Mechanochemical preparation of low-cost cobalt blue composite pigments with good color and acid resistance based on desert sands

The development of a facile cleaner route is important for the preparation of low-cost cobalt blue pigments with high blue chroma. In this study, three desert sands were directly employed to prepare cobalt blue composite pigments via a cleaner CaCO 3 -assisted mechanochemical method followed by a calcining process. The color property, phase compositions, microstructure and acid resistance of composite pigments were studied in combination with the relevant characterization techniques. The results indicated that incorporation of desert sands improved the distribution of CoAl 2 O 4 nanoparticles and reflected more blue light at 430 nm, and thus composite pigments presented excellent color properties ( L* = 38.87, a* = −0.75, b * = −44.75) compared with the pure CoAl 2 O 4 pigments and most reported pigments. Furthermore, the color property of the pigments was related to the chemical compositions of the original desert sands, and the color of the composite pigments could be adjusted by gradient acid etching of desert sands. Meanwhile, the obtained composite pigments exhibited excellent acid resistance and good application properties as painting ink on plain paper. Therefore, this study provided a promising strategy for the preparation of cobalt blue composite pigments with low production cost and cobalt content based on desert sands.