Conductive microbial cellulose as a novel biocathode for Cr (VI) bioreduction.

In the present study, microbial cellulose (MC) as a carbohydrate polymer was made conductive by oxidative polymerization with aniline. Sulfate-reducing bacteria (SRB) were immobilized on the surface of the conductive biopolymer, and this was used as a biocathode in a bioreduction process to reduce Cr (VI) as a model of heavy metals. The results of Fourier transform infrared analysis confirmed that the polyaniline was distributed on the cellulose surface. The maximum tensile stress of the conductive biopolymer was obtained 23MPa using calculating Young's modulus. A current density of 60mA/m2 was determined as optimal, and an increase in pH from 5 to 7 significantly reduced the required time for reduction of Cr (VI). The system reached >99% removal of Cr (VI) within 1.5h at pH 7. Kinetic experiment studies showed a high constant rate (mean Kobs 0.78, R2 0.95). The results showed that the conductive MC can be used as an appropriate bioelectrode to reduce Cr (VI) in bioelectrochemical processes. It is expected that experimental results could be used as a reference for the utilization of MC in bioelectrochemical systems.