Hostname: page-component-7b7567c8c-mnklg Total loading time: 0 Render date: 2026-11-12T10:55:59.077Z Has data issue: false hasContentIssue false

Complexes vermiculite—aminoacides

Published online by Cambridge University Press:  09 July 2018

J. A. Rausell-Colom
Affiliation:
Instituto de Edafologia y Biologia Vegetal. C.S.LC. Madrid, España
P. S. Salvador
Affiliation:
Instituto Geologico y Minero de España, Madrid

Abstract

Vermiculite single crystals immersed in aminoacid solutions of varying concentration and pH, form complexes characterized by discrete basal spacings. Organic molecules enter in the interlayer space as cations and as dipolar ions through mechanisms of ion exchange and dipole adsorption.

The basal spacings of the complexes were recorded. Based on these results the possible arrangements of the aminoacid molecules have been discussed.The main assumptions used are: (a) the electropositive groups NH3 + penetrate into the holes formed by the basal oxygens of the silicate; (13) the C-N bonds are perpendicular to the silicate sheets; (c) the hydrogen atoms of the —CH2 groups are directed towards the sheet surfaces; (d) the —COO− and —COOH groups are located in the middle plane of the interlayer space, halfway between the negative structural charges; and (e) double hydrogen bonds are formed between —COOH groups belonging to organic cations adsorbed onto opposite surfaces.

In solutions of higher concentration the crystals swell to the gel state. This phenomenon is due to: (a) the different nature of interlayer cohesion after substitution of the inorganic cations by the aminoacid cationic form; and (b) the appearance of repulsive forces between —COO− groups of adsorbed dipoles, that overcome cohesive forces.

Information

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1971

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable