Polypyrrole/bacterial cellulose nanofiber composites for hexavalent chromium removal

Polypyrrole/bacterial cellulose (PPy/BC) composites with nanofiber structure were prepared by a facile in situ oxidative polymerization for the efficient removal of hexavalent chromium (Cr(VI)) from aqueous solution. The characteristics of the adsorbent were analysed by SEM, TEM, BET, EDX, FT-IR, and XPS and PPy found to be evenly wrapped on cellulose surfaces to form a core-shell structure and the specific surface area calculated at 95.9 m(2) g(-1). Benefiting from high surface area, PPy/BC efficiently removed Cr(VI) and possessed a maximum adsorption capacity of 555.6 mg g(-1) at 298 K and pH 2. Adsorption data was determined to conform to the Langmuir isotherm model and pseudo-second-order model. Cr(VI) adsorption on PPy/BC was involved in ion exchange and electrostatic attractions. Meanwhile, a portion of Cr(VI) was reduced to trivalent chromium (Cr(III)) by pyrrolic nitrogen and then retained on PPy/BC surfaces by chelation. In addition, PPy/BC maintained 70.5% of its initial adsorption capacity after five adsorption and desorption cycles. This study demonstrated that PPy/BC can be a cost-effective, reusable, and highly efficient adsorbent for Cr(VI) removal.

Automated summary

PPy/BC composites with nanofiber structure were prepared for efficient removal of Cr(VI) from aqueous solution. The adsorbent exhibited high specific surface area, maximum adsorption capacity, and maintained stability after multiple cycles. The adsorption mechanism involved ion exchange, electrostatic attractions, and chelation of Cr(VI) onto PPy/BC surfaces.