Experimental Study Assessing the Role of Sedimentary Organic Materials to Control the Redox State of Ground Materials to Control the Redox State of Groundwater: Consumption of Dissolved Oxygen by Humic Acid |
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Authors: | Ken-ichiro Haysahi Hideyuki Shibata Mikazu Yui Hiroshi Ohmoto |
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Institution: | Department of Mineralogy, Petrology, and Economic Geology, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980–8578, Japan [e-mail: ];Waste Technology Development Division, Tokai Works, Nuclear Cycle Development Institute, Muramatsu, Tokaimura 319–1194, Japan;Department of Geosciences, The Pennsylvania State University, University Park, PA16802, U.S.A. |
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Abstract: | Abstract: A total of 189 runs were completed to determine the rate of dissolved oxygen consumption in water by the reaction humic acid at 25°, 45°, and 65°C. Glass vial bottles were used as reaction vessels, and humic aicd and pure water of different intitial O2 concentration was loaded with humic acid/water weight of 0.008 and 0.009. Vials were opened periodically to measure O2 concentrations. The pH of the solution fluctuated in the early stages of the experiments and gradually decreased to a constant value. Dissolved oxygen concentration decreased, for example, from initial value of 12 mg/l to 9 mg/l at 25°C, to 5 mg/l at 45°C, and to 2 mg/l at 65°C after the reaction of 500 hours. Analyses of rates suggest that the reaction is first order, and rate constants are 8.42 × 10-9 at 25°C, 2.22 × 10-8 at 45°C, and 1.28 × 10-7 moles m-2 s-1 at 65°C. |
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Keywords: | humic acid reductant nuclear waste repository dissolved oxygen reaction rate |
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