Performance comparison and energy consumption analysis of capacitive deionization and membrane capacitive deionization processes

In this paper, graphite cloths were used as electrode materials to fabricate the capacitive deionization (CDI) cell and the ion-exchange membranes were introduced in the CDI cell to assemble the membrane capacitive deionization (MCDI) module. The desalination performances of the MCDI and the CDI cells were investigated under different working voltages and feed concentrations and assessed by adsorption capacity and specific energy consumption. The experimental results indicated that the introduction of the ion exchange membranes could effectively prevent the “co-ion” effect in the CDI and the current efficiency of MCDI was up to four times of the CDI. Under the experimental conditions, the adsorption capacity of MCDI is much higher than that of the CDI and also its specific energy consumption was dramatically reduced indicating the comprehensive economical advantage of MCDI technology. •An innovative control strategy was adopted to realize the cyclic operation of the system.•The “co-ion” effect in CDI was revealed and monitored through outlet stream conductivity variations.•The MCDI and CDI processes were assessed in terms of current efficiency and specific energy consumption.•The MCDI was significantly superior to CDI in current efficiency and specific energy consumption.