Dear Dr. Parkhurst: I did some experiments to determine at a bench scale, reduction of Cr(VI) in a contaminated groundwater by adding Fe(II) through electrolysis. In such an experiment, an iron electrode is immersed into a beaker containing the contaminated groundwater, electricity is passed through the electrodes, aqueous Fe(II) is directly added to the solution and Cr(VI) is reduced to Cr(III). No oxygen is bubbled through the beaker but there was no special arrangement to do the experiments in a particularly reducing environment to eliminate the competition between the oxidation reaction of Fe(II) to Fe(III) and reduction of Cr(VI) to Cr(III). When I am trying to calculate the equilibrium species distributions using Phreeqc, I see dramatic difference in the results if I use EQUILIBRIUM_PHASES O2(g) -0.68 to denote that the water is open to atmospheric partial pressure of oxygen and if I don't use this key word. My question is, for the experiment described above, is using the key word EQUILIBRIUM_PHASES with O2(g) Partial Pressure (10^-0.68) the correct approach. I enclose the input file and the database [modified phreeqc.dat as phreeqcc.dat to include all Cr(VI) and Cr(III) species] for your viewing. Please advise. <<PR_MW_15_Fe_1X_c.pqi>> <<phreeqcc.dat>> With kindest regards, Biswajit Biswajit Mukhopadhyay, M. S., M. E., Ph. D., D. Sc. Senior Hydrologist & Geochemist ecology and environment, Inc. International Specialists in the Environment biswajitm@xxxxxxx Phone: 214-245-1051 www.ene.com Office Address: 1200 Main Street, Suite 500 Dallas, TX 75202 USA
Attachment:
PR_MW_15_Fe_1X_c.pqi
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Attachment:
phreeqcc.dat
Description: Binary data
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