The Synthesis And Characterization Of Metal Ion-Doped α-Alumina Oxide Pigments

Textile industry generates a great quantity of wastewater with high concentration pollutant. Water pollution is a serious threat to ecological environment, especially to the water environment. Printing and dyeing wastewater pollution is most serious, which increase environmental pressure and increase the shortage of water resources. So it is necessary to solve pollution problems in printing and dyeing wastewater. The development of new technologies-anhydrous printing and dyeing caused widespread concern. However, the melt spinning process temperature is above 200℃, and many organic dyes, pigments degrade easily at high temperatures and produce toxic or harmful substances. Traditional inorganic pigments contain a lot of heavy metals, such as lead chromate, cadmium sulfide, etc. which is harmful to human health and pollutes the environment; and its application has been very limited. To decrease the emission of pollutant in printing and dyeing industry, it is obliged to develop new non-aqueous dyeing techniques.This article proposes to develop a new type of doped metal oxide pigments. The novel mixed metal oxide pigments use a-alumina as matrix. In the present work, aluminum chloride and various soluble salts of doped ions were dissolved in water. In addition, urea and polyvinyl pyrrolidone(PVP) were also dissolved in the above aqueous solution under supersonic treatments. Then the solutions were heated to induce the hydrolysis of urea so that soluble aluminum and doped ions covert into insoluble hydroxide or carbonate gels. After calcinations, the obtained gels change mixed metal oxide pigments whose color are related to type and concentrations of the doped ions. XRD characterization demonstrated that the diffraction patterns of the products are the same as that ofα-alumina. Diffuse reflectance spectra of samples of the samples in UV-Vis regions showed that the absorption bands for d-d transitions of the doped ions undergo considerable change as the coordinate environments changes. In addition, L*, a* and b* value of the pigments were measured by using UV-Vis densitometer. SEM results indicated that the sizes of the pigment powders are in the range 200-300nm. ICP test showed that very little amount of doped metal ions occur in the corresponding filtrate, indicating that the new pigment exhibits good chemical stability. The above results suggest that these new kinds of mixed metal oxide pigments are stable, benign to environment, and may provide a new chance for non-aqueous printing and dyeing industry.