Abstracts of IGC Symposium 2018
IGC, a Tool to Assess the Influence of Processes on End-use Properties of a Solid
Dr. Rachel Calvet, Rapsodee, IMT Mines Albi, France
Divided solids are of great industrial interest, as 80% of industrial products or intermediates are powders. Various processes are implemented in industries for generating, handling and/or forming divided solids and can affect the surface properties of solids which can have an impact on the end-use properties of the solids. The first example deals with attapulgite milled in different conditions. Despite the high decrease in the particle size, the grinding stress slightly affected the parameters obtained by IGC until the fibrous structure is not affected. The effect of mechanical and chemical treatments upon lead adsorption properties of the attapulgite was also examined. A correlation was established between the IGC irreversibility index, obtained with isopropanol, a measurement of high energy sites, and adsorption capacity of lead in aqueous solutions.
In a second study, diatomaceous/TiO2 composites were elaborated by dry coating and used as photocatalysts in the degradation of bisphenol A. IGC measurements showed the modification of the surface properties of diatomaceous at infinite dilution and finite concentration with increasing amounts of TiO2. A relation between the adsorption capacity or the degradation rate of bisphenol A under the composite material and the irreversibility index was emphasized.
In both studies, IGC was of great interest to predict the influence of a surface modification by grinding or dry coating on adsorption capacity of an adsorbent towards a pollutant.
A Novel Approach for the Integral Thermodynamic Characterization of Materials via IGC
Costas Panayiotou, Department of Chemical Engineering, Aristotle University of Thessaloniki, Greece
Modern experimental setups of Inverse Gas Chromatography (IGC) provide with valuable information for the characterization of intermolecular interactions in a variety of materials. The key step in this characterization process is the use of the appropriate tools for the unbiased interpretation of the experimental IGC information. Over the recent few years an attempt was made to develop such a consistent thermodynamic approach with sound theoretical basis for handling IGC data. The first significant advantage of the new approach is its applicability to polar systems, especially, to systems interacting with strong specific forces (Lewis acid/base interactions or hydrogen-bonding). The method is relatively simple and may handle quite complex systems such as nylons, cellulose, (co)polymer mixtures, dyes, drugs, ionic liquids, and composite materials. The second advantage of the method arises from its sound theoretical basis and permits the direct exchange of IGC information with information from complementary experimental techniques including spectroscopy, interfacial/wetting studies, densitometry, etc. A number of examples of these applications will be presented along with the perspectives of the approach.
iGC-Characterization of Lignins as Bio-Based Precursors
for Sustainable Carbon Fibre Production
Peter Schiffels, Fraunhofer Institute for Manufacturing Technologies and Advanced Materials, Bremen (Germany)
The use of carbon fibre (CF) based composites is of growing importance in many industrial applications and novel processes are needed which can utilise sustainable precursor materials to produce carbon fibres of adequate quality. Lignin is the second most abundant bio-polymer which accounts for approximately 30% of the organically bound carbon, but it exhibits a heterogeneous composition and according to present knowledge lacks a defined primary structure. Blending of Lignins from waste streams with polymers to produce precursor fibres (PF) seems to be a promising route for a resource efficient and sustainable carbon fibre production, but extraction conditions and biological feedstock variability complicate the Lignin chemistry and thus the blend design. Blending is required to achieve a sufficient precursor fibre processability but the overall Lignin content strongly depends on the miscibility during the extrusion. In this talk, I present recent results for the characterization of Lignins originating from different feedstocks and extraction processes by means of the inverse Gas Chromatography (iGC) technique. Infinite dilution as well as low to medium surface coverage experiments are discussed and thoroughly analysed using a Python-based numerical analysis package developed by the author.
Inverse Gas Chromatography in Examination of Zeolites
Beata Strzemiecka, Mariusz Sandomierski, Małgorzata Kasperkowiak, Artur Jamrozik, Adam Voelkel, Poznan University of Technology, Faculty of Chemical Technology, Institute of Chemical Technology and Engineering, Poznan, Poland
Zeolites hold great promise in many applications mainly due to its non-toxicity, low price. They are applied in catalysis, separations, ion exchange industries, environmental remediation and in new functional materials field. Zeolites are also used as fillers in many other types of polymers due to their unique porous properties.
In all aforementioned applications the surface properties (e.g. ability to dispersive as well as specific interactions, activity, porosity) are of great importance. Most commercial technique for assessment of surface activity is nitrogen adsorption. However, this method is not sufficient for characterization of adsorbents and prediction of adsorption process course. Much deeper insight can be achieved by using IGC method. Studying of zeolites independently of used method is a great challenge, e. g. due to their very active surface which causes very strong adsorption of test solutes.
