Enhanced electrosorption capacity for lead ion removal with polypyrrole and air-plasma activated carbon nanotube composite electrode

ABSTRACT Polypyrrole (PPy) and air‐plasma activated carbon nanotube (CNT) composites (P‐CNT‐PPy) prepared via in situ chemical oxidative polymerization are studied to improve the electrosorption capacity of CNT‐based electrodes for the removal of lead ions. For comparison, the PPy prepared on the CNTs without plasma activation is labeled as CNT/PPy. The morphology of the composite was observed by scanning electron microscopy (SEM), and pore structures were studied by N2 adsorption‐desorption isotherms. The electrochemical capacitance properties of the composite were measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge‐discharge in lead solutions. With plasma‐activation, the specific surface area of the P‐CNT‐PPy composite is larger than that of CNT/PPy. Additionally, the P‐CNT‐PPy composites exhibit excellent electrochemical performance in lead solution, with a higher specific capacitance and smaller charge transfer resistance than that of CNT/PPy. XPS elemental analysis and electrosorption and regeneration results show that the electrosorption and desorption process is reversible under a voltage of 450 mV. The electrosorption kinetics of P‐CNT‐PPy electrodes abide by pseudo‐second‐order model reaction. The lead ion electrosorption experiments agree with the Langmuir model, and the equilibrium electrosorption capacity of the P‐CNT‐PPy electrodes is 3.6 and 1.3 times higher than that of the CNT and CNT/PPy, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41793.