Preparation And Application Of Monodispersed Emulsions By Ceramic Membrane Emulsification Method

Particle-size control of emulsion is very important for maintaining stability and giving emulsions new functional roles. Uniform emulsion system and regular ceramic material of TiO₂ were prepared using ceramic membrane emulsification technology.In chapter 2, monodispersed O/W emulsions were prepared by the integrated ceramic emulsification apparatus. Toluene was used as the dispersed phase and water as the continuous phase. Sodium dodecyl sulfate (SDS), a kind of anionic surfactant, was used as emulsifier in the continuous phase andα-Al₂O₃ ceramic membrane with pore size of 1.5μm as emulsifying medium. Stirring speed and transmembrane pressure had a great influence on the droplet size of emulsions and its distribution. The flux of the dispersed phase increased linear with the increase of transmembrane pressure. The emulsifier of SDS lowered the interfacial tension effectively between toluene and water and stabilized the droplets against coalescence and/or aggregation. The emulsion with droplet size of 23.6μm was prepared at the stirring speed of 420rpm, the transmembrane pressure of 0.04MPa, the concentration of 2% SDS and the temperature of 20℃. The distribution of droplet size was unimodal and the value of span was 0.689. The flux of the dispersed phase was 25L.m^-2.h^-1 and the interfacial tension between toluene and water (34.28mN.m^-1) was down to 2.80mN.m^-1. The relationship between relative viscosity of the emulsion and the volume fraction of the dispersed phase was expressed with the equation ofμr = 0 .99+4.67φ+42.85φ²at the stirring speed of 224rpm, the transmembrane pressure of 0.04MPa, SDS concentration of 2% and the temperature of 20℃. Viscosity of the emulsions, which increasing with the volume fraction of the dispersed phase in the same droplet size of the emulsions, decreased weakly with the increase of the droplet size of the emulsions.In chapter 3, monodispersed W/O emulsions were prepared and the effect of surfactant on preparing emulsions by membrane emulsification was studied. Kerosene (containing 2% SPAN80) was used as continuous phase and water (containing different type and concentration surfactants) as dispersed phase. By adding cationic surfactant of CTAB into the dispersed water phase, monodispersed emulsions were prepared by the hydrophilic ceramic membrane (ZrO₂) with pore size of 0.16μm. Surfactants could lower the interfacial tension between oil and water and the interfacial tension declined fastest by adding CTAB into the dispersed water phase.