Chloritization of Montmorillonite by Its Coprecipitation with Magnesium Hydroxide

G. C. Gupta* and W. U. Malik
University Chemistry Department, Roorkee, India
* Present Address: School of Engineering, University of Mississippi, University, Mississippi.

Abstract: A magnesium hydroxide-montmorillonite complex prepared at an OH/Mg molar ratio of 2 (16 meq Mg/g clay) and immediately cleaned of any free Mg(OH)2 behaves like magnesium-chlorite and shows no change during 3 months ageing. Magnesium hydroxide completely precipitates within the interlayer space of montmorillonite. X-ray diffraction analysis, thermal (DTA and TGA) studies, i.r. absorption analysis, polarographic reduction behaviour, and cation exchange capacity measurements confirm the transformation of montmorillonite to a chlorite-like structure. Further ageing of the complex results in the release of brucite from the interlayer space and expansion of the complex on glycerol treatment. X-ray analysis of the 6 months aged sample shows the presence of free brucite but not montmorillonite. A small but significant increase in CEC of the complex is observed on ageing. When the Mg(OH)2-montmorillonite complex is allowed to age in the presence of free Mg(OH)2 (external to montmorillonite unit layers) in a dry state, a “seeding” effect takes place and the “fixed” Mg(OH)2 starts coming out from the interlayer space after 10 days.

Clays and Clay Minerals; December 1969 v. 17; no. 6; p. 331-338; DOI: 10.1346/CCMN.1969.0170602
© 1969, The Clay Minerals Society
Clay Minerals Society (www.clays.org)