Polypyrrole–polyaniline-water hyacinth leaf protein concentrate composite for the removal of Cr(VI) from aqueous solution: kinetics, isotherm and thermodynamic studies

Abstract

ABSTRACT. This work focused on the extraction of “water hyacinth leaf protein concentrate” (WHLPC) and preparation of polypyrrole (PPy), polyaniline (PANI) and polypyrrole-polyaniline copolymer (PPy/PANI) coated WHLPC by in situ polymerization and investigate their application for the removal of Cr(VI) from aqueous solution. After optimizing the experimental conditions like pH, adsorbent dosage, contact time and initial concentration it was found that the kinetics and isotherm data were well fitted to the pseudo-second-order and Langmuir models, respectively. PPy/PANI/WHLPC was found to be an efficient material compared to the other polymer-coated adsorbents with maximum adsorption capacity of 230 mg/g. The presence of counter ions ((NO3-, Cl-, HPO42-, SO42+ and HCO3- ions) slightly decreases the Cr(VI) removal efficiency PPy/PANI/WHLPC. The thermodynamic study reveals that the adsorption of Cr(VI) onto PPY/PANI/WHLPC is endothermic, thermodynamically feasible, and spontaneous. In addition, reusability of the material indicated high removal efficiency for two adsorption cycles.   KEY WORDS: Polypyrrole, Polyaniline, Protein concentrate, Water hyacinth, Chromium Bull. Chem. Soc. Ethiop. 2022, 36(3), 571-584.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i3.7