selective liquid-liquid phase transfer

该方案的目标是在液-液界面多维分离亚微米颗粒(&lt；500 nm)。分离的多维方面是指(1)特定材料的分离和(2)特定尺寸的分离。特定材料的分离是通过目标粒子的选择性疏水来实现的。这种疏水作用依赖于静电驱动的离子表面活性剂的吸附，这将通过使用可水解的金属阳离子作为表面和表面活性剂之间的连接剂来辅助。这种吸附路线具有材料专一性的优点，即它创建了分离标准，并且是可逆的。特别是后一点非常重要，因为颗粒的疏水性可以通过水相中的pH变化来具体解决。颗粒在液-液界面上的稳定性主要取决于颗粒的大小。对于给定的润湿角和界面张力，大颗粒比小颗粒更有效地捕获在界面上。对于足够小的粒子，人们可以预料到完全的相变。这种转移发生的确切大小将取决于界面张力和润湿角。后两个量受表面活性剂的类型和浓度以及盐浓度的影响，这为调节分离提供了一种手段。多维分离的总体思想是使用定义明确的Pickering乳状液作为分离工具。连续相将是具有特定化学成分(pH、可水解盐、离子表面活性剂)的水悬浮液(尺寸范围为20-500 nm的SiO_2、Al_2O_3和/或TiO_2)。这用于实现目标颗粒的选择性疏水的目的。颗粒要转移到的油相将是长链正构烷烃。一旦水相和油相被乳化，预计小的目标颗粒将被转移到油相中，而较大的颗粒被困在水-油界面中。剩余相(S)的所有颗粒都将留在水相中。最终完成分离的基本步骤是从界面控制释放较大的颗粒。这将通过冻结乳化液的油相来实现。这一步骤将使小颗粒保持在固化油滴的内部，而大颗粒保持与水相接触。为了将这些颗粒转移回水相，将研究几种策略：油滴的表面熔化和涉及水化学调节的组合，以利用疏水作用的可逆性。对于不同的化学分离参数，整个过程将用多维分离函数进行量化。

The goal of the proposal is the multidimensional separation of submicron particles (< 500 nm) at liquid-liquid interfaces. The multidimensional aspect of the separation refers to (1) material-specific separation and (2) size-specific separation.The material-specific separation is achieved by selective hydrophobization of the target particles. This hydrophobization relies on the electrostatically driven adsorption of ionic surfactants, which will be assisted by the use of hydrolysable metal cations that act as linkers between the surfaces and the surfactant. This adsorption route has the advantage of being material specific, i. e. it creates a separation criterion, and it is reversible. Especially the latter point is of great importance, since the hydrophobicity of the particles can be addressed specifically by pH-changes in the aqueous phase. The stability of particles in liquid-liquid interfaces depends critically on the particle size. For a given wetting angle and interface tension, large particles are trapped more effectively in interfaces than small ones. For small enough particles one can expect that a complete phase transfer. The exact size at which this transfer occurs will depend on the interface tension and the wetting angle. The latter two quantities are influenced by the type and concentration of the surfactant as well as by the salt concentration, which offers a means to regulate the separation.The general idea for the multidimensional separation is to use a well-defined Pickering emulsion as a separation tool. The continuous phase will be an aqueous suspension (SiO2, Al2O3 and/or TiO2 in the size range of 20-500 nm) of defined chemical composition (pH, hydrolysable salt, ionic surfactant). This serves the purpose of achieving the selective hydrophobization of the target particles. The oil phase into which the particles are to be transferred will be a long-chained n-alkane. Once the aqueous and oily phase are emulsified, it is expected that small target particles will be transferred into the oily phase and larger particles are trapped in the aqueous-oil interface. All particles of the remaining phase(s) will remain in the aqueous phase. The essential step to finalize the separation is a controlled release of larger particles from the interface. This will be achieved by freezing the oily phase of the emulsion. This step will keep the small particles within the interior of the solidified oil drops while the larger particles remain in contact with the aqueous phase. Several strategies will be examined in order to transfer these particles back into the aqueous phase: Surface melting of the oil drops and a combination involving an adjustment of the aqueous chemistry in order to exploit the reversibility of the hydrophobization. The entire process will be quantified with multidimensional separation functions for different chemical separation parameters.