Determining the Effect of pH on Iron Oxidation Kinetics in Aquatic Environments: Exploring a Fundamental Chemical Reaction to Grasp the Significant Ecosystem Implications of Iron Bioavailability

Autor/inn/en	Kirby, Matthew E.; Bullen, Jay C.; Hanif, M. D.; Heiba, Hany Fathy; Liu, Fengjie; Northover, George H. R.; Resongles, Eleonore; Weiss, Dominik J.
Titel	Determining the Effect of pH on Iron Oxidation Kinetics in Aquatic Environments: Exploring a Fundamental Chemical Reaction to Grasp the Significant Ecosystem Implications of Iron Bioavailability
Quelle	In: Journal of Chemical Education, 97 (2020) 1, S.215-220 (6 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Zusatzinformation	ORCID (Kirby, Matthew E.) ORCID (Bullen, Jay C.) ORCID (Hanif, M. D.) ORCID (Heiba, Hany Fathy) ORCID (Liu, Fengjie) ORCID (Northover, George H. R.)
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0021-9584
Schlagwörter	Science Instruction; Chemistry; Science Laboratories; Science Experiments; Laboratory Experiments; College Science; Undergraduate Study; Scientific Concepts; Spectroscopy; Foreign Countries; United Kingdom (London) + Suchen Sie Ihr Suchwort? Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Chemie; Laboratory work; Laborarbeit; Grundstudium; Spektroskopie; Ausland
Abstract	Understanding the controls of the oxidation rate of iron (Fe) in oxygenated aquatic systems is fundamental for students of the Earth and Environmental Sciences as it defines the bioavailability of Fe, a trace metal essential for life. The laboratory experiment presented here was successfully developed and used during a third-year undergraduate lab course at Imperial College London for several years. It employs ultraviolet-visible (UV-vis) spectroscopy calibrated externally with 0 to 50 [mu]M Fe[superscript 2+] standards created in a 492 [mu]M ferrozine and 0.43 M acetate matrix. The students conducted the oxidation experiments in stirred batch reactors at equilibrium with atmospheric oxygen. The solution contained 40.5 [mu]M initial Fe[superscript 2+] concentration and a 5.1 mM imidazole buffer. The pH was adjusted to values between 7.22 and 7.77. The students observed a pseudo-first-order reaction with respect to Fe[superscript 2+] concentration. Plotting the logarithms of the apparent rate constants (k') at different pH values leads to a gradient of 2.2 ± 0.2 min[superscript -1] pH[superscript -1], indicating a second-order reaction with respect to OH[superscript -] concentration, in agreement with published literature. The oxidation reaction occurred rapidly (tens of seconds to tens of minutes) indicating that in oxygenated aquatic systems, Fe[superscript 3+] will be the dominant oxidation state, significantly reducing the bioavailability of Fe. The simple laboratory experiment presented here allows the students to learn about kinetic parameters for a fundamental chemical reaction. It allows the students to explore the significant implications this has for aquatic ecosystems. (As Provided).
Anmerkungen	Division of Chemical Education, Inc. and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2024/1/01