ZnCl2 enabled synthesis of activated carbons from ion-exchange resin for efficient removal of Cu2+ ions from water via capacitive deionization

Capacitive deionization (CDI) is a promising method to remove metal contaminants in water. Herein, we report on the preparation of activated carbon from cation-exchange resin by introducing ZnCl2 via ion exchange followed by heat treatment and CO2 activation, which is evaluated for removal of Cu2+ in water via CDI technology. The results have shown that both the heat treatment and the CO2 activation are helpful to tune the pore structure of the activated carbons in terms of ions adsorption and transportation. The activated carbon prepared by heat treatment at 600 °C and CO2 activation at 750 °C, named as AC-600-750, has the highest specific surface area of 1162 m2 g−1 and a specific capacitance of 247.4 F g−1 at 50 mV−1, with a Cu2+ adsorption capacity of 77.8 mg g−1 at 1.2 V in 50 mg L−1 CuCl2 solution that is much higher than that of the commercial activated carbon. The electrosorption of Cu2+ ions over activated carbon follows a monolayer adsorption scheme, of which the kinetic can be well explained by pseudo-first-order kinetic model. The resin-based activated carbons are of potential as an electrode material for efficient removal of heavy metal from contaminated water by CDI process.