Properties of acid or alkali treated cadmium pigments
2013
Makarewicz, Edwin | Cysewski, Piotr | Michalik, Agnieszka | Ziółkowska, Dorota
Series of cadmium pigments were chemically modified by immersion in acidic and basic conditions. Many changes were documents both for structure and properties of CdS pigments doped with CdSe or ZnS. There were consistently observed changes in saturation of red and a decrease in green hue for sRGB values regardless of the acidity of digesting mixtures. Higher sensitivity to aggressive environment for pigments with higher CdSe doping was noticed. However, linear trend was broken after reaching 1:1 ratio of CdS: CdSe behind which again pigment were less prone to chemical digestion. The structural changes were described by thermogravimetric, methyl blue absorption and RTG diffraction studies. The acidic and basic conditions lead to change of increase of crystalline phase by digesting mainly amorphous part. This in turn resulted in changes of active adsorption sites increasing yellow pigment specific surface after alkaline treatment and decreasing it due to acidic condition. During pigments digestion in acidic and alkaline conditions their amorphous forms are removed from them which causes an increase in the number of active centers of adsorption.
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