Effect of acid and alkali treatments on surface areas and adsorption energies of selected minerals

Bentonite, biotite, illite, kaolin, vermiculite and zeolite were acidified or alkalized with hydrochloric acid or sodium hydroxide at concentrations of 0.1, 1.0 and 5.0 mole dm-3 at room temperature for two weeks. In acid treatments, dissolution of A1 prevailed over Si and the opposite was observed...

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Bibliographic Details
Published in:	Clays and clay minerals Vol. 50; no. 6; pp. 771 - 783
Main Authors:	Jozefaciuk, Grzegorz, Bowanko, Grzegorz
Format:	Journal Article
Language:	English
Published:	Boulder, CO Clay Minerals Society 01-12-2002 The Clay Minerals Society
Subjects:	Acidification Adsorption Adsorption Energy alkalinity Alkalization bentonite biotite chemical properties chemical reactions clastic rocks clastic sediments clay mineralogy clay minerals Earth sciences Earth, ocean, space effects Exact sciences and technology experimental studies framework silicates geochemistry illite kaolin mica group Mineralogy nitrogen Nitrogen Adsorption rock, sediment, soil sed rocks, sediments Sedimentary petrology sedimentary rocks sediments sheet silicates Silicates Surface Area Vapor vermiculite Water zeolite group experimental studies illite kaolinite X-ray diffraction mica bentonite acidification biotite Surface Area temperature sheet silicates silicates Nitrogen Adsorption framework silicates clastic rocks vermiculite adsorption etching nitrogen dissolution Water Vapor Adsorption concentration sodium hydroxide isotherms alkalinity Adsorption Energy sedimentary rocks zeolite acidity water vapor crystal structure clay minerals alteration Alkalization hydrochloric acid reagents
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Summary:	Bentonite, biotite, illite, kaolin, vermiculite and zeolite were acidified or alkalized with hydrochloric acid or sodium hydroxide at concentrations of 0.1, 1.0 and 5.0 mole dm-3 at room temperature for two weeks. In acid treatments, dissolution of A1 prevailed over Si and the opposite was observed in alkali treatments. The XRD patterns showed severe alteration of the crystal structure after acid treatments, whereas sharpening of the XRD peaks after alkali treatments was observed. Illite and kaolin were most resistant to acid attack. With a few exceptions, the surface areas of the minerals computed from both water and nitrogen adsorption isotherms increased with acid and alkali treatments. With increasing reagent concentration, the nitrogen surface area increased faster than the water surface area. Well-defined trends were not noted in either changes of average water or nitrogen adsorption energies or in relative amounts of adsorption sites, indicating that the effects of acid and alkali attack are controlled by the individual character of the minerals.
Bibliography:	0009-8604(20021201)50:6L.771;1- (QE) Geology
ISSN:	0009-8604 1552-8367
DOI:	10.1346/000986002762090308