New Zealand allophanes: a structural study
- 1 January 1980
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 76, 2542-2551
- https://doi.org/10.1039/f19807602542
Abstract
Three natural allophane samples from New Zealand, the Egmont, Waxy-Pan and iron-rich Ruapehu, were investigated by infrared spectroscopy, X-ray diffraction and Mössbauer spectroscopy. The specific surface area and the pore sizes of these samples increase as the pretreatment temperature is raised, up to a temperature where a decrease of the surface area and a narrowing of the pores is observed. This can be explained by two competing phenomena: the release of water from the pores and the collapse of other pores. In comparison with the Egmont and Waxy-Pan allophanes, the iron-rich Ruapehu sample contains considerably less pores of sufficient size to accommodate water. Its exceptional chemical composition and the infrared spectra, X-ray diffraction patterns and Mössbauer spectra suggest the presence of a separate, amorphous iron (III) oxide phase in the pores of this allophane.Keywords
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