Oxygen reduction at microelectrodes : application to the dissolved oxygen sensor for in situ oceanographic measurements
Oxygen reduction at microelectrodes : application to the dissolved oxygen sensor for in situ oceanographic measurements
This work describes the development of an accurate and reliable electrochemical dissolved oxygen sensor for oceanographic measurements. The amperometric response of the sensor gives direct information on the concentration of dissolved oxygen, which is reduced at a microdisc cathode to peroxide species and water. A number of parameters including electrode material, potential waveform, the apparent number of electrons (napp) as well as temperature, salinity and flow effects, are investigated.
Parameters for platinum microcathodes electrochemical cleaning are reported, which yield very stable amperometric response under continuous operation, with a maximum standard deviation of the limiting current under 1.5%. An automated calibration method developed to accurately characterise the electrodes is described. Excellent linearity is obtained for electrodes tested and in each case napp is extracted. As an alternative to calibration, an analytical treatment which accounts for temperature and salinity effects is given to calculate the dissolved oxygen concentration directly from the limiting current.
A prototype oceanographic dissolved oxygen sensor which includes flow control arrangement is described. Its performance in field trials carried out during the RRS Discovery transatlantic cruise D279 is presented. The results of eight deep sea deployments are compared with the dissolved oxygen – depth profiles obtained by onboard Winkler titration of the samples bottled at discrete depths.
Two approaches alternative to the limiting current measurements are also reported, with the aim to perform the measurements directly in the water column on a moving probe: the vibration of the microelectrode to create controlled forced convection and transient measurements with the potential step durations down to 1 ms. The latter is shown to be capable of quantitative determination of oxygen, while showing high immunity to the external flow.
University of Southampton
Sosna, Maciej
bb06b52f-f70a-490e-a296-e3768f31cbfe
2006
Sosna, Maciej
bb06b52f-f70a-490e-a296-e3768f31cbfe
Sosna, Maciej
(2006)
Oxygen reduction at microelectrodes : application to the dissolved oxygen sensor for in situ oceanographic measurements.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This work describes the development of an accurate and reliable electrochemical dissolved oxygen sensor for oceanographic measurements. The amperometric response of the sensor gives direct information on the concentration of dissolved oxygen, which is reduced at a microdisc cathode to peroxide species and water. A number of parameters including electrode material, potential waveform, the apparent number of electrons (napp) as well as temperature, salinity and flow effects, are investigated.
Parameters for platinum microcathodes electrochemical cleaning are reported, which yield very stable amperometric response under continuous operation, with a maximum standard deviation of the limiting current under 1.5%. An automated calibration method developed to accurately characterise the electrodes is described. Excellent linearity is obtained for electrodes tested and in each case napp is extracted. As an alternative to calibration, an analytical treatment which accounts for temperature and salinity effects is given to calculate the dissolved oxygen concentration directly from the limiting current.
A prototype oceanographic dissolved oxygen sensor which includes flow control arrangement is described. Its performance in field trials carried out during the RRS Discovery transatlantic cruise D279 is presented. The results of eight deep sea deployments are compared with the dissolved oxygen – depth profiles obtained by onboard Winkler titration of the samples bottled at discrete depths.
Two approaches alternative to the limiting current measurements are also reported, with the aim to perform the measurements directly in the water column on a moving probe: the vibration of the microelectrode to create controlled forced convection and transient measurements with the potential step durations down to 1 ms. The latter is shown to be capable of quantitative determination of oxygen, while showing high immunity to the external flow.
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Published date: 2006
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Local EPrints ID: 466116
URI: http://eprints.soton.ac.uk/id/eprint/466116
PURE UUID: 7fbbc420-2a9b-4c44-9a29-3ccc27805f0a
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Date deposited: 05 Jul 2022 04:23
Last modified: 16 Mar 2024 20:31
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Author:
Maciej Sosna
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