Selective adsorption of vanadium in asymmetric capacitive deionization with resin/activated carbon composite electrodes

摘要

In this study, a novel asymmetric capacitive deionization (CDI) technology using D314/activated carbon (AC) and D860/AC composite electrodes as the anode and cathode electrodes, respectively, was proposed to enhance the adsorption and separation efficiency of vanadium (V) from complex V-containing solutions. The V adsorption capacity and separation factor of V to impurities (Al, Fe and P) augments with pH increasing from 1.2 to 1.8. The reduction rate of V and energy consumption decrease with increasing pH but improve with increasing voltage. The higher operational voltage can enhance the selectivity of asymmetric CDI ascribing to the greater influence of electric force on adsorbing impurities than on V adsorption. The adsorbed impurities and V can be effectively washed with 0.08 M H2SO4 and 3.0 M H2SO4, respectively. V can be enriched for near 3 times and the impurities can be effectively separated from the feed solution after 8 adsorption-desorption cycles. The adsorption and separation efficiency of the present research for V are higher than those of traditional CDI, indicating that asymmetric CDI is an effective and promising technique for the enhancement of V and other ions adsorption and separation. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.