W/O/W型Pickering乳液的制备及稳定性研究

Study on preparation and stability of W/O/W Pickering emulsion

为了研究改性二氧化硅稳定的W/O/W型Pickering乳液的稳定性影响因素,首先采用两种二氧化硅以一步乳化法及两步乳化法分别制备了W/O/W型Pickering乳液,通过显微镜观察乳液结构,结果表明,两步乳化法制备优于一步乳化法。再采用单因素的实验方法,探究了油水体积比、颗粒质量分数等对Pickering乳液储藏稳定性的影响,结果表明,各因素对乳液稳定性均有较大的影响,当油水体积比为6∶4,亲油颗粒质量分数为4%,水乳体积比为8∶2,亲水颗粒质量分数为5%时稳定性最佳。最后通过在不同条件下对颗粒表面电位的测定,研究了pH、盐浓度对乳液稳定性的影响,结果表明,盐浓度因反离子的静电屏蔽作用对乳液稳定性有负面影响,而pH则引起了颗粒表面电位的改变,在pH=6左右的条件下乳液最稳定,pH>7时,颗粒的乳化性能降低,不利于乳液的稳定。

The factors on the stability of W/O/W Pickering emulsions stabilized by modified silica were studied.W/O/W Pickering emulsions were prepared using two kinds of silica through different methods,i.e.,one-step emulsification method and two-step emulsification method.The structure of the emulsion was observed by microscopy.The results showed that W/O/W Pickering emulsion prepared by two-step emulsification method was better than the one prepared by one-step method.The effects of oil-water volume ratio and particle mass fraction on the storage stability of emulsions were studied through the single factor experiments.The optimal condition is that the mass fraction of hydrophobic silica is 4%,the oil-water volume ratio is 6∶4,the mass fraction of hydrophilic silica is 5%,and the water-W/O emulsion volume ratio is 8∶2.The effects of pH value and salinity on the stability of emulsions were also studied by measuring the zeta potential of the silica surface under different conditions.The results showed that salinity has a negative effect on the stability of W/O/W emulsions while W/O/W emulsions are stable when pH value is around 6.When pH value is over 7,the emulsification ability of silica is decreased,which is detrimental to the stability of emulsions.