Free-Standing Bacterial Cellulose/Polypyrrole Composites for Eco-Friendly Remediation of Hexavalent Chromium Ions

Abstract

Drinking water quality requirements are getting stricter but water sources are limited. Therefore, effective ways to purify it must be developed. In order to remove toxic Cr(VI) from wastewater, efficient, nontoxic, sustainable, resilient biocomposites based on bacterial cellulose (BC) and polypyrrole (PPy) have been fabricated. The free-standing BC/PPy composites, allowing easy handling during and after water treatment, were successfully prepared by the oxidative polymerization of pyrrole on the BC surface. The variation in the physical state of BC sheets used for coating by PPy was done to study the rheological properties and Cr(VI) removal capacity. Characterization techniques like FTIR, SEM, BET, thermogravimetric analysis, and rheological analyses established the morphology and structural properties of the prepared biocomposites. The physical state of the bacterial cellulose used for the coating by PPy positively affected the mechanical and thermal stabilities of the resulting BC/PPy composites but had almost no effect on the removal capacity of hexavalent chromium. The free-standing BC/PPy composites reached a specific surface area of 61.96 m2 g–1 and a pore volume of 0.097 cm3 g–1, showing more than a threefold increase compared to neat BC sheets. The coating of BC by PPy markedly improved the maximum adsorption capacity of Cr(VI). The experimental Cr(VI) adsorption data fitted using Langmuir’s isotherm model indicated homogeneous monolayer adsorption of Cr(VI) ions onto the BC/PPy surface. The Cr(VI) maximum adsorption capacity of BC/PPy composites was determined to be 294.1 mg g–1. Furthermore, the BC/PPy composites were proved to be excellent catalysts for the photocatalytic reduction of toxic Cr(VI) into nontoxic Cr(III) ions. These results suggest that the free-standing BC/PPy composites could be used as alternative materials for eco-friendly remediation of hexavalent chromium ions from wastewater.Drinking water quality requirements are getting stricter but water sources are limited. Therefore, effective ways to purify it must be developed. In order to remove toxic Cr(VI) from wastewater, efficient, nontoxic, sustainable, resilient biocomposites based on bacterial cellulose (BC) and polypyrrole (PPy) have been fabricated. The free-standing BC/PPy composites, allowing easy handling during and after water treatment, were successfully prepared by the oxidative polymerization of pyrrole on the BC surface. The variation in the physical state of BC sheets used for coating by PPy was done to study the rheological properties and Cr(VI) removal capacity. Characterization techniques like FTIR, SEM, BET, thermogravimetric analysis, and rheological analyses established the morphology and structural properties of the prepared biocomposites. The physical state of the bacterial cellulose used for the coating by PPy positively affected the mechanical and thermal stabilities of the resulting BC/PPy composites but had almost no effect on the removal capacity of hexavalent chromium. The free-standing BC/PPy composites reached a specific surface area of 61.96 m2 g–1 and a pore volume of 0.097 cm3 g–1, showing more than a threefold increase compared to neat BC sheets. The coating of BC by PPy markedly improved the maximum adsorption capacity of Cr(VI). The experimental Cr(VI) adsorption data fitted using Langmuir’s isotherm model indicated homogeneous monolayer adsorption of Cr(VI) ions onto the BC/PPy surface. The Cr(VI) maximum adsorption capacity of BC/PPy composites was determined to be 294.1 mg g–1. Furthermore, the BC/PPy composites were proved to be excellent catalysts for the photocatalytic reduction of toxic Cr(VI) into nontoxic Cr(III) ions. These results suggest that the free-standing BC/PPy composites could be used as alternative materials for eco-friendly remediation of hexavalent chromium ions from wastewater.