Ion foam flotation of neodymium (Nd³⁺) was studied using a pH-sensitive surfactant, the nonaoxyethylene oleylether carboxilic acid, which has the peculiarity of remaining water soluble in the presence of multivalent cations. The flotation efficiency factors were determined as a function of pH and for two different (surfactant/Nd) molar ratios, equimolar (1/1) or stoichiometric (3/1). An opposite trend was observed, showing low (<30%) and high (>95%) ion extraction yields respectively for equimolar and stoichiometric conditions. We show that i) the determination of the surfactant/Nd speciation solutions is essential to understand the very different behaviors between equimolar and stoichiometric experiments and ii) the ion extraction process is mainly driven by interfacial mechanisms. In terms of applications we show that once the ion extraction is efficiently performed for pH values between 5 and 7, the recovery of the surfactant is possible by performing a second flotation process at lower pH (2.5). Moreover ion foam flotation using this pH sensitive surfactant was shown to be highly efficient for the removal of traces and ultra-traces of metal ions. Therefore the results presented here suggest that the development of a continuous process, for example in the context of waste water treatment, is feasible.

使用pH敏感型表面活性剂壬氧基乙烯油基醚羧酸对钕（Nd ³⁺）的离子泡沫浮选进行了研究，该表面活性剂在存在多价阳离子时具有残留的水溶性。确定浮选效率因子与pH的关系对于两种不同的（表面活性剂/ Nd）摩尔比，等摩尔（1/1）或化学计量（3/1）。观察到相反的趋势，分别显示在等摩尔和化学计量条件下离子提取率低（<30％）和高（> 95％）。我们表明，i）表面活性剂/ Nd形态溶液的确定对于理解等摩尔化学计量和化学计量的实验之间非常不同的行为是必不可少的，并且ii）离子萃取过程主要是由界面机制驱动的。在应用方面，我们表明，一旦在5至7之间的pH值下有效地进行了离子萃取，就可以通过在较低pH（2.5）下进行第二次浮选工艺来回收表面活性剂。此外，使用该pH进行离子泡沫浮选敏感的表面活性剂被证明对去除痕量和超痕量金属离子非常有效。因此，这里提出的结果表明，例如在废水处理的背景下，开发连续过程是可行的。