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 ZnCl 2 via ion exchange followed by heat treatment and CO 2 activation, which is evaluated for removal of Cu 2+ in water via CDI technology. The results have shown that both the heat treatment and the CO 2 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 CO 2 activation at 750 °C, named as AC-600-750, has the highest specific surface area of 1162 m 2  g −1 and a specific capacitance of 247.4 F g −1 at 50 mV −1 , with a Cu 2+ adsorption capacity of 77.8 mg g −1 at 1.2 V in 50 mg L −1 CuCl 2 solution that is much higher than that of the commercial activated carbon. The electrosorption of Cu 2+ 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.