Process-technological fractionation of finest particles based on geometrical and material separation characteristics in a strong centrifugal field

作为优先项目“技术超细颗粒系统的高特异性多维分离”的一部分，该子项目研究了在半连续管式离心机的强离心场中利用几何和材料分离特性来分离纳米级颗粒集体。在第一个资助期，开发了一种方法，能够通过分析离心法和计算多维分级效率曲线来分析分离实验。颗粒的沉降系数取决于几何因素和材料因素，这与考虑流体动力直径不同，它包括几个维度。以重、轻纳米颗粒混合物的叠加尺寸和密度分级为例，说明了该方法的应用。实际确定分级效率曲线的困难在于为分布内的每个测量的分离标准分配相对数量或质量的颗粒。为了使用快速和非侵入性的测量方法，这一方面是借助UV-Vis光谱来实现的。该方法能够定量测定分馏颗粒混合物的组成。为了产生有价值的过程监控，采用了UV-VIS流量传感器。结果表明，在分级的情况下，可以在较长的处理时间内以较低的误差预测溢流中的颗粒浓度。在第二个资助期，重点将集中在通过离心机的分级效率曲线对过程分级进行实验评估。在此，悬浮性能和设备的操作条件等参数对分离结果具有决定性作用。另一个目标是根据多维分离特性对分离结果进行基于模型的评估和预测，误差尽可能小。同时，还可以得到所需分离结果的最佳操作参数选择。由于处理时间也影响管式离心机中悬浮液的半连续分馏，因此计划使用UV-Vis流量传感器实时监测分离动力学。因此，目的是记录稳定的测量信号，从该信号中可以提取关于细颗粒组分的相对颗粒浓度的信息。潜在地，可以通过调整操作条件来应对产品质量的负面变化。最终，该分项目正在对高性能离心机中的多维分离过程进行实验和基于模型的调查，制定解决方案战略，并更好地了解正在发生的物理过程。

As part of the priority program "Highly specific multidimensional fractionation of technical ultrafine particle systems", the subproject investigates the separation of nanoscale particle collectives using geometric and material separation characteristics in the strong centrifugal field of a semi-continuous tubular centrifuge. In the first funding period, a method was developed which enables the analysis of a separation experiment by means of analytical centrifugation and the calculation of multi-dimensional grade efficiency curves. The sedimentation coefficient of a particle depends on geometrical as well as material factors, which includes several dimensions in contrast to the consideration of a hydrodynamic diameter. The application of the method was demonstrated in the case of superimposed size and density fractionation of a particle mixture of heavy and light nanoparticles. The difficulty in the practical determination of a grade efficiency curve lies in assigning a relative number or mass of particles to each measured separation criteria within the distribution. With the aim of using fast and non-invasive measuring methods, this aspect was implemented with the aid of UV-VIS spectroscopy. The methodology enabled the quantitative determination of the composition of a fractionated particle mixture. In order to generate a valuable process monitoring, a UV-VIS flow sensor was incorporated. It was shown that in case of classification, a prediction of the particle concentration in the overflow can be made over a longer process time with low error.In the second funding period, the focus will lie on the experimental assessment of the process fractionation via grade efficiency curves of the centrifuge. Here, parameters such as the suspension properties and the operating conditions of the apparatus are decisive for the separation result. A further goal it to carrying out model-based evaluations and making predictions about the separation result, depending on the multidimensional separation characteristics, with as little error as possible. Simultaneously, the optimal choice of operating parameters for a desired separation result can be derived. Since the process time also influences the semi-continuous fractionation of the suspensions in a tubular centrifuge, real-time monitoring of the separation kinetics with the UV-VIS flow sensor is planned. The objective hereby is the recording of a stable measuring signal from which information about the relative particle concentration of the fine fraction can be extracted. Potentially, negative changes in product quality can be reacted to by adjusting the operating conditions. Ultimately, the subproject is working on the experimental and model-based investigation of multidimensional separation processes in high-performance centrifuges, on the development of solution strategies and on gaining a better understanding of the occurring physical processes.