Electro-confinement membrane desalination by nanoporous carbon membrane

In this work, we reported a novel desalination method, electro-confinement desalination (ECMD), combining electric field and confinement effects using nanofiltration carbon membranes (CM) as the electrode. The ECMD method showed high ions rejection and high energy efficiency. It was found that the optimum potential for rejection of SO42- was -0.4 V (SCE), a steady rejection of 94.89% for SO42- being achieved in the cathode chamber when the feed concentration of Na2SO4 was 500 mg L-1 in water. To remove Na+, we set CM anode chamber to treat the effluent water from the cathode chamber. The rejection of SO42- and Na+ reached 100% and 88.86%, respectively. Besides the high removal of ions, the energy consumption was as low as 1.90 x 10(-2) KWh m(-3). The application of nanoporous CM and electric field made the desalination process concern adsorption desalination (AD), capacitive deionization (CDI) and electric enhanced confinement membrane desalination (CMD). To understand the contribution of the AD, CDI and CMD to desalination, a series of experiments were conducted. It was found that SO42- removal could be achieved 38.62% by AD, 18.50% by CDI and 80.99% by CMD, respectively. This result suggests that high desalination efficiency was stemmed from multi-effects but mainly from electro-confinement.