Exposure of Geobacter-enriched electro-active biofilm to [BMIM][NTf2] ionic liquid inhibits current generation in a bioelectrochemical system.

In this work, the effect of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) ionic liquid (IL) on the behavior of bioelectrochemical systems (BES) was studied in operando. Geobacter-enriched (>60%) biofilms were formed on the anodes (+0.2 V vs. Ag/AgCl potential) and their response to adding [BMIM][NTf2] in 0, 0.22, 0.44 and 0.65 mM concentrations to the BES anolytes was evaluated with acetate substrate. The average peak current densities (7.32; 5.52; 4.24; 2.04 A m-2, respectively) showed decreasing values with increasing IL concentration. By replacing the anolytes after each substrate feeding cycle, the time-dependency of the impact caused by the ionic liquid could be monitored. Performing non-turnover cyclic voltammetry on the anodic biofilms, it could be concluded that the loss of their electrochemical activity was associated with the increasing concentration of [BMIM][NTf2]. Persisting physical interactions taking place between the ionic liquid and the cells/cell membrane proteins (e.g. cytochromes) were considered and elaborated concerning the underlying limitation mechanism.