![]() ![]() ![]() Hematite still plays an important role in the field of pigments, and people are also making great efforts to improve its color, stability, cost, and environmental friendliness. Hematite is one of the most widely used red mineral pigments because of its abundant resources in nature and changeable color, whose use can be traced back to the Anthropolithic Age. In ancient times, the commonly used pigments are mainly natural minerals, such as hematite (α-Fe 2O 3), cinnabar (α-HgS), realgar (As 4S 4), cadmium sulfide (CdS 1−xSe x), and Egyptian blue (CaCuSiO 10). Pigments make the world in a variety of colors and play an important role in the process of human civilization, which have been used widely in the manufacture of ceramics, sculptures, lacquer wares, and paintings. The iron-red hybrid pigment derived from illite (ILL) clay showed the best red color performance with the color values of L* = 31.8, a* = 35.2, b* = 27.1, C* = 44.4 and h° = 37.6, and exhibited excellent stability in different chemical environments such as acid, alkaline, and also in high-temperature conditions. The clay minerals with higher surface activity are more suitable to prepare iron-red pigments with better performance. The color properties of iron-red hybrid pigments are closely related to the surface charges, surface silanol groups, and solid acid sites of clay minerals. Meanwhile, they also act as the “micro-reactor” for forming Fe 2O 3 crystals and the supporter for inhibiting the aggregation of Fe 2O 3 nanoparticles. ![]() The results showed that the clay minerals act as green precipitants during the hydrothermal reaction to induce in-situ transformation of Fe(III) ions into Fe 2O 3 crystals. The influence of structure, morphology and composition of different clay minerals on the structure, color properties, and stability of the pigments was studied comparatively by systematic structure characterizations with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmittance electron microscope (TEM), X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS) and CIE- L*a*b* Colorimetric analyses. A series of environment-friendly clay minerals-α-Fe 2O 3 iron-red hybrid pigments-were prepared by a simple one-step hydrothermal reaction process using natural nanostructured silicate clay minerals as starting materials. ![]()
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