Adsorption and subsequent detoxification of hexavalent chromium in aqueous solution using polypyrrole-bacterial extracellular polysaccharide nanocomposite

The aim of this study was to assess the adsorption and Cr(VI) detoxification potential of polypyrrole-bacterial extracellular polysaccharide (PPy-EPS) nanocomposite. The nanocomposite was synthesized by in situ chemical oxidative polymerization of pyrrole monomer with bacterial extracellular polysaccharide (EPS). Scanning and transmission electron micrographs showed the nanocomposites to be irregular in shape and mostly present in aggregates. Fourier transform infrared analyses illustrate the characteristic peaks (2934, 1548, 1463, and 1165 cm⁻¹) of both pyrrole and bacterial extracellular polysaccharides. X-ray diffractogram showed the amorphous nature of the nanocomposite, and the surface area of the PPy-EPS nanocomposite was measured as 26.21 m² g⁻¹. The nanocomposite efficiently reduced more than 80% of Cr(VI) within 30 min. The X-ray diffractogram corresponding to the crystal planes ((012), (110)) of Cr₂O₃ further confirmed the reduction of Cr(VI). The results of the study confirm PPy-EPS nanocomposite as suitable option for the treatment of Cr(VI)-bearing industrial wastewaters.