The Effect of Plasma Treatment of Electrodes on the Development of Electrochemically Active Biofilms

VICTORIA FLEXER; MARQUE, M.; DONOSE, B.C.; VIRDIS, B.; KELLER, J.

Santiago de Querétaro

Conferencia; 64th Annual Meeting of the International Society of Electrochemistry; 2013

International Society of Electrochemistry

In microbial bioelectrochemical systems, whole cells are used as biocatalysts to catalyse oxidation and reduction reactions. Microbial fuel cells are the classical and more widely studied example of bioelectrochemical systems, performing the double task of wastewater treatment and electricity generation. More recently, the concept has been extended to the possibility of generating higher value products than electricity. In a typical microbial system, the anode is used to harvest electrons from wastewater, while oxidising organic pollutants, with the electrons being used as reducing power in the cathode to create valuable products. The viability of prospective applications of microbial bioelectrochemical systems is highly dependent on performance improvement, i.e. in current increase. Current production is dependent, among other factors, on the microbial consortia, bioelectrochemical reactor design, and electrode materials. One strategy to improve bacteria-electrode interaction and therefore performance in terms of current, is to apply some type of pre-treatment to the electrodes before exposing them to biofilm development. Although some pre-activation techniques proposed in the past have shown improvements in performance, they employ dangerous chemicals or extreme conditions, and sometimes even long, cumbersome, and multistep techniques. We will present results on a new pre-activation technique for carbonaceous electrode materials. Plasma treatment can be used to modify a wide variety of material surfaces in a nonspecific manner by changing the wettability, or in a more specific manner by introducing a variety of functional groups depending on the processing gas. We aim at changing the inherited hydrophobicity of carbonaceous materials, in order to increase microorganisms adhesion. Here we present results that show that plasma cleaning is a straightforward, simple, cheap and safe technique for the pre-activation of electrode materials to be used in bioelectrochemical systems. Our results show that initial bacterial adhesion is considerable accelerated when electrodes were pre-treated with either O2 or N2 plasma before being introduced in a bioelectrochemical reactor. The enhanced bacterial adhesion leads to a much faster bioelectrocatalytic signal development when compared to non-treated electrodes. The current development profiles and bacterial growth rate were compared for the different electrodes. The new technique was tested for both microbial anodes and cathodes inoculated with mixed culture inocula. The technique showed improved current production in a wide variety of materials, including smooth glassy carbon, rough graphite felt and also in new purposely designs for BES three-dimensional materials.