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Oxidation of Iron in Biotite by Different Oxidizing Solutions at Room Temperature
Author(s) -
Amonette J.,
Ismail F. T.,
Scott A. D.
Publication year - 1985
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1985.03615995004900030048x
Subject(s) - oxidizing agent , mica , decomposition , chemistry , biotite , redox , ion exchange , inorganic chemistry , ion , materials science , organic chemistry , metallurgy , quartz
Biotite samples (10–20 µm lepidomelane) were mixed with solutions that contained various oxidants (O 2 , NaOCl, H 2 O 2 , or Br 2 ) and salts (NaCl, KCl, NaCl‐NaBPh 4 , or none) to compare the effectiveness with which these solutions oxidize structural Fe 2+ at 25°C when customary procedures and mica samples at different stages of expansion are used. In general, the treatments that minimized interlayer K exchange did not oxidize detectable amounts of Fe 2+ , whereas those causing mica expansion oxidized equivalent fractions of the Fe 2+ if they were given enough time. The rates of Fe 2+ oxidation by the O 2 and NaOCl‐O 2 solutions were very slow in even the expanded mica and were similar enough to suggest the OCl ‐ ions did not contribute to the process under these conditions. The Br 2 and H 2 O 2 treatments, on the other hand, oxidized 97 and 85% of the structural Fe 2+ in a fully expanded mica, respectively, in a 24‐h period. The relative effects of Br 2 and H 2 O 2 solutions probably reflect differences in the oxidants themselves but are confounded by the low pH of the Br 2 solution, NaBPh 4 interactions and H 2 O 2 decomposition. Indeed, all the results make it clear that more distinction needs to be made between the role of the oxidants and the side efects of the solutions and procedures that are used in oxidation experiments.