BASF is using more and more Inverse Gas Chromatography (IGC) to characterize surface properties of particles of batteries, catalysts, building materials and many others. “IGC as a one-fits-all technique gives great – but hardly explored – details” Dr. Matthias Kellermeier, BASF, Material Physics, Ludwigshafen, Germany, summarized it perfectly during his talk “Characterizing complex surfaces of industrial relevance by inverse chromatography”.
Ten speakers from industry and academia exchanged their experiences with IGC during the 7th International IGC Symposium, 19.06.2018 in Cologne – with participants from 8 countries. The basic principle is quite easy: “15-20 different gas probes are used like AFM-tips to explore the surface properties” Dr. Ralf Dümpelmann, Inolytix AG, Switzerland, explained. “Many polar, apolar, cyclic and branched molecules are used to provide surface energies, nanoroughness, polarities and electron donor and acceptor properties”. Picture: Steven Abbott with results of the discussion group.
Practices & applications of IGC
However, the practices itself and the applications are very different, as the presentations showed. Dr. Peter Schiffels, Fraunhofer Inst. Bremen, showed the different surface qualities of lignin intended as precursor for bio-based carbon fiber production. Another practice was a good differentiation of industrial TiO2 samples shown by Sven Böhm, Kronos International, Leverkusen. In addition, the effect of different mills and grinding conditions on the mineral attapulgite was explained by Rachel Calvet, Ecoles des Mines, Albi, France. Other speakers provided examples about carbon black particles and zeolites.
Current limitations of IGC
The principles of IGC as such are very useful, but often there seemed to be limitations in terms of instrumental setup (concentration range, non-symmetric peaks, number of probes) and also controversial methodologies (“nominal” surface coverage treated as “real”, no operation under “ideal diluted” conditions). As a result, the true potential of IGC often seems not fully explored – with BASF as a positive exception, as mentioned above.
A new, automated and flexible setup
Therefore, Dr, Eric Brendle, Adscientis SARL, France, complemented this challenge by explaining not only the requirements of an ideal setup but also the advances towards an automated and fully flexible IGC. Controlled and highly accurate syringes for the injection of gases and liquids provide not only “ideally diluted” conditions, but also exact p/p0 settings for desorption isotherms. Altogether an excellent step towards reliable, industrial applications.
Finally, an interactive session and wrap-up presentations provided everyone a great picture of all the experiences, some limitations and many opportunities. Looking forward to see you next year in June... exact date and location to be announced!