Construction of activated carbon/activated carbon fibre capacitive deionization composite electrode and its potential application in desalination of brackish water

we constructed a novel capacitive deionization carbon/carbon composite electrode-activated carbon/activated carbon fibre (AC/ACF) with low-cost and low energy consumption and high desalination efficacy, and the desalination performance and energy consumption of the electrode under different processes, such as the electrode structure, the operating voltage, and the inlet flow rate, were investigated in comparison with those of the activated carbon (AC) and the activated carbon fibre (ACF) electrodes alone and the best operating parameters of the AC/ACF electrodes were optimized. The results showed that the oxygen-containing functional groups on the surface of AC/ACF increased, and the crystal stability was enhanced; the desalination rate and energy consumption of AC/ACF increased significantly with the increase of voltage, and the optimal operating parameters of AC/ACF were obtained through the entropy value Topsis function: operating voltage of 0.8 V, flow rate of 65 mL·min⁻¹, energy consumption of 0.17 KWh·m⁻³, and desalination rate of 19.12 %. Further normalized analysis of the cost and energy consumption of the optimized process showed that the adsorption cost (0.11 $·g⁻¹) and energy consumption of the AC/ACF composite were lower (0.45 Wh·g_salt⁻¹), thus the AC/ACF material has the advantages of energy saving, low cost, and excellent desalination performance compared with other composites.