Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Properties of water in calcium- and hexadecyltrimethylammonium-exchanged bentonite
Autore:
Anderson, MA; Trouw, FR; Tam, CN;
Indirizzi:
Univ Calif Riverside, Dept Soil & Environm Sci, Riverside, CA 92521 USA Univ Calif Riverside Riverside CA USA 92521 Sci, Riverside, CA 92521 USA Argonne Natl Lab, Intense Pulsed Neutron Source, Argonne, IL 60439 USA Argonne Natl Lab Argonne IL USA 60439 utron Source, Argonne, IL 60439 USA
Titolo Testata:
CLAYS AND CLAY MINERALS
fascicolo: 1, volume: 47, anno: 1999,
pagine: 28 - 35
SICI:
0009-8604(199902)47:1<28:POWICA>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
2ND HARMONIC-GENERATION; ELASTIC NEUTRON-SCATTERING; ORGANIC-COMPOUNDS; PARA-NITROPHENOL; ADSORBED WATER; CLAYS; AIR; MONTMORILLONITE; CHLOROPHENOLS; INTERFACE;
Keywords:
bentonite; diffusion; HDTMA; neutron scattering; water;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Physical, Chemical & Earth Sciences
Citazioni:
28
Recensione:
Indirizzi per estratti:
Indirizzo: Anderson, MA Univ Calif Riverside, Dept Soil & Environm Sci, Riverside, CA92521 USA Univ Calif Riverside Riverside CA USA 92521 de, CA 92521 USA
Citazione:
M.A. Anderson et al., "Properties of water in calcium- and hexadecyltrimethylammonium-exchanged bentonite", CLAY CLAY M, 47(1), 1999, pp. 28-35

Abstract

Dynamical and thermodynamic properties of water at room temperature in Ca-and hexadecyltrimethylammonium- (HDTMA) exchanged bentonite were determined for 4 different water contents (similar to 0.03-0.55 g water g(-1) clay). Incoherent quasi-elastic neutron scattering (QENS) was used to measure thetranslational and rotational mobility of water in the clays, while chilledmirror dewpoint psychrometry measured water activity of the samples, differential scanning calorimetry (DSC) provided information about the temperature of dehydration and X-ray diffraction (XRD) quantified layer spacings forthe clays. The neutron scattering data were fit to a jump diffusion model that yielded mean jump lengths, jump diffusion residence times and rotational relaxation times for water in the clays. Mean jump lengths were quite similar for the 2 different cation saturations at equivalent water contents, and decreased with increasing water content. The fitted jump lengths rangedfrom 0.27-0.5 nm and were 2-4 times larger than that found for bulk water (0.13 nm). jump diffusion residence times were 3-30 times longer than that for bulk water (1.2 ps) and also decreased with increasing water content. The residence times were somewhat shorter for HDTMA-clay as compared with Ca-clay at equivalent water contents. Rotational motion was less strongly influenced than translational motion by the presence of the clay surface. The energy state of water in the 2 cation saturations were quite different; dehydration temperatures for the HDTMA-clay were approximately 30 degrees C lower than the Ca-clay at equal water contents, while water activities, as P/P-0, were up to 0.6 units higher. A linear relationship was found between water activity and the translational diffusion coefficient, although at the highest water content, the diffusion coefficient of water for the HDTMA-clay was approximately 30% higher than that measured for bulk water.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 11/07/20 alle ore 19:29:26