Separation Sciences: Pioneering the Future of Materials Science

Materials science is at the heart of innovation in terms of industry and research, helping expedite advancements in materials characterization and analysis techniques and, more importantly, in the development of new materials.¹

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Industrialized societies rely heavily on advanced materials such as optical fibers, lightweight composites, and silicon microchips for use in a wide range of applications – however, a crucial aspect of achieving materials for these applications is the science of separation.

While materials scientists probe the properties of materials, process engineers are required to separate the various substances found in these materials for the purposes of quality control and production. Both the appropriate analytical tools and the application of high-throughput techniques are of the utmost importance to separation scientists, especially when it comes to producing high-quality, reliable outcomes.^2,3

As one of the main tracks at Pittcon, experts from around the globe will be coming together to review how advances in separation science can fuel developments in materials science.^4,5,6,7 Teams from the Universities of Iowa and Utah and from Thermo Fisher Scientific will also host talks on advanced chromatographic separation techniques based on Raman and infrared spectroscopy.

What is Separation Science?

As most compounds occur in nature as a mixture, chemists often need to separate substances prior to their application in production or research. They may also need to separate these substances for the purposes of quality control. In practice, separation science is not just one science but a combination of several sciences. The technical definition of separation is the division of a mixture into its constituent parts, each with distinct chemical properties.⁸

Separation occurs according to the mass, shape, density, size, volatility, solubility, charge, chemical affinity, or other properties of each substance. Depending on requirements, separations can also be performed consecutively for each of these properties. The list of separation techniques is extensive and includes filtration, distillation, centrifugation, and spectrometry.⁹

Applications of Separation Science

Separation science — also called chromatography because it was historically employed in the separation of colored compounds — is about selecting the right processes to achieve optimal results. With this in mind, scientists may separate compounds to varying degrees of purity. In fact, complete purity is not always required and must be balanced against production costs. Gold ore, for example, may be processed to varying degrees of purity. In analytical chromatography, relative amounts of constituent chemicals (analytes) are studied in small amounts of material. There is no requirement to prepare materials for use in production. In contrast, in preparative chromatography, mixtures are separated but also prepared for further processing at small or industrial scales.¹⁰

Advances in Separation Science

Separation processes can occur over various timescales, from molecular diffusion and adsorption, which occur in microseconds, to physical and structural morphosis, which requires several hours. Over these timescales, a degradation in separation capacity, selectivity, and throughput develops, yet their molecular basis is not understood. Therefore, understanding the physical and chemical processes underlying separation is essential to continuing development.¹¹

Exploring Separations at Pittcon

To that end, the annual Pittcon Conference and Exposition will be host to a symposium of experts in chemical separations that will explore future research directions in separation science. The symposium ‘Exploring Separations: Spectroscopy, Imaging and Therory’ will be organized by Max Lei Geng, professor of analytical chemistry at the University of Iowa.^4,12

Professor Lei Geng and his team have been investigating interfacial behaviors inside nanosized porous materials. They have found that dynamic adsorption, diffusion, and transport of molecules are influenced by physical and chemical properties in materials that can be fine-tuned according to pore size, structure, and surface characteristics. The symposium will also feature the following research directions:

• Joel Harris, a professor of chemistry at the University of Utah, has been focusing on the analytical spectroscopy of molecules at liquid-solid interfaces.
• Christy Landes, professor of physical chemistry at  Rice University, is developing new spectroscopic tools to study chemical dynamics at interfaces.
• J. Ilja Siepmann, professor of chemistry at the University of  Minnesota, has developed molecular models of interfacial chromatography processes.

Visualizing Changes with Multiscale Imaging

Professor Lei Geng and his team have also been investigating two-dimensional spectrally-resolved fluorescence correlation imaging for the detection of cancer.¹² This combines spectral and temporal data of tissue fluorescence resulting in high levels of contrast between samples.

As such, Professor Lei Geng will be presenting a talk on ‘Multiscale Imaging of Chromatography: Imaging Microsecond Diffusion and Adsorption to Visualizing Changes in the Chromatography System in Hours,’ which will highlight the use of multiscale imaging methods, operating from microsecond timescales up to several hours, to capture real-time images of molecular diffusion and adsorption rates inside stationary phase particles.⁵

Confocal Raman Spectroscopy

To develop stationary phase materials, Professor Harris needed to understand how interface structures could function as separation media. To achieve this, the team adapted confocal Raman microscopy to observe the interior surfaces of porous silica particles, thereby capturing structural information in real-time. This will form part of his presentation at Pittcon.⁶

By using Raman microscopy, the scientists could probe interfaces inside individual porous particles and extract quantitative information on molecule populations at interior surfaces. Measurements were effected in situ to allow observation as solute compositions varied. This marks the first use of confocal imaging to observe separation processes in real-time, thereby signaling an exciting new development in analytical chemistry.

