Nanoconducting polymer: an effective adsorbent for dyes

Abstract

The nanostructured sulfonated polypyrrole adsorbents have been prepared by copolymerization of pyrrole and sulfophenylenediamine to study the adsorption efficiency of the polymer-based nano-adsorbents for the adsorption of anionic and cationic dyes in aqueous solution. The present study reveals that the incorporation of sulfophenylenediamine (SPDA) with pyrrole (Py) monomer extremely improved the adsorption efficiency of the prepared poly(pyrrole-co-sulfophenylenediamine) adsorbents for the anionic Congo red and the cationic methylene blue dyes in aqueous solution. This high adsorption efficiency of the polymer-based (PPY–SPDA) adsorbents toward the anionic and cationic dyes in aqueous solution may emerge from the higher number of functional groups such as NH/NH2/SO3H present in the copolymers. The effects of temperature, pH, the concentration of dyes, contact time and the dosage of adsorbents have been studied in the batch adsorption process. The fine nanoparticles of PPY–SPDA prepared from 1:0.5 mol ratio exhibited a complete removal of both the anionic and cationic dyes from the aqueous solution. For Congo Red dye, 100% adsorption efficiency was exhibited at the optimum condition of the adsorption using an adsorbent dosage of 0.15 g (PPY–SPDA copolymer) at pH 1 with a contact time of 3 h, while for methylene blue dye, the optimum condition of the adsorption was found using an adsorbent dosage of 0.35 g (PPY–SPDA copolymer) at pH 11 with at a contact time of 2.5 h. The polymer-based nano-adsorbents were characterized by FTIR for its functional groups present in the polymer, FESEM for its morphology and BET for its surface area. The adsorption data matched better to the Freundlich isotherm model than the Langmuir isotherm model, and the kinetic data were found to follow the pseudo-second-order model.