Effect of conductive polyaniline on the cationic and anionic dye adsorption properties of amphoteric alginate/chitosan composite foams

Doped polyaniline is a widely used conductive material and could be used for adsorption based on the electrostatic neutralization effect through the protonation of the imine group. However, the adsorption effect and mechanism towards cationic and anionic pollutants are not clear. Herein, the conductive sulfonic acid doped polyaniline was introduced into alginate/chitosan amphoteric composite foams prepared with a thermal induced phase separation technique. The composite foams were characterized in terms of scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electrochemical impedance. The composite foam exhibited rich pores and fibrous matrix due to the unique ternary solvent system. The polyaniline was well-distributed and enhanced the cationic dye adsorption ability, contrary to that of anionic dye. Compared with pure alginate/chitosan composite foam, the adsorption capacity of methylene blue was increased by 91.1%, and that of acid blue-113 was reduced by 49.2%. The adsorption rate of the two dyes was both increased. Polyaniline addition enhances the ionic mobility rate and accelerates the movement of dye molecules. Moreover, the composite foams exhibited excellent selective adsorption capacity and reusability. The study indicates that the conductive polymer could find its share in developing high-performance adsorbents.