Improvement in capacitive deionization function of activated carbon cloth by titania modification

Activated carbon cloth (ACC) was modified by the reaction between polar groups on its surface and metal alkoxides of titanium, silicon, aluminum and zirconium to enhance its capacitive deionization (CDI) performance. Incorporated state of metals and surface property of modified ACC were deduced from surface analysis results obtained using FE-SEM, XRD, XPS and zeta-potential meter. Titania was highly dispersed on the ACC surface with tetrahedral coordination, and the incorporated titania was effective to decrease physical adsorption of NaCl and to increase electric field adsorption, resulting in a significant enhancement of CDI performance. The negligible contribution of silica, alumina and zirconia modifications suggested that the small oxidation-reduction potential of titania was responsible for the enhancement of the electric field adsorption. Reversibility of adsorption and desorption operation on titania-modified ACC were also discussed relating to its CDI function.