3.2. Measurement of W/O microemulsion zone for distilled water
A fine microemulsion system should have the characters of stable, broad zone and insensitive to the temperature. The aim to measure the microemulsion zone is to find a proper system to prepare cerium oxide nanoparticles.
Table 1 was the data of microemulsion zone of distilled water.
The microemulsion zone of distilled water (H2O) was measured using cetyltrim ethylamine bromide (CTAB) as a surfactant, butanol as a co-surfactant, and cyclohexane as oil at room temperature. A series of three-component systems was dispensed when cyclohexane concen- tration was unchanged and the molar ratio between butanol and CTAB changed; W/O microemulsion zone was measured based on clear and chaotic exhibition of the microemulsion system when dropping H2O into the solution. Fig. 3 showed the microemulsion zone under the curve. Here, a part of butanol exited as sequential phase and the others constituted interface membrane with CTAB. Seen from the curve in Fig. 3, a high solubilization capacity to H2O was gotten in this microemulsion system when the molar ratio between butanol and
CTAB was 5∼13, and solubilization capacity reached highest in the
range of 9∼13. Thus, microemulsion system was considered the most
stable in this constitution.