Abstract:

The properties of potassium saponified 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (HEHPEHE or P507) as well as the formation of microemulsions (water/(K,H )EHPEHE/n-heptane)have been investigated by means of Fourier Transform Infrared Spectroscopy(FT-IR).The stretching bands of P-O-H and the P-O-C shift with the saponification due to the interaction of HEHPEHE and the saponified resultant (KEHPEHE), named acid-salt system. The absorbance of P-O-H stretching vibration varies to lower frequencies while P-O-C stretching band shifts to higher wavenumbers with the increases of saponification. Furthermore, the P-O-C stretching band splitted into two distinct peaks after the saponification exceed 60%.Water/(K,H) EHPEHE/n-heptane microemulsions could be formed when the saponification was higher than 60% . The water solubility and the average diameter of droplets in microemulsion reach their maxima at the saponification of 75%.

Key words: 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester(HEHPEHE or P507), Microemulsions, Acid-salt system, FT-IR, Laser-scattering