چكيده به لاتين
Capacitive deionization process has attracted a lot of attention for desalination of water as a new electrochemical technology due to low energy consumption, low environmental impact and relatively simple operation in the last decade. In this technology in which the electrodes play a main role in absorbing ions from water, need to have high surface area and hydrophilicity, high electrical and ion conductivity, and desirable electrochemical stability. For this reason in this study, the capacitive deionization electrodes which are considered as the main component of this process have been evaluated in order to water desalination. In this research, the Zinc-Benzene tricarboxylic acid-based metal-organic framework has been synthesized by solvothermal method, first. Then with X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDS), Elemental mapping, Brunaur-Emmett-Teller (BET) and Contact angle (CA) tests, the structure of metal-organic framework has been evaluated. Then a number of electrodes were prepared including an active carbon/binder (E1 electrode) and five electrodes which were contained active carbon/binder/metal-organic framework with different percentages of metal-organic framework; at this stage, the electrode that contained 6% of the metal-organic framework (E2 electrode) which its specific capacity and ion transfer resistance were 88 F g-1 and 4.9 Ω, respectively, was selected as the best electrode in the terms of electrochemical performance. Then complete characterization of E1 and E2 electrodes in order to evaluation the effect of increasing metal-organic framework to the carbon electrode was done with FTIR, FESEM, EDS, Elemental mapping and CA tests. Then by coating the electrode ink (as an active layer) on carbon cloth which was placed on a graphite sheet as the base of the electrode, E1 and E2 electrodes were evaluated in a capacitive deionization system (100 mg L-1 NaCl solution with 253.4 µS cm-1 Electrical conductivity) in three different arrangements (including the symmetrical arrangement of E1, the symmetrical arrangement of E2 and the asymmetrical arrangement of both electrodes) under optimal conditions (1.6 V and 20 mL min-1), that the best performance was achieved in the case of asymmetric use of electrodes. In this case, the salt removal capacity reached 6.3 mg g-1 that was 1.1 mg g-1 and 0.3 mg g-1 more than two other symmetrical arrangements of E1 and E2 electrodes, respectively.
Keywords: Capacitive deionization, Water desalination, Metal-organic framework, Carbon-based electrode.
