Ordered mesoporous carbons synthesized by a modified sol–gel process for electrosorptive removal of sodium chloride

Capacitive deionization (CDI) represents an alternative process to remove the ions from the brackish water. In this study two series of ordered mesoporous carbons (OMCs) that demonstrated the potential use for capacitive desalination have been synthesized by a modified sol–gel process involving nickel salts. It was shown that the preferred formation of crown-ether type complexes between nickel ions and triblock copolymers resulted in higher BET surface area and smaller mesopores. As the electrode materials for CDI, OMC obtained by the addition of NiSO4 · 6H2O exhibited best electrochemical performance compared with other OMCs and a commercial activated carbon either in 0.1 M NaCl solution or in 0.0008 M NaCl solution, plus the amount of adsorbed ions measured by a flow through apparatus reached 15.9 μmol g−1 and the ions could be fully released into the solution. The excellent electrosorption desalination performance of OMC obtained by the addition of NiSO4 · 6H2O was ascribed to its high BET surface area of 1491 m2 g−1 and ordered mesopores of 3.7 nm. Based on these results, it is deduced that the modified sol–gel process might be a potential method of obtaining the excellent electrode materials for CDI.