Evaluation of a visible light-responsive polyaniline nanofiber˗cadmium sulfide quantum dots photocathode for simultaneous hexavalent chromium reduction and electricity generation in photo-microbial fuel cell

Abstract

Photo˗microbial fuel cells (Photo˗MFCs) technology have been utilized for cathodic reduction of hexavalent chromium (Cr(VI)) in wastewater and simultaneously electricity generation by using a photocathode. In the present manuscript, polyaniline nanofiber (PANI)˗CdS Quantum Dots (QDs) photocathode is prepared via an in˗situ method to investigate its performance for reduction of Cr(VI) from wastewaters in Photo˗MFC. The structural and optical analyses confirm the enhanced construction and photocatalytic properties of the nanocomposite with high absorption in the visible range. The selected photocathode is also characterized by photo˗electrochemical techniques to determine its sensitivity to visible light. In the photoreduction process, the Photo˗MFC system equipped with the PANI˗CdS QDs photocathode has acquired an outstanding reduction ratio up to 97.4% at a pH value of 2, an initial concentration of 10 mg/L, within illumination time of 8 h and these results follow a pseudo-second˗order kinetics with a constant of 0.081 mgL ˗1 h ˗1 , as well. Meanwhile, the Photo˗MFC achieves the highest maximum power density of 166.93 mW.m −2 in the presence of visible light. The present study has successfully confirmed that, Photo˗MFC equipped with a PANI˗CdS QDs photocathode, can be a promising technology for the reduction of Cr(VI) with an enhanced output power generation simultaneously. • Polyaniline-CdS Quantum Dots photocathode is prepared via an in-situ method. • Photocathode is utilized for the reduction of Cr(VI) in a Photo-MFC. • Simultaneous electricity generation is evaluated in the Photo-MFC. • Photo-MFC equipped with PANI-CdS QDs achieves the reduction efficiency up 97.4%. • Photo-MFC achieves the highest power density with the visible light illumination.