Clay-catalyzed phenomena of cationic-dye aggregation and hydroxo-chromium oligomerization

Higher dye aggregates, organized in layers, were catalytically obtained by intercalating C.I. Basic Blue 41 into montmorillonite and bentonite at very high dye:clay ratios, i.e., larger than 200% of the cation exchange capacity (CEC). Further oligomerization of the chromium oligomers, inserted into montmorillonite intercalated with hydroxo-chromium complexes, was also recognized as clay-promoted. Formation of higher agglomerates proceeding through interactions with the host aluminosilicate suggests that the clays act as aggregation catalysts equally with organic and inorganic compounds. Scanning electron microscopy (SEM) was employed to examine the microstructure of the hybrid materials constructed; both high-order assemblies of the monoazo-cationic dye and higher Cr(III) oligomers characteristically modify the surface morphology of the intercalated clays. (C) 2009 Elsevier Inc. All rights reserved.