Preparation of polypyrrole/chitosan/carbon nanotube composite nano-electrode and application to capacitive deionization process for removing Cu2+

Capacity deionization technology, an innovative desalination technology, is applied to removing heavy metal ions. As a new pseudo-capacitance electrode material, polypyrrole (PPy) is considered as a promising and perfect electrode material of CDI. In this paper, polypyrrole/chitosan/carbon nanotubes (PPy/CS/CNT) composite nano-electrode were prepared by in situ polymerization, and its surface characteristics, electrochemical properties and adsorption performances were tested. SEM and TEM images shown that CS and PPy are coated on CNT surface in order. The BET surface area and BJH pore diameter of PPy/CS/CNT composite nanoelectrode are 33.51 m2/g and 34.57 nm, respecitively, tested by nitrogen adsorption-desorption isotherms. Cyclic voltammetry (CV) test shown that specific capacitance value and adsorption capacity of the PPy/CS/CNT composite nanoelectrode both are increased first and then decreased with the increasing of the CS dosages, and the highest values are 103.19 F/g and 16.83 mg/g at mass ratio of CS:Py = 2:10, which are 1.6 times and 2.1 times of that of PPy/CNT composite nanoelectrode, respectively. The adsorption kinetic data followed the pseudo-second-order kinetic model, indicating a chemical adsorption process of composite electrode for heavy metal ions.