The results showed that the brine flow rate was the most significant factor affecting the desalination efficiency of the aqueous and ionic liquid FCDI systems (p < 0.0001). The optimal process conditions for the ionic liquid system fitted by the model were as follows: 6.6 wt% activated carbon content in the electrode slurry, a brine flow rate of 45 mL/min, an initial brine concentration of 1 g/L, and an electrolyte ratio of N, N-Dimethylformamide/1-ethyl-3-methylimidazolium tetrafluoroborate = 3.
The desalination effect of FCDI under the above optimal process conditions was up to 99.739 % at a voltage of 3.5 V, and the water-desalting efficiency was still maintained at over 95 % after 20 cycles. Compared with the aqueous electrolyte, using ionic liquid electrolytes significantly improves the desalination rate and cycling stability, and this study provides new ideas and methods for developing and applying high-performance electrolytes in FCDI systems.