Gas flotation is an efficient technique used in the petroleum industry to remove oil contamination from produced water. This method is based on attaching air bubbles to oil droplets to make oil droplets rise faster. We investigated the role of water salinity in the efficiency of the process, using a model flotation column. We show that flotation efficiency increases with water salinity, highlighting the importance of the electrostatic repulsion between oil drops and air bubbles. We also studied the attachment between drops and bubbles, monitoring the temporal evolution of the thin films between them. Stable attachment requires that the water films formed between oil drops and air bubbles break and the oil spreads at the bubble surface. Increasing the salinity of the solution decreases the repulsion between the oil drops and the air bubbles, which in turn decreases the water film stability. The films rupture more readily, improving the drop–bubble attachment and thus the flotation efficiency. The differences in water salinity can therefore lead to important changes in the flotation efficiency.

中文翻译：

---

浮滴相互作用和盐分添加在浮选性能中的作用

气浮法是石油工业中用于从采出水中去除油污的一种有效技术。此方法基于将气泡附着在油滴上以使油滴上升更快。我们使用模型浮选柱研究了水盐度在过程效率中的作用。我们显示出浮选效率随水盐度的增加而增加，突显了油滴和气泡之间静电排斥的重要性。我们还研究了液滴和气泡之间的附着，监控了它们之间薄膜的时间演变。稳定的附着力要求在油滴和气泡之间形成的水膜破裂，并且油会在气泡表面扩散。增加溶液的盐度会减少油滴和气泡之间的排斥力，这反过来会降低水膜的稳定性。薄膜更容易破裂，从而改善了液滴的附着力，从而提高了浮选效率。因此，水盐度的差异可能导致浮选效率发生重大变化。