Preparation of ultradispersed KNO_3 powders in mixed reverse micelles of tergitol NP-4 + AOT by isothermal evaporation crystallization

摘要

The size, composition, and morphology of KNO_3 particles produced under the conditions of isothermal evaporation crystallization were found to depend on the concentration ratios of surfactant in mixed reverse micelles of Tergitol NP-4 + AOT, content of water pseudophase (w_o = 1.1-4.4), concentration of salt (0.8-2.5 M), and temperature (20-40 C). In optimal conditions (w_o = 2.2, T = 35 C), powders with micrometer particles of tubular structure are formed in reverse micellar solutions of Tergitol NP-4 in n-decane. The addition of 0.01-0.05 M AOT results in the splitting of tubes, a 10~3-fold increase in the specific surface area, and formation of whisker-type particles 5-10 μm long and 0.2-0.5 μm thick. We used photon-correlation spectroscopy and a spinning drop procedure, which showed that the addition of AOT to Tergitol NP-4 leads to a decrease in the hydrodynamic diameter of reverse micelles, and interfacial tension passes through the maximum, which increases with growing temperature.