Adsorbents saponite

Although the possible catalytic applications of PILCs is the subject more extensively studied, large efforts have also been devoted to the characterisation of the microporous structure of these materials. To this end, the application of both classical and novel models based on gas adsorption has been reported in the literature. The adsorption data depend on the internal physical and chemical structure of the solid and on the nature of the adsorbate molecule. Thus, the adsorption results contain information about structural and energetic properties of the materials surface [8]. In the following, the methods considered in this work to investigate the microporous properties of several alumina-pillared saponites are briefly presented. 

The adsorption and redox of metal complexes on clay-modified electrodes were examined by Yao et al. [94]. The species adsorbed on a saponite clay film by the exchange with a hydrated sodium ion in the clay film were identified from the mass change and absorbance change of the metal complexes in solution as follows [Ru(bpy)3] +1/2S04 for racemic body, [Ru(bpy)3] + and [Ru(bpy)3] " l/2S04 for enantiomers, and [Ru(NH3)6] +-S04 . The EQCM results revealed that one [Ru(bpy)3] + molecule was eliminated from the clay film when three [Ru(bpy)3] + ions were oxidized [95]. The charge balance during the redox reactions was accomplished by the transport of S04 and Na" " in the cases of [Ru(NH3)6] + and [Fe(CN)6] . The adsorption and redox of [Fe(CN)6] on an anionic clay-modified electrode (hy-drotalcite) were also examined [96]. 

FIGURE 7 Luminescence spectra of [Ru(bpy)3] -Na-saponite intercalation compounds (a) before and (b) after intercalation of C12AO surfactant. The adsorbed amounts of [RuCbpyls] and C12AO are 1 and 400 mmol/100 g clay, respectively. (From Ref 54. Copyright 1998 American Chemical Society.)... 

Changes in the aggregation state of y-stilbazolium [4-(2-phenylvinyl)pyri-dinium] ion on saponite by coadsorption of alkylanunonium ions (C N+) has been investigated (222). Figure 32 shows the effect of CgN+ on photoreactivity of preintercalated stilbazolium ions on clay. On coadsorbing longa- than the stilbazolium ion, the major photoreaction was changed from cyclodimerization to E-Z isomerization and the excimer emission of the intercalated stilbazolium ions was dramatically reduced. The formation of dimers or clusters of adsorbent were simulated by a Monte Carlo method for a two-dimensional lattice. 

Figure 13 Sedimentation ratio (Fdcar liquid/Fi ,ai) vs. yield stress at a field strength of 2000 V/mm for samples containing 0.05g/ml of hydrophobically modified saponite (adsorbed surfactant (Ci6)2f>MABr) and different additives in 7-hex.adecanc. The type and concentration of additives are listed in the legend. All samples stood 1 day at rest before the sedimentation ratio was measured. Reproduced with permission from T. Diirrschmidt, and H. Hoffmann, Colloids and Surfaces A, 156(1999)257.

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