Pretoria

i Water-in-oil (w/o) microemulsion systems, stabilised by either an anionic surfactant or a cationic surfactant were studied. The anionic system consisted of ethoxylated nonylphenol phosphate esters (Atpol), Shellsol oil and an alcohol. These microemulsions tolerated an increase in ionic strength of the water phase up to a point: Beyond this point no microemulsion could be obtained. However, adding amine salts, e.g. diethanolamine nitrite, improved the emulsification of the aqueous phase. Increasing the alcohol (cosurfactant) chain length up to octanol also increased the uptake of the aqueous phase. Thus octanol yielded the best results in terms of emulsifying large volumes of the water-phase, particularly at high salt concentrations. A key objective was to prepare stable microemulsions with high nitrite content. The maximum microemulsion nitrite contents (expressed as NaNO2 equivalent by mass) achieved were: About 10 % when a 30 % NaNO2 solution was emulsified 23 % when neat diethyl ethanolamine nitrite (DEEAN) was solubilized, an