Preparation Of Mixed Metal Oxide Films Electrode And Its Capacitive Deionization Property

Hydrotalcites not only have important application in adsorption water treatment, but also have extensive research in the super capacitor. In the study, NiAl metal oxide(NiAl-MMO), NiCoAl-MMO, NiAl-MMO/Pd films, that were the calcined products of hydrotalcite-like compounds, were grown on the surface of foam nickel by a coprecipitation method and then an in-situ hydrothermal method. The structure, compose and surface morphology of NiAl-MMO, NiCoAl-MMO, NiAl-MMO/Pd films electrodes were analyzed by scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD). The result indicated that the NiAl-MMO, NiCoAl-MMO, NiAl-MMO/Pd films electrodes were synthesized successfully on the surface of foam nickel.The electrochemical perdormance of NiAl-MMO, NiCoAl-MMO, NiAl-MMO/Pd films electrodes were tested by cyclic voltammetry, impedance and constant charge/discharge measurements. The results show that the films electrodes have excellent electrochemical properties. When the current density were 0.5A/g, 1.0A/g, 2.0A/g, 3.0A/g, the specific capacitance of NiAl-MMO films electrodes arrived at 533, 500, 467, 450 F/g. The EIS results show that the internal resistance and transfer resistance of NiAl-MMO films electrodes were 3.1 ? and 0.8 ?. For different proportion of NiCoAl-MMO testing, the Ni CoAl- MMO(1.5:1.5:1) films electrodes occupied the maximum capacitance value. When the current density arrived at 0.5A/g, 0.8A/g, 1.0A/g, 2.0A/g, the capacitance value is 1167F/g, 1066F/g, 933F/g, 866 F/g. The EIS results show that the internal resistance and transfer resistance of NiCoAl-MMO films electrodes were 1.6 ? and 0.8 ?. When the current density were 0.5A/g, 1.0A/g, 2.0A/g, 3.0A/g, the specific capacitance of NiAl-MMO/Pd films electrodes arrived at 667F/g, 600F/g, 567F/g, 600 F/g, The EIS results show that the internal resistance and transfer resistance of NiAl-MMO/Pd films electrodes were 1.5 ? and 0.8 ?.The desalination performance of NiAl-MMO, NiCoAl-MMO and NiAl-MMO/Pd films electrodes were tested. The results showed that the highest desalination efficiency and the adsorption capacity of NiAl-MMO films electrodes could up to 58.17% and 0.51mg/cm2, when the initial concentration of NaCl solution was 0.003mol/L, the voltage was 1.0 V and the pH value arrived to 8. The NiAl-MMO films electrodes could be regenerated by electrodes reverse. The stripping rate could reach 87.96%. Under the same experimental conditions, The desalination efficiency of NiCoAl-MMO films electrodes was up to 61.01%. The NiCoAl-MMO films electrodes could be regenerated with desorption rate of 86.78% by electrodes reversion. After ten times electric adsorption cycle, the adsorption rate has no obvious decrease. The results reflected the excellent repeated performance of NiCoAl-MMO films electrodes. Furthermore, the adsorption kinetics and thermodynamics of the NiCoAl-MMO films electrodes were discussed. The results showed that NiCoAl-MMO materials attributes to secondary dynamic suggesting that the adsorption process might be chemical adsorption. A pseudo first order kinetics equation could be described the Cl- electrosorption kinetic data well, suggesting that the electrosorption of Cl- attributes to monolayer adsorption. Langmuir model gave a better fit to the adsorption isotherm equilibrium data. The electrosorption and reduction experiments were studied about NiAl-MMO/Pd for nitrate. The results showed that the highest desalination efficiency of NiAl-MMO films electrodes could up to 40.32%, when the initial concentration of NaNO3 solution was 0.003 mol/L, the voltage was 1.0 V and the pH value arrived to 8. The NiAl-MMO films electrodes could be regenerated with a desorption rate of 88.43% by electrodes reversion. Moreover, the NiAl-MMO become to NiAl-MMO/Pd with adding palladium to NiAl-MMO. The nitrate reduction experiments results for NiAl-MMO/Pd showed the reduction effect arrived to best with 3% of Pd load. The process produced intermediate nitrite and the byproduct of ammonia nitrogen at the same time.