IONTOVÁ VÝMĚNA V POČÁTEČNÍCH STÁDIÍCH INTERAKCE ŽIVEC–VODA

Roč.22,č.1-2(2015)

Markéta Camfrlová Karel Vybíhal Jiří Faimon

https://doi.org/10.5817/GVMS2015-1-2-44

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Abstrakt
The sample of perthitic alkali feldspar (62.5 wt. % of KAlSi3O8 and 37.5 wt. % of albite, Na0,996Ca0,004Al1,004Si2,996O8) was dissolved in a special stirred batch reactor (polyethylene vessel of 5 liter volume situated horizontally and rotating at few rotations per hour). The reactor was opened to atmosphere (log PCO2 ~ -3.5) through the mouth at the vessel axis. During the experiment, pH was monitored by pH-meter with combined glass electrode. Solutions were analyzed for Si, Al (spectrophotometry), K, Na (flame AAS), and Ca (ICP-OES). The results showed a fast preferential leaching of alkaline cations with respect to both Al and Si during the early stages of experiment that was diminishing during more advanced stages of the experiment. The released cations exceeded the consumed H+ ions by the range of two up to four magnitudes. The preponderance of cations over H+ ions was especially apparent during few initial days, when the buffering by atmospheric CO2 was insufficient. Simulation of the process by the PHREEQC code covering the CO2 buffering indicated that system feldspar–water–CO2(g) was evolving near the equilibrium in open system during the period after 5th day of the experiment. The results suggested that the mechanism of feldspar dissolution during the initial stages of the process does not correspond to a simple ion exchange and that it is more complicated.

Klíčová slova:
feldspar dissolution; ion exchange; alkali metals/H ratio; dissolution; PHREEQC simulation
Reference

Appelo, C. A. J. – Postma, D. (2005): Geochemistry, Groundwater and Pollution, 2nd edition. – A. A. Balkema Publishers, Leiden.

Casey, W. H. – Westrich, H. R. – Arnold, G. W. (1988): Surface chemistry of labradorite feldspar reacted with aqueous solutions at pH = 2, 3, and 12. – Geochimica et Cosmochimica Acta 52, 2795–2807. https://doi.org/10.1016/0016-7037%2888%2990147-0">https://doi.org/10.1016/0016-7037(88)90147-0

Chou, L. – Wollast, R. (1985): Steady-state kinetics and dissolution mechanisms of albite. – American Journal of Sciences 285, 963–993.

Dougan, W. K. – Wilson, A. L. (1974): Absorptiometric determination of Al in water – comparison of some chromogenic reagents. – Analyst 99, 413–430. https://doi.org/10.1039/an9749900413">https://doi.org/10.1039/an9749900413

Hellmann, R. – Dran, J. C. – Della Mea, G. (1997): Characterization of leached and hydrogenenriched layer formed at 300 °C using MeV ion beam techniques. – Geochimica et Cosmochimimica Acta 61, 1575–1594. https://doi.org/10.1016/S0016-7037%2897%2900022-7">https://doi.org/10.1016/S0016-7037(97)00022-7

Parkhurst, D. L. – Appelo, C. A. J. (1999): User´s guide to PHREEQC (Version 2): A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. – U. S. Geological Survey. Water-Resources Investigations Report 99–4259, 1–312.

Truesdale, V. W. – Smith, C. J. (1976): The automatic determination of silicate dissolved in nature fresh water by means of procedures involving the use of either α- or β-molybdosilicic acid. – Analyst 101, 19–31. https://doi.org/10.1039/an9760100019">https://doi.org/10.1039/an9760100019

Zhu, C. – Veblen, D. R. – Blum, A. E. – Chipera, S. J. (2006): Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization. – Geochimica et Cosmochimica Acta 70, 4600–4616. https://doi.org/10.1016/j.gca.2006.07.013">https://doi.org/10.1016/j.gca.2006.07.013

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