title: Bilirubin oxidase based enzymatic air-breathing cathode: Operation under pristine and contaminated conditions.
abstract: The performance of bilirubin oxidase (BOx) based air breathing cathode was constantly monitored over 45 days. The effect of electrolyte composition on the cathode oxygen reduction reaction (ORR) output was investigated. Particularly, deactivation of the electrocatalytic activity of the enzyme in phosphate buffer saline (PBS) solution and in activated sludge (AS) was evaluated. The greatest drop in current density was observed during the first 3 days of constant operation with a decrease of ~60 μA cm(-2) day(-1). The rate of decrease slowed to ~10 μA cm(-2) day(-1) (day 3 to 9) and then to ~1.5 μA cm(-2)day(-1) thereafter (day 9 to 45). Despite the constant decrease in output, the BOx cathode generated residual current after 45 days operations with an open circuit potential (OCP) of 475 mV vs. Ag/AgCl. Enzyme deactivation was also studied in AS to simulate an environment close to the real waste operation with pollutants, solid particles and bacteria. The presence of low-molecular weight soluble contaminants was identified as the main reason for an immediate enzymatic deactivation within few hours of cathode operation. The presence of solid particles and bacteria does not affect the natural degradation of the enzyme.
authors.affiliation: Department of Chemical & Biological Engineering, Center for Micro-Engineered Materials (CMEM), University of New Mexico, Albuquerque, NM 87131, USA; Department of Civil Engineering, Center for Emerging Energy Technologies (CEET), University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Carlo
authors.initials: C
authors.lastname: Santoro
authors.affiliation: Department of Chemical & Biological Engineering, Center for Micro-Engineered Materials (CMEM), University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Sofia
authors.initials: S
authors.lastname: Babanova
authors.affiliation: Laboratoire de Génie Chimique, CNRS, Université de Toulouse, 4 allée Emile Monso, 31029 Toulouse, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Erable
authors.affiliation: Department of Civil Engineering, Center for Emerging Energy Technologies (CEET), University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Schuler
authors.affiliation: Department of Chemical & Biological Engineering, Center for Micro-Engineered Materials (CMEM), University of New Mexico, Albuquerque, NM 87131, USA. Electronic address: plamen@unm.edu.
authors.forename: Plamen
authors.initials: P
authors.lastname: Atanassov
mesh_terms: D000388:Air; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D002021:Buffers; D004553:Electric Conductivity; D004563:Electrochemistry; D004566:Electrodes; D004785:Environmental Pollutants / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006999:Hypocreales / Q000201:enzymology; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D012722:Sewage / Q000382:microbiology
chemical_list: D002021:Buffers; D004785:Environmental Pollutants; D004800:Enzymes, Immobilized; D012722:Sewage; D044925:Oxidoreductases Acting on CH-CH Group Donors; C042401:bilirubin oxidase; D010100:Oxygen
keywords: Bilirubin oxidase; Enzymes durability; Oxygen reduction reaction; PBS conditions; Pollutants