In this presentation the problems of accurate surface characterization of zeolites are discussed. Moreover, the possibilities of IGC technique in description of zeolites surface are presented as well as they are compared with other techniques applied for surface characterization. The utility of IGC technique in industry is strongly presented.
TiO2 Pigment Characterization by IGC – Influence of Sample Preparation and Experimental Setup
Sven Uwe Böhm, Thomas Koch, KRONOS INTERNATIONAL, Inc., Leverkusen, Germany
As producer of TiO2, the ultimate pigment white, since more than 100 years KRONOS has the need to characterize the properties of its pigments with high resolution. Especially nowadays, where pigment development is proceeding to optimal customer matrix adoption, there is a need for high resolution, high quality analysis methods that provide statistical average values for surface properties. IGC ID as well as IGC FC are both excellent methods for characterization particle surfaces.
In this content, we present a study on the influence of preparation parameters as well as differences in the experimental setup on the results of IGC measurements. IGC ID measurements with two different setups are compared, as well as the influence of changes in sample preparation on the results.
In addition to the fact that IGC is a reliable tool to characterize surface properties of TiO2 pigments, it can be seen that death volumes have critical influence on measurement results and that even a change in tempering time of the sample preparation has critical influence on the measurement results. Measurements of base materials, plastic pigment types and various coating pigments show a strong correlation between pigment properties and IGC results.
The development of carbon particles with defined surface structure supported by Inverse Gas Chromatography
M. Sattes, C. Damm, W. Peukert, Institute for Particle Technology (LFG), Erlangen, Germany
Due to a restricted amount of combustible materials and because of global warming alternative energy sources need to be found. Renewable energy sources are promising but are not available at all times to serve as reliable global energy suppliers. Thus, storing methods for energy need to be improved to overcome these fluctuations. A promising energy storing method is the production of hydrogen by water electrolysis via membrane-electrode-assemblies (MEAs).1 A need for further research in this area lies in studying the interactions between the different components present in an active catalyst layer, in particular the ionomer, the carbon black support particles and the platinum catalyst.
We could show by means of IGC studies that different batches of “identical” industrially available coated carbon materials vary strongly in their surface energy distribution. Thus the necessity of producing homogenous carbon particles with reproducible surface chemistry is a first step to optimize the functional layers of MEAs. To further study the influences of the carrier material on catalyst layer properties, we have started to develop methods to adjust the surface properties of carbon materials. To synthesize homogenous particles, we apply a hydrothermal approach to polymerize sugar particles. For characterizing the surface properties of the synthesized particles IGC is a valuable tool along with crystallinity and thermal stability investigations.2,3,4 Moreover, IGC and other particle characterization methods allow a direct comparison of the properties of the synthesized particles with industrially available materials. We could show that the particles obtained with a good reproducibility are spherical with a low amount of pores in the structure and with a high polar surface energy due to functional groups. As a consequence the heterogeneity of dispersive surface energy distribution is decreased compared to industrial materials. For a future application, we investigate thermal treatment and chemical surface modification to reduce the polar surface energy contribution by oxygen containing groups and enhance the dispersive surface energy. All these effects are investigated by IGC as well.
Characterizing complex surfaces of industrial relevance by inverse chromatography
Matthias Kellermeier, BASF SE, Material Physics, Ludwigshafen, Germany
Surfaces and interfaces are key to improve the performance of materials and systems in virtually any area of industrial application. Due to the complexity of real surfaces with regards to structure, chemistry and energetics, it remains challenging in many cases to grasp the relevant effects analytically in order to (ideally) explain observations made in actual application tests based on physical understanding. Thus, there is a persistent need for new experimental techniques that are able to provide an alternative, complementary and/or more precise view of the details of a given surface of interest. In this context, inverse chromatography (iC) methods have received increasing attention over the recent years, not least due to their ability to deliver a broad spectrum of accurate thermodynamic parameters for both solid/liquid (inverse liquid chromatography, iLC) and solid/gas (inverse gas chromatography, iGC) interfaces. Compared to other (more established) characterization techniques, iC methods further offer the advantage that materials with complex geometries such as powders, fibers or porous networks, can be investigated in a widely artifact-free manner. This presentation will give an overview on the use of iGC and iLC in BASF research and development. Several selected examples will be discussed to highlight the versatility of these techniques and their great (yet still by far not fully leveraged) potential in the characterization of complex surfaces across a broad range of industrial areas of application.