Showing papers in "Clay science in 2009"

Adsorption of aromatic compounds in water by talc.

Abstract: The adsorption from water of two model aromatic hydrocarbons, benzene and toluene, by talc has been investigated. Complete adsorption was achieved within five hours of mixing the reactants. Both benzene and toluene gave linear isotherms. The slope of the isotherm for toluene was steeper than that for benzene, indicating that toluene had a greater affinity for talc. The adsorption capacity of talc for benzene and toluene was similar to that of tetramethylphosphonium (TMP)- and tetramethylammonium (TMA)-montmorillonite. However, more benzene and toluene were adsorbed by talc than by a mesoporous silica (FSM-16).

Surface analysis and frictional force measurement of the shear surface at the residual state of clay by AFM.

Abstract: In this research paper the residual strength of clay is deemed to correspond to the total value of the strength of the soil particles used in the specimen. The frictional force of the soil particles was measured by using Atomic Force Microscope (AFM); then the frictional force and the residual strength of the specimen were compared. The surface profile of the shear surface in residual state, the friction coefficient, the velocity de­ pendency of frictional force and the adsorptive force of clay adsorbed water were measured by AFM in micro area. As a result, although the shear surface appeared flat to the naked eye, it actually turned out to be rough. The increase of the frictional force in micro area was proportional to the increase in the vertical stress, and the increase rate or angle of friction [

Proton NMR studies on rhodamine B in an aqueous clay suspension.

Abstract: The dynamics of rhodamine B (RB) in D 2 O solutions was examined in the absence and presence of a smec- tite clay mineral, synthetic sodium-saponite (SSA), by 1 H nuclear magnetic resonance (NMR) spectroscopy. Hybridization of RB with the exfoliated SSA particles significantly decreased the intensity of NMR resonance signals of RB protons with the linewidth broadening, compared to RB alone. This indicated that the dynamics of RB molecules adsorbed onto the surface of SSA clay particles was very slower than in free state. The photodegradation profiles of RB in the presence of SSA clay particles were also monitored by 1 H NMR spectroscopy. After visible light irradiation, nine new resonance signals resulting from reaction products were detected in the 1 H NMR spectrum. The analysis of two-dimensional 1 H- 1 H COSY and TOCSY spectra of the reaction mixture indicated that the ethyl group(s) of RB molecule adsorbed onto the surface of SSA particles was destroyed in the photodegradation process and that not only N-ethylamine (and/or N,N-diethylamine) as a major product but also other chemical species such as acetoaldehyde, acetic acid and formic acid were also produced. The detection of the minor products by NMR indicated the photodegradation of RB dye under the present experimental conditions involves oxidative reaction processes in which RB itself and/or the N-de-ethylation products react with the dissolved oxygen to produce the minor chemical species.