Insolubilization of Anionic Dyes by Fixing in Chitosan/Smectite Composite System (I):Adsorption of FD & C Dyes on Chitosan/Montmorillonite Composite Substrates
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概要
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Anionic dyes can be fixed in chitosan/smectite composite system to give water-insoluble colored materials, which are applicable as pigments harmless to human body when FD & C dyes are used as the anionic dyes. In order to prepare the colored materials, two types of processes, 2- and 1-step ones, were tried. In the 2-step process, chitosan/smectite composite substrate prepared by mixing chitosan acetate solution and Na-montmorillonite suspension was separated, dried and powdered in the 1 st step, and then in the 2 nd step was redispersed in 0.5% acetic acid solution and treated by anionic dyes. In the 1-step process, the composite substrate formed in the suspension was not separated and dyed in situ.<BR>The composite substrate in the 2-step process had chitosan intercalated between the silicate layers as single layer or double layers. The double-layer structure was found to be capable of adsorbing anionic dyes, while the single-layer one was not. The layer structure was maintained throughout with the basal spacings expanded by the dye adsorption. On the other hand, the 1-step process gave products poorer in the structural order, but richer in the dye content and stronger in eluting resistance of the dye in salt water. Pigment properties were compared with commercial FD & C aluminum lakes.
- Japan Society of Colour Materialの論文