Enhanced desalination performances by using porous polyaniline-activated carbon composite flow-electrodes in capacitive deionization system

Abstract

Flow electrodes capacitive deionization (FCDI) is a promising CDI variant, and has been used in various fields like brackishwater desalination and nutrients recovery. Activated carbon (AC), a prevalent FCDI electrode, suffers from low ion adsorption capacity, poor electric conductivity, and large viscosity, which restrict their large-scale applications. In this study, situ polymerization was utilized to prepare porous polyaniline and activated carbon composite (pPANI-AC) electrode with the assistance of ice template. This innovative electrode took advantages of the pseudocapacitive effects of porous polyaniline and the ion channels was increased by exposing the pores and surface of the porous activated carbon. The new composite electrode has an increase in specific surface area from 213.5 m2 g−1 to 616.1 m2 g−1, and an increase in capacitance from 93 to 178 F g−1, and the viscosity flow electrodes decreases from 127 to 21 Pas. Reduced viscosity and intrinsic impedance of the flow electrode result in an increase in flow electrode conductivity and ionic capacity of the FCDI system that has a 70 % increase in desalination capacity. This study developed a low-cost and environmentally friendly active material for high-efficient flowable electrodes, which will pave way for the real applications of FCDI technology.