Feasibility Study of Azo Dye Treatment by Decolorized Metabolites-Assisted Salt-Bearing Microbial Fuel Cells

Abstract

Prior findings mentioned that -OH and -NH2 substitute-containing auxochrome compounds (e.g., 2-aminophenol and 1,2-dihydroxybenzene) could act as electron shuttles (ESs) for simultaneous dye decolorization and bioelectricity generation (DD&BG) in microbial fuel cells (MFCs). This feasibility study used decolorized intermediates (DIs) of reactive blue 171, reactive blue 5, reactive red 198 to show such significant electron-shuttling capabilities. Cyclic voltammetric inspections clearly revealed that some of DIs could act as ESs to enhance dye-decolorizing and bioelectricity-generating capabilities without dispute. However, electron transfer (ET) efficiency significantly reduced ca. 40% at higher salt conditions. With supplementation of DIs, ET efficiency was apparently augmented for highly efficient DD and BG. Meanwhile, significant stimulation of ET characteristics also overcame osmotic pressure-gradients between intracellular and extracellular compartments for promising DD and BG. Accumulation of DIs was kinetically favorable for expression of dye-decolorizing capabilities. Of course, such accumulation of DIs autocatalytically enhanced DD and MFC-assisted treatment was technically appropriate for ET-based bioremediation.