Oxygen measurement via phosphorescence: reaction of sodium dithionite with dissolved oxygen

Zhimin Tao; Jerry Goodisman; Abdul Kader Souid

doi:10.1021/jp710176z

Oxygen measurement via phosphorescence: reaction of sodium dithionite with dissolved oxygen

Zhimin Tao, Jerry Goodisman, Abdul Kader Souid

Research output: Contribution to journal › Article › peer-review

31 Citations (Scopus)

Abstract

A homemade instrument for the measurement of oxygen concentration in aqueous solutions measures the decay rate of the phosphorescence of a Pd-porphyrin complex (phosphor) dissolved in the solution, which is flashed every 0.1 s with 630 nm light. The concentration of O₂ is a linear function of the decay rate. The instrument is used to study the reaction of dithionite (S₂O₄^2-) with O₂ at 25°C and 37°C. It is found that the ratio of dithionite to oxygen consumed in the reaction is 1.2 ± 0.2 at 25°C and 1.7 ± 0.1 at 37°C, suggesting a temperature-dependent stoichiometry. At both temperatures, the initial rate of O₂ consumption, -d[O ₂]/dt, is found to be 1/2 order in S₂O₄ ^2- and first order in O₂. This finding is consistent with a previously proposed mechanism: S₂O₄^2- ↔ 2SO₂^- comes to a rapid equilibrium, and SO ₂^- reacts with O₂ in the rate-determining step.

Original language	English
Pages (from-to)	1511-1518
Number of pages	8
Journal	Journal of Physical Chemistry A
Volume	112
Issue number	7
DOIs	https://doi.org/10.1021/jp710176z
Publication status	Published - Feb 21 2008
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry

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title = "Oxygen measurement via phosphorescence: reaction of sodium dithionite with dissolved oxygen",

abstract = "A homemade instrument for the measurement of oxygen concentration in aqueous solutions measures the decay rate of the phosphorescence of a Pd-porphyrin complex (phosphor) dissolved in the solution, which is flashed every 0.1 s with 630 nm light. The concentration of O2 is a linear function of the decay rate. The instrument is used to study the reaction of dithionite (S2O42-) with O2 at 25°C and 37°C. It is found that the ratio of dithionite to oxygen consumed in the reaction is 1.2 ± 0.2 at 25°C and 1.7 ± 0.1 at 37°C, suggesting a temperature-dependent stoichiometry. At both temperatures, the initial rate of O2 consumption, -d[O 2]/dt, is found to be 1/2 order in S2O4 2- and first order in O2. This finding is consistent with a previously proposed mechanism: S2O42- ↔ 2SO2- comes to a rapid equilibrium, and SO 2- reacts with O2 in the rate-determining step.",

author = "Zhimin Tao and Jerry Goodisman and Souid, {Abdul Kader}",

year = "2008",

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T1 - Oxygen measurement via phosphorescence

T2 - reaction of sodium dithionite with dissolved oxygen

AU - Tao, Zhimin

AU - Goodisman, Jerry

AU - Souid, Abdul Kader

PY - 2008/2/21

Y1 - 2008/2/21

N2 - A homemade instrument for the measurement of oxygen concentration in aqueous solutions measures the decay rate of the phosphorescence of a Pd-porphyrin complex (phosphor) dissolved in the solution, which is flashed every 0.1 s with 630 nm light. The concentration of O2 is a linear function of the decay rate. The instrument is used to study the reaction of dithionite (S2O42-) with O2 at 25°C and 37°C. It is found that the ratio of dithionite to oxygen consumed in the reaction is 1.2 ± 0.2 at 25°C and 1.7 ± 0.1 at 37°C, suggesting a temperature-dependent stoichiometry. At both temperatures, the initial rate of O2 consumption, -d[O 2]/dt, is found to be 1/2 order in S2O4 2- and first order in O2. This finding is consistent with a previously proposed mechanism: S2O42- ↔ 2SO2- comes to a rapid equilibrium, and SO 2- reacts with O2 in the rate-determining step.

AB - A homemade instrument for the measurement of oxygen concentration in aqueous solutions measures the decay rate of the phosphorescence of a Pd-porphyrin complex (phosphor) dissolved in the solution, which is flashed every 0.1 s with 630 nm light. The concentration of O2 is a linear function of the decay rate. The instrument is used to study the reaction of dithionite (S2O42-) with O2 at 25°C and 37°C. It is found that the ratio of dithionite to oxygen consumed in the reaction is 1.2 ± 0.2 at 25°C and 1.7 ± 0.1 at 37°C, suggesting a temperature-dependent stoichiometry. At both temperatures, the initial rate of O2 consumption, -d[O 2]/dt, is found to be 1/2 order in S2O4 2- and first order in O2. This finding is consistent with a previously proposed mechanism: S2O42- ↔ 2SO2- comes to a rapid equilibrium, and SO 2- reacts with O2 in the rate-determining step.

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Oxygen measurement via phosphorescence: reaction of sodium dithionite with dissolved oxygen

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