Synergistic interaction of biocatalyst with bio-anode as a function of electrode materials S. Srikanth, T. Pavani, P.N. Sarma, S. Venkata Mohan* Bioengineering and Environmental Centre, Indian Institute of Chemical Technology, Hyderabad 500 607, India article info Article history: Received 15 September 2010 Received in revised form 25 October 2010 Accepted 9 November 2010 Available online 18 December 2010 Keywords: Bio-electrochemical system (BES) Microbial fuel cell (MFC) Anode respiring bacteria (ARB) Bioelectricity Microbial electrolysis cell (MEC) Voltammetry abstract Comprehensive study was performed to understand the synergistic interaction between the biocatalyst and anode in terms of electron discharge (ED) pattern and microbial growth by varying electrode (bio-anode) materials viz., graphite, aluminum, brass, copper, nickel and stainless steel. Experiments were performed in bio-electrochemical cell consisting of three electrodes (bio-anode as working electrode, carbon rod as counter electrode and Ag/AgCl(S) as reference electrode) employing anaerobic mixed culture as anodic biocatalyst. Voltam- metric and chronoamperometric analysis were used to enumerate the ED and redox reac- tions. Presence of higher microbial population and dominance of Gram positive bacteria with higher ED supported graphite function as a good bio-anode material. Nickel and stainless steel showed higher ED after graphite associated with dominance of Gram positive bacterial population. Although higher ED was noticed with brass, metal oxidation and decrement in ED with time doesn’t support its function as bio-anode. In spite of higher ED than nickel and stainless steel, aluminum and copper showed significant metal oxidation leading to change in both physical and electrochemical properties along with dominant growth of Gram negative bacteria. This study gives a comprehensive idea on biocatalyst interaction with anode in extracellular electron transfer which is important in improving the anode perfor- mance. Juxtaposing the results, it can be deduced that the outcome of the present study can be extended to all bio-electrochemical systems including microbial fuel cell (MFC). ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. 1. Introduction Protons (H þ ) and electrons (e  ) are generated through a series of bio-electrochemical redox reactions during substrate degradation by micro-organisms. These protons and electrons are responsible for the development of potential difference between anode and cathode resulting in electron flow (current) [1e5]. Bio-electrochemical systems like microbial fuel cell (MFC) facilitates the direct conversion of chemical energy of the substrate to useful energy through the action of micro-organisms adhering to the anode surface. The concept of MFC has already been well established in the direction of utilizing wastewater as anodic fuel [3,4,6e16]. Utilization of wastewater as anodic fuel for electricity generation through the action of biocatalyst makes MFC as a sustainable tech- nology for energy generation as well as waste management [3,4,6e16]. However, there still remain certain limitations to overcome for these technologies to become an alternative for traditional energy production processes. In these systems, activity of anode respiring bacteria (ARB) is essential to liberate electrons from the oxidation of organic matter. Anode chamber plays a crucial role where the reactions take place * Corresponding author. Tel.: þ91 40 27191664. E-mail address: vmohan_s@yahoo.com (S. Venkata Mohan). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 36 (2011) 2271 e2280 0360-3199/$ e see front matter ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.11.031