A Pickering emulsion is an emulsion stabilized by solid particles accumulated at the surface of droplets. It is also possible to create a stable Pickering emulsion stabilized by ferromagnetic iron oxide nanoparticles to make it susceptible to magnetic fields. This type of emulsion has received great research interest in recent years because it has generated and holds the promise of a variety of practical applications. One interesting application is magnetic separation in the gradient magnetic field. However, the real-time characterization of magnetic Pickering emulsions, especially under external stimuli such as magnetic fields, is generally challenging. We used a convenient method to control the properties of magnetic particle-stabilized emulsions via the ultrasound technique. In the experiments, we investigated the attenuation of ultrasound using ultrasonic spectroscopy as a function of the magnetic particle concentration and magnetic field intensity. The analysis of ultrasonic waves as a function of frequency provided information about the movement of magnetic Pickering droplets during magnetic separation. The results showed much weaker separation for a low magnetic particles concentration as the magnetic force was not sufficient to induce significant droplets movement, whereas for a high concentration the magnetic separation occurred very dynamically.

Pickering 乳液是一种通过液滴表面积累的固体颗粒稳定的乳液。还可以创建由铁磁性氧化铁纳米粒子稳定的稳定 Pickering 乳液，使其对磁场敏感。近年来，这种类型的乳液受到了极大的研究兴趣，因为它已经产生并具有多种实际应用的前景。一项有趣的应用是梯度磁场中的磁分离。然而，磁性 Pickering 乳液的实时表征，尤其是在磁场等外部刺激下，通常具有挑战性。我们使用一种方便的方法通过超声技术控制磁性粒子稳定乳液的性质。在实验中，我们使用超声波谱研究了超声波衰减与磁性粒子浓度和磁场强度的关系。超声波作为频率函数的分析提供了有关磁分离过程中磁性 Pickering 液滴运动的信息。结果表明，低磁性粒子浓度的分离弱得多，因为磁力不足以引起显着的液滴运动，而高浓度的磁性分离非常动态地发生。