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Estimation of free iron oxides in soils and clays by a photolytic method

Published online by Cambridge University Press:  14 March 2018

A. S. de Endredy
A. S. de Endredy*
Affiliation:
Scientific Services Division, Ministry of Agriculture, Kumasi, Ghana
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Abstract

The extraction of naturally occurring free iron oxides from soils and clays with oxalate solutions is distinctly photosensitive. Apparently wave-lengths around 366 mµ, the near ultra-violet region, are the most efficient; this radiation is predominant in the emission of a medium-pressure mercury arc lamp. A qualitative consideration of the dissolution process indicates that in all probability electron transfer from solute to solid via intermediary C2O4− is involved. Such a mechanism may explain the attack of near-neutral oxalate solutions upon natural ferric oxides and the decomposition of the quite resistant hematite in slightly acid media, when irradiated. The reaction appears to be autocatalytic. Electron transfer utilizing thermal electrons may also explain the attack of dithionite ions upon ferric oxides, which was shown to proceed in media above neutrality. Finally, a detailed description of the method is given, including the application for estimating free iron oxides in particle-size fractions obtained during the course of mechanical analysis.

Type
Research Article
Information
Clay Minerals Bulletin , Volume 5 , Issue 29 , July 1963 , pp. 209 - 217
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1963

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