Research on the description and modification of the wetting phase during shape-selective agglomeration in suspensions.

• Applicant: Professor Dr.-Ing. Ulrich Bröckel
• Subject Area: Mechanical Process Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 467028815

Shape-selective agglomeration is a scientifically extremely exciting and forward-looking field of work. Due to shape-selective agglomeration it will be possible to carry out targeted separation not only according to the type of material, but also according to the particle shape. This possibility of processing can be applied in all technical processes in which the particle shape plays an essential role. In addition to the recycling of battery materials, further examples can be found in pigment production, the texture of food components or the bioavailability of pharmaceuticals. An essential basis is the understanding of interactions between suspended particles and binding liquid droplets during the wetting phase. The wetting phase is essential for the selectivity and efficiency of shape-selective agglomeration. In preliminary work, it was shown that the dynamic contact angle, static contact angle, and wetting kinetics can be accurately measured in the three-phase system. This methodology can now be used to quantify the influence of surfactants and changes in pH on the wetting phase. The issue of the interaction of particles and binder droplets in the suspension fluid will be investigated using a FluidFM based on AFM. An important indication of successful shape-selective agglomeration is the minimum torque curve measured for the first time at the end of the wetting phase. It is important to clarify which structural changes in the three-phase system lead to this minimum and the subsequent to an increase in torque. Whether the ratio of spherical to platelet-shaped particles in the micro-agglomerates changes around this minimum is essential for the basic understanding of shape-selective agglomeration.This leads to the following objectives:- Investigate the influence of particle size on shape-selective agglomeration.- Influence of surface modifications of the interacting partners by surfactants or pH changes on wetting properties.- Measurement of adhesion forces between particles and binding liquid droplets in the suspension liquid using a FluidFM.- Investigation of structural changes around the minimum in the torque at the end of the wetting phase.- Targeted increase of the shape-selective separation by optimal combination of parameters such as energy input, surfactant addition, pH value and/or monitoring of the torque.- Based on these findings, a first phenomenological description of the shape-selective agglomeration and its influencing parameters should be possible.

• DFG Programme: Research Grants