Modification of Bentonite Properties with Iron Oxide Nanoparticles

Powdered materials based on bentonite and a mixed solid solution magnetite/maghemite were synthesized by the chemical coprecipitation method. Scanning electron microscopy, X-ray phase analysis, magnetic measurements, and nuclear γ-resonance spectroscopy were used to characterize the surface and study the physicochemical properties of the resulting compounds. It has been found that bentonite affects the point defects in the magnetite/maghemite crystal lattice, as well as the crystallite size and dislocation density. It has been shown that samples of the bentonite/iron oxide composite are characterized by lower residual magnetization and higher values of the effective anisotropy field strength compared to those detected for Fe3O4/γ-Fe2O3 powder. Based on the Mössbauer spectroscopy data, a conclusion has been made about the localization of Fe2+ ions in the bentonite structure near oxygen vacancies that form octahedral positions.