Bentonite minerals and its TGA, DSC and PXRD studies

Department of Chemistry, G. B. College, (T.M. Bhagalpur University), Naugachia-853 204,
Bihar, India
E-mail : ashokjha39@gmail.com
Manuscript received 04 August 2014, revised 06 January 2016, accepted 06 January 2016

Bentonite is hydrated alumina-silicate clay composed of the smectite class mineral Montmorillonite. The deposits are widely distributed in Rajmahal Hills of Jharkhand. A large number of samples collected from different places available in different colours revealed the fact that they are good ion exchangers. Some of them gave positive stain test with benzidine. Percentage of alumina and silica known for different samples accounted for different adsorption behaviour. These clay minerals have a layered structure based onsheets with 6-membered rings of silica tetrahedral formed by the condensation of sheets of silica tetrahedral with sheets of Al or Mg octahedra. Investigations on thermal behaviour carried out using TGA, DSC experiments present almost a loss of mass about 18.9% showing the loss of molecular water and dehydroxylation. X-Ray diffraction patterns of the samples consist peaks of Montmorillonite minerals. The mineral has been considered to constitute an interstratified mineral with a structure composed of Kaolin and Montmorillonite layers. The proportion of Montmorillonite layers is abundant in the inner part, but at the margin the layers of Kaolin are present.