Document Detail

Alterations of the surface and morphology of tetraalkyl-ammonium modified montmorillonites upon acid treatment.
MedLine Citation:
PMID:  21820667     Owner:  NLM     Status:  Publisher    
The effect of short alkyl chain cations on the modification of the structure, surface and textural properties of organo-montmorillonites upon their acid treatment was investigated. Samples prepared from Ca-SAz montmorillonite and tetramethylammonium (Me(4)N(+)-), tetraethylammonium (Et(4)N(+)-), tetrapropylammonium (Pr(4)N(+)-) and tetrabutylammonium (Bu(4)N(+)-) salts were treated in 6M HCl at 80°C for 2-8h and analyzed by different methods. Acid treatment of organo-montmorillonites caused gradual release of Al and Mg from the octahedral sheets and destruction of their layered structure. The extent of the changes depended significantly on the size of organo-cation. While large plate-like particles of Ca-SAz and Me(4)N-SAz were disintegrated during acid treatment and smaller fine grains were created, the morphology of Bu(4)N-SAz was modified only slightly. Pore size analysis showed generation of pore network upon organo-montmorillonites dissolution. After longer acid attack, pore volume increased and pore size distribution curves were shifted to pores with diameter above 25Å. The surface area of acid-treated samples increased due to destruction of the montmorillonite layers and formation of the SiO(2)-rich reaction product. The highest value 475m(2)/g was observed for Me(4)N-SAz treated 4h. Surface area of Et(4)N-SAz, Pr(4)-SAz and Bu(4)N-SAz was 441, 419 and 293m(2)/g, respectively, after 8h treatment. Similar decomposition level was observed for Ca-SAz and Me(4)N-SAz, and less destruction was found for Et(4)N-SAz, Pr(4)-SAz and very low for Bu(4)N-SAz. Though Bu(4)N(+) is short alkyl chain cation, its size is large enough to cover the inner and outer surfaces of montmorillonite and thus to protect the clay layers from acid attack.
Helena Pálková; L'uboš Jankovič; Małgorzata Zimowska; Jana Madejová
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-7-20
Journal Detail:
Title:  Journal of colloid and interface science     Volume:  -     ISSN:  1095-7103     ISO Abbreviation:  -     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-8-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043125     Medline TA:  J Colloid Interface Sci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava, Slovakia.
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