高岭石粒度对Pickering乳液稳定性的影响

Effect of Kaolinite Particle Size on Stability of Pickering Emulsion

固体乳化剂颗粒粒径是影响Pickering乳液稳定性的重要因素。本文以去离子水为水相,液体石蜡为油相,高岭石为乳化剂制备水包油型Pickering乳液,研究了高岭石粒度对乳液稳定性的影响。结果表明:高岭石颗粒与乳液液滴大小之间的匹配特征不仅影响乳化剂与乳液分散相表面之间的作用强度,而且影响其在连续相中形成网络结构的特征,进而影响乳液稳定性。高岭石粒度对乳液稳定的影响存在最佳值,当高岭石颗粒粒度D90值为1. 42μm时,乳液粘度为378 m Pa·s,乳液液滴粒径均匀,乳化剂颗粒在油水界面有序紧密分布,颗粒在连续相所形成三维网络结构趋于牢固,乳液稳定性好。当乳化剂颗粒粒度较小时,体系中的颗粒易受布朗运动因素影响,乳液液滴聚并速度快,乳液粘度低;而当乳化剂颗粒粒度较大时,油水界面上以及连续相中的颗粒易受自身重力的影响发生沉降,破坏三维网络结构,导致乳液粘度降低,乳液稳定性变差。

The size of Pickering particles has important effect on the stability of Pickering emulsion. In this paper, oil-in-water Pickering emulsion was prepared by using deionized water as water phase, liquid paraffin as the oil phase, and kaolinite as the emulsifier. Effect of kaolinite particle size on the emulsion stability was investigated. The results show that the matching characteristics between the kaolinite particle size and the droplet size of the emulsion not only affected the interaction between the emulsifier and the surface of the dispersed phase of the emulsion, but also affected the characteristics of the network structure in the continuous phase, which ultimately affected the emulsion stability. There was an optimum value of kaolinite particle size for effect on emulsion stability. When the particle size D 90 of kaolinite is 1.42 μm, the distribution kaolinite emulsifier is ordered at the oil-water interface with uniform emulsion droplet size, and the three-dimensional network structure of the particles in the continuous phase tends to be firm and stabile. The viscosity of such emulsion is of 378 mPa·s with a high stability. When the particle size of the emulsifier is smaller than the optimum value, the emulsion droplets are easy to aggregate with a low viscosity because of Brownian motion of the particles in the system. Furthermore, when the particle size of the emulsifier particles is much larger than the optimum value, the particles at the oil-water interface and in the continuous phase are susceptible to sedimentation due to the influence of the gravity, which destroys the three-dimensional network structure, resulting in a decrease of emulsion viscosity and a deterioration in emulsion stability.