Thermospectroscopic infrared imaging of a confined drying process

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-01, Vol.403, p.126167, Article 126167
• Main Authors: Lehtihet, M., Abisset, E., Chevalier, S., Sommier, A., Pradere, C., Leng, J.
• Format: Article
• Language: English
• Subjects: Confined drying; Engineering Sciences; Infrared imaging; Silica dispersion; Thermospectroscopy; Transport properties
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.126167

•InfraRed imaging technique for compositional and thermal mapping of transient systems.•Application to a drying droplet of silica dispersion confined between two hydrophobic substrates.•Colloids redistribution due to inhomogeneous drying is highlighted and accurately described.•A numerical statistical inverse method is used to retrieve mutual diffusion coefficient as transient maps. We present an infrared (IR) imaging technique that allows us to retrieve quantitative concentration and thermal maps with relatively fast acquisition times for samples that are evolving in time and have micron-scale spatial resolution. As a proof-of-concept, we image the transient drying kinetics of a μL drop of colloidal suspension in a confined geometry. Quantitative concentration maps inside the drying droplet are retrieved. Transport phenomena such as colloid redistribution inside the droplet due to inhomogeneous drying can be highlighted by this means. A numerical inverse method based on the acquired images that allows one to estimate intrinsic properties of the studied material, such as the collective diffusion coefficient of the mixture, is presented. Such a technique combined with statistical inverse methods provides a useful, non-invasive means of visualizing and estimating parameters of materials evolving in time.