 %. By applying a reverse potential (2.0 V), the regeneration efficiency of active carbon fiber reaches 76.5 % after four regeneration cycles. The energy consumption of the electrosorption system is 30.99 kWh kg-TC -1 and 33.79 kWh kg-CIP -1 . This coupled system broadens the application range of electrosorption in pollutants removal.