Netreba S. Kinetic regularities of colloid-chemical and nanochemical transformation of iron-oxygen structures in the Fe0(St3)-H2O-O2 system

Influence of physicochemical conditions such as concentration of oxidant, temperature, composition of the dispersive medium on kinetic regularities of formation ultrafine iron compounds in the Fe0(St3)-H2O-O2 system is considered. Their colloid-chemical mechanisms and the role of nanochemical transformations in these processes, including the formation of primary phase - Fe(II-III) layered double hydroxides are analyzed. It is shown by the kinetic calculations that for most reactions the constant of reaction depends exponentially on temperature and is expressed by the Arrhenius equation, activation energy of magnetite formation is calculated by reduction lepidocrocite Е = 21,5 kJ/mol and by magnetite oxidation and transformation Е12 = 16,2 kJ/mol. Electrokinetic properties of the dispersed phase are investigated. The pH of isoelectric points for magnetite particles, cobaltcontaining spinel ferrite and lepidocrocite is defined and it is found that electrostatic stability factor does'nt play a determining role in the stability of their sols. First of all, hydration factor is the determining factor of stability. Optimal conditions of purposeful regulation properties of ultrafine iron-oxygen structures are defined, which helped to develop new recommendations for receiving ultrafine iron-oxygen structures with controlled colloid-chemical properties. Magnetite nanoparticles and cobaltcontaining spinel ferrite, with the size of 50 - 80 nm and 30 - 50 nm respectively, are received, which is a promising material for use as functional materials of bio-medical and technical purpose.