Surfactant-stabilized foams have been at the centre of scientific research for over a century due to their ubiquitous applications in different industries. Many of these applications involve inorganic salts either due to their natural presence (e.g. use of seawater in froth floatation) or their addition (e.g. in cosmetics) to manipulate foam characteristics for the best outcomes. This paper provides a clear understanding of the effect of salts on surfactant-stabilized foams through a critical literature survey of this topic.

Available literature shows a double effect of salts (LiCl, NaCl and KCl) on foam characteristics in the presence of surfactants. To elucidate the underlying mechanisms of the stabilizing effect of salts on foams, the effect of salts on surfactant-free thin liquid films is first discussed, followed by a discussion on the effect of salts on surfactant-stabilized foams with the focus on anionic surfactants. We discuss two distinctive salt concentrations, salt transition concentration in surfactant-free solutions and salt critical concentration in surfactant-laden systems to explain their effects. Using the available data in literature supported by dedicated experiments, we demonstrate the destabilizing effect of salts on foams at and above their critical concentrations in the presence of anionic surfactants. This effect is attributed to retarding the adsorption of the surfactant molecules at the interface due to the formation of nano and micro-scale aggregates.

一个多世纪以来，表面活性剂稳定泡沫一直是科学研究的中心，因为它们在不同行业中无处不在。由于无机盐的天然存在（例如在泡沫浮选中使用海水）或添加无机盐（例如在化妆品中）以控制泡沫特性以获得最佳结果，因此这些应用中的许多应用都涉及无机盐。本文通过对该主题的重要文献调查，清楚地了解盐对表面活性剂稳定泡沫的影响。

现有文献表明，在表面活性剂存在的情况下，盐类（LiCl、NaCl 和 KCl）对泡沫特性有双重影响。为了阐明盐对泡沫稳定作用的潜在机制，首先讨论了盐对不含表面活性剂的薄液膜的影响，然后讨论了盐对表面活性剂稳定泡沫的影响，重点是阴离子表面活性剂。我们讨论了两种不同的盐浓度，无表面活性剂溶液中的盐转变浓度和含有表面活性剂的系统中的盐临界浓度，以解释它们的影响。使用由专门实验支持的文献中的可用数据，我们证明了在阴离子表面活性剂存在的情况下，盐对处于或高于其临界浓度的泡沫的不稳定影响。