Electrosorptive removal and recovery of phosphorus via flow electrode capacitive deionization using carbon black and activated carbon electrodes

ABSTRACT In this study, activated carbon (AC) and carbon black (CB) were tested as flowable electrode (FE) materials for removing and recovering phosphorus from synthetic wastewater. Experiments used the flow capacitive deionization (FCDI) system under short-circuited closed-cycle (SCC) conditions. Phosphorus removal was evaluated under different operational parameters, including applied voltage, solution flow rate, solution pH, phosphorus concentration, and electrode dosage. Applied voltage and solution pH had the greatest impact on removal efficiency among other parameters. Maximum phosphorus removal efficiencies were 83.74 ± 1.30% with AC and 90.45 ± 1.12% with CB, corresponding to adsorption capacities of 8.76 mg/g and 9.26 mg/g. Physisorption on carbon particles was negligible compared to electrosorption. Electrode regeneration by short-circuiting achieved recovery efficiencies of 68.06 ± 0.46% for AC and 85.46 ± 0.74% for CB. Generally, CB performed better than AC in both removal and recovery, highlighting its promise as an effective FE material. These results exhibit the potential of FCDI as a sustainable technology for phosphorus-rich wastewater treatment and nutrient recovery.