Abstract:
Commercial smectites (montmorillonite, hectorite and bentonite) and kaolin clays were purified by fractionated sedimentation with fraction 3COOH and CH3CH2OOOH) 20 % (V/V, 10mL) were examined refractometrically using 0.05g of each clay sample in 14mL vials at room temperature. The experimental results proved that hectorite i.e., trioctahedral magnesium smectite showed preferential adsorption of water from aqueous phase of carboxylic acids. Smectites (0.5 %) expanded and changed into jelly-like forms and kaolin formed a swollen paste in the aqueous carboxylic acids in vials. The sizes of the cylindrical shaped jells of smectites formed depend on the layer charge density, location of charge, size of carboxylic acid and nature of the interlayer cation and its hydration properties, were in the following order. Li-montmorillonite > Na, Ca-montmorillonite > Na-bentonite > Li-bentonite > Na-hectorite ≈ Li-hectorite. It was also observed that the cylindrical shaped jells of the clays formed were largest in the aqueous propionic acid. The 0.5 % by weight of commercial clays formed slurries while pure clays changed to suspensions in deionized water in vials under similar conditions. The interactions of the water and carboxylic acids with the interlayer cations and the exposed smectite clay surface are responsible for the swelling due to the expansions of the interlayers from its dry state.
Page(s):
546-558
DOI:
DOI not available
Published:
Journal: Journal of Chemical Society of Pakistan, Volume: 30, Issue: 4, Year: 2008