Inverse gas chromatography studies of the esterification of glass particles with different morphologies

The separation of fine particles is a challenging task where a proper understanding of the interfacial properties is crucial. In our research, we focus on flotation, which is a powerful and widely used separation technique, where valuable mineral particles are selectively separated from unwanted gangue, with particles in the size range of about 10 µm to 200 µm. For this process, particle properties such as wettability, size or morphology are fundamental separation features.
Although, it is a well-established processing technique that is used all over the world in industry, there are still some challenges with regard to the processing of ultrafine particles with sizes below 10 µm. The aim of this project, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”, is to gain a deeper understanding of the microprocesses that occur during flotation and to have a closer look on the influence of particle properties, like wettability and morphology.
For this research glass particles are used as their surface chemistry can be modified in different ways. Here, the functionalisation was carried out by esterification with alcohols, where the wettability of the product can be controlled by the length of the alkyl chain. In order to investigate the effect of particle morphology on flotation three differently shaped glass particles were used and esterified, including fibres, spheres and fragments with differing shapes. Inverse gas chromatography is used to characterise the particles surface energy distributions, which provide information about the particles wettability as well as the heterogeneity of the surface.