Kinetics of biocathodic electron transfer in a bioelectrochemical system coupled with chemical absorption for NO removal.

A microbial electrolysis cell (MEC) has been developing for enhanced absorbent regeneration in a chemical absorption-biological reduction integrated process for NO removal. In this work, the kinetics of electron transfer involved in the biocathodes along Fe(III)EDTA and Fe(II)EDTA-NO reduction was analyzed simultaneously. A modified Nernst-Monod kinetics considering the Faraday efficiency was applied to describe the electron transfer kinetics of Fe(III)EDTA reduction. The effects of substrate concentration, biocathodic potential on current density predicted by the model have been validated by the experimental results. Furthermore, extended from the kinetics of Fe(III)EDTA reduction, the electron transfer kinetics of Fe(II)EDTA-NO reduction was developed with a semi-experimental method, while both direct electrochemical and bioelectrochemical processes were taken into consideration at the same time. It was revealed that the developed model could simulate the electron transfer kinetics well. This work could not only help advance the biocathodic reduction ability and the utilization efficiency of electric power, but also provide insights into the industrial scale-up and application of the system.