title: Temperature dependence and interferences of NO and N₂O microelectrodes used in wastewater treatment.
abstract: Electrodes for nitric and nitrous oxide have been on the market for some time, but have not yet been tested for an application in wastewater treatment processes. Both sensors were therefore assessed with respect to their (non)linear response, temperature dependence and potential cross sensitivity to dissolved compounds, which are present and highly dynamic in nitrogen conversion processes (nitric oxide, nitrous oxide, nitrogen dioxide, ammonia, hydrazine, hydroxylamine, nitrous acid, oxygen, and carbon dioxide). Off-gas measurements were employed to differentiate between cross sensitivity to interfering components and chemical nitric oxide or nitrous oxide production. Significant cross sensitivities were detected for both sensors: by the nitrous oxide sensor to nitric oxide and by the nitric oxide sensor to ammonia, hydrazine, hydroxylamine and nitrous acid. These interferences could, however, be removed by correction functions. Temperature fluctuations in the range of ±1 °C lead to artifacts of ±3.5% for the nitric oxide and ±3.9% for the nitrous oxide sensor and can be corrected with exponential equations. The results from this study help to significantly shorten and optimize the determination of the correction functions and are therefore relevant for all users of nitric and nitrous oxide electrodes.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
authors.forename: Sarina
authors.initials: S
authors.lastname: Jenni
authors.forename: Joachim
authors.initials: J
authors.lastname: Mohn
authors.forename: Lukas
authors.initials: L
authors.lastname: Emmenegger
authors.forename: Kai M
authors.initials: KM
authors.lastname: Udert
mesh_terms: D008839:Microelectrodes; D009569:Nitric Oxide / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000737:chemistry*; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000295:instrumentation*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D014874:Water Pollutants, Chemical; D009569:Nitric Oxide; D009584:Nitrogen; D009585:Nitrogen Dioxide