Enhanced adsorption of ionizable antibiotics on activated carbon fiber under electrochemical assistance in continuous-flow modes.

Ionizable antibiotics have attracted serious concerns because of their variable dissociation forms and thereby rendering unique toxicity and microorganism resistance. Developing an efficient and environmentally friendly method for removing these micropollutants from environmental media remains very challenging. Here, electro-assisted adsorption onto activated carbon fiber in continuous-flow mode was used to remove three ionizable antibiotics, sulfadimethoxine (SDM), ciprofloxacin (CIP), and clarithromycin (CLA), from water. Benefiting from strengthened electrostatic interactions, the adsorption capacities for the target antibiotics (10 mg/L) in flow mode (70.9-202.2 mg/g) increased by ∼5 times under a potential of 1.0 V (SDM) or -1.0 V (CIP and CLA) relative to those of open circuit (OC) adsorption. Meanwhile, effluent concentration decreased from >100 μg/L to 9.6 μg/L with removal efficiency increasing from 99.0% to 99.9%. Moreover, high recovery efficiency of ACF up to 96.35 ± 0.65% was achieved by imposing a reverse potential (-1.0 V) relative to that used for SDM adsorption. In addition, trace levels of antibiotics (364-580 ng/L) in surface water could be removed effectively to achieve low effluent concentration (0.4-1.2 ng/L) and high removal efficiency (99.9%) upon treating up to ∼1560 bed volumes (BVs), demonstrating the potential of electro-assisted adsorption for practical application in water treatment.