A series of environment-friendly clay minerals—α-Fe2O3 iron-red hybrid pigments—were prepared by a simple one-step hydrothermal reaction process using natural nanostructured silicate clay minerals as starting materials. 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. 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 Fe2O3 crystals. Meanwhile, they also act as the “micro-reactor” for forming Fe2O3 crystals and the supporter for inhibiting the aggregation of Fe2O3 nanoparticles. 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. The clay minerals with higher surface activity are more suitable to prepare iron-red pigments with better performance. 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.