On the importance of osmotic interaction during precipitation crystallization

在毫秒和秒范围内的加工时间内形成精细的、微溶的结晶相的结晶过程被称为沉淀结晶过程。由于沉淀产物的低溶解度，只有在高过饱和度下进行该方法，才有可能进行经济生产。在这样的条件下，固体形成过程如成核和生长以非常高的速率进行。颗粒形成机制的关键步骤必须清楚，以便能够预测最终的颗粒特性（粒度分布，形态等）。可通过沉淀获得的典型粒度为20 nm至10微米。因此，在足够高的过饱和水平下，固体沉淀是用于生产纳米颗粒的方法之一。这些颗粒可以通过一系列的二次过程，如团聚，重结晶和老化，这可以显着影响最终获得的沉淀物的性质，本研究的目的是澄清的假设，在颗粒生长过程中渗透相互作用是重要的初级粒子的聚集。初步估计，这种吸引相互作用的特点是相对较强和短距离。在文献中，渗透相互作用及其对沉淀过程中颗粒形成的影响尚未报道。同步辐射X射线衍射是研究这种效应的一种很有前途的实验方法。结合其他实验方法的X射线衍射测量应采用适当的建模方法进行解释。为此，现有的在线X射线衍射方法的沉淀过程的调查，必须超越其目前的状态。调查的重点是在沉淀过程中的颗粒形成的时间分辨观测和他们的解释相对于渗透相互作用的定性和定量的理解。

Crystallization processes which form a fine, sparingly soluble, crystalline phase at process times which are in the range of milliseconds and seconds are called precipitation crystallization processes. Due to the low solubility of the precipitated products economic production is only possible, if the process is performed at high supersaturation. Under such conditions, solid formation processes as nucleation and growth run very high rates. Crucial steps of the particle formation mechanism must be clear for being able to make predictions about the final particle properties (particle size distribution, morphology, etc.). Typical particle sizes that can be obtained by precipitation, are between 20 nm and 10 microns. Thus, at sufficiently high supersaturation levels precipitation of solids is one of the methods for producing nanoparticles. These particles can pass through a series of secondary processes such as agglomeration, recrystallization and aging, which can significantly affect the properties of the finally obtained precipitate.The aim of this research proposal is to clarify the hypothesis that during particle growth osmotic interaction is of importance for aggregation of primary particles. Preliminary estimation characterizes this attractive interaction to be comparatively strong and of short-range. In literature the osmotic interaction and its influence on particle formation during the precipitation has not yet been reported. In-line X-ray diffraction with synchrotron radiation is a promising experimental method for investigating this effect. X-ray diffraction measurements combined with other experimental methods shall be interpreted with appropriate modeling approaches. To this end the existing in-line X-ray diffraction method for the investigation of precipitation processes has to be developed beyond its current status. The focus of the investigation is on the time-resolved observation of particle formation during precipitation processes and their interpretation with respect to the a qualitative and quantitative understanding of the osmotic interaction.