Electrodeposited MnO2-based Capacitive Composite Electrodes for Pb2+ Adsorption

In order to effectively realize the removal of low concentrations of lead ions in wastewater via capacitive deionization technology, MnO2 composite electrodes were prepared by a galvanostatic co-deposition approach, where polyaniline (PANI) and graphene were added to an MnO2 deposition solution and nickel foam was chosen as the substrate of the electrode. The microstructure, capacitance characteristics and adsorption behavior of Pb2+ ions of the electrodes were analyzed by scanning electron microscopy, X-ray diffraction, X ray photoelectron spectroscopy, laser Raman spectroscopy, cyclic voltammetry and capacitance deionization processes. The experimental results showed that the MnO2-PANI-graphene composite electrode has a high specific capacitance (132.8 F/g) and a 61.8% removal rate for simulated wastewater containing 20 mg/L Pb2 + ions under the conditions of 30�C and 1 mA/cm2, with the addition of 1 g/L PANI and 3 g/L graphene, respectively. Electroadsorption process was in accordance with the Lagergren quasi-second-order kinetic equation. The co-deposition of PANI and graphene oxide could play obvious role in enhancing the adsorption capacity and stability of the electrodes.