Furthermore, Dr. Alexander Rzhevskii, Senior Application Scientist at Thermo Fisher Scientific, will be highlighting practical considerations in the application of Raman microscopy to the characterization of nanomaterials.⁷

It is also worth noting that infrared absorption spectroscopy is often used to detect vibrational modes in molecules. In fact, Raman spectroscopy is a complementary tool to infrared spectroscopy: Even though both methods can detect vibrational modes, they relay different types of information.¹³

Separation Science Drives Materials Science

Separation processes play an integral role in industry, especially considering the United Nations’ Sustainable Development Goals.¹⁴ The various methods developed in separation science have also contributed to innovations in other sciences like biology, chemistry, and materials science: Innovations such as DNA fingerprinting and ultra-trace residue analysis, for example, have been made possible thanks to advances in separation science.⁸

Membrane processes are also regarded as a key separation technology that will play a pivotal role in sustainable production. Materials science underpins innovation in membrane process technology and vice versa. In fact, membrane process technology requires the production of thin-layer materials. Polymers (which offer unique possibilities in cheap and scalable thin layer production) are the materials of choice in porous (e.g., ultrafiltration) and dense (e.g., gas separation) industrial membrane technologies.

Key Findings

Chemical separations underpin essential industries such as food production, energy, pharmaceuticals, chemicals, energy, and clean water. However, separations are not always understood or even considered during production. This leads to inefficient or adverse production processes. In its 2019 report, the National Academies of Sciences, Engineering, and Medicine in the United States has recommended research directions in separation science for a healthier and more sustainable future.¹⁵

As one of the main tracks at Pittcon, materials science continues to make an important contribution to separation sciences. Pittcon aims to foster collaboration, education, and innovation in materials science, separation science, food science, and many more. For more details on presentations, events, and how to register, please visit Pittcon’s website.

References and Further Reading

1.  Ayatullah Hosne Asif A. K., et. al.  (2020) A Brief Overview of Different Analytical Techniques for Material and Chemical Analysis. Int. J. Instrum. Sci., 7(1), pp. 1–12. http://article.sapub.org/10.5923.j.instrument.20200701.01.html
2. Vervoort N., et. al. (2021) Recent Advances in Analytical Techniques for High Throughput Experimentation. Anal. Sci. Adv., 2(3–4), pp. 109–127. https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/ansa.202000155
3.  Pino, V. (2021) Living in a Material World. [online] Available at: https://theanalyticalscientist.com/techniques-tools/living-in-a-material-world
4.  Pittcon. Exploring Separations: Spectroscopy, Imaging and Theory. [online] Available at: https://pittcon.secure-platform.com/2023/solicitations/1/sessiongallery/37
5.  Pittcon. Multiscale Imaging of Chromatography: Imaging Microsecond Diffusion and Adsorption to Visualizing Changes in the Chromatography System in Hours. [online] Available: https://pittcon.secure-platform.com/2023/solicitations/1/sessiongallery/schedule/items/37/application/2019
6.  Pittcon. Confocal Raman Microscopy for Probing the Interior of Individual Chromatographic Silica Particles to Interrogate Interfacial Structure and Function. [online] Available: https://pittcon.secure-platform.com/2023/solicitations/1/sessiongallery/schedule/items/37/application/1408
7.  Pittcon. Modern Raman Microscopy and Imaging for Applications in Nanotechnology and Material Science. [online] Available: https://pittcon.secure-platform.com/2023/solicitations/1/sessiongallery/43
8.  Chromatography Today. (2014) What is Separation Science? [online] Available at: https://www.chromatographytoday.com/news/gc-mdgc/32/breaking-news/what-is-separation-science/30752
9.  Harvey, D. (2020) Classifying Separation Techniques. Chemistry LibreTexts. [online] Available at: https://chem.libretexts.org/Courses/BethuneCookman_University/B-CU%3A_CH-345_Quantitative_Analysis/Book%3A_Analytical_Chemistry_2.1_(Harvey)/07%3A_Obtaining_and_Preparing_Samples_for_Analysis/7.06%3A_Classifying_Separation_Techniques
10.  LUT University. Separation Science. [online] Available at: https://www.lut.fi/en/about-lut/faculties/lut-school-engineering-science/separation-science
11.  Elsevier. Separation Science and Technology. [online] Available at: https://www.elsevier.com/books-and-journals/book-series/separation-science-and-technology
12.  M Lei Geng. University of Iowa. [online] Available: https://chem.uiowa.edu/people/m-lei-geng
13.  Le Pevelen, D.D. (2017) NIR FT-Raman. In Encyclopedia of Spectroscopy and Spectrometry, Elsevier. pp. 98–109. https://www.sciencedirect.com/science/article/pii/B978012409547212150X
14.  Frontiers. Future Perspectives on Separation Technologies. [online] Available at: https://www.frontiersin.org/research-topics/31403/future-perspectives-on-separation-technologies
15.  National Academies. (2019) New Report: A Research Agenda for Transforming Separation Science. [online] Available at: https://www.nationalacademies.org/news/2019/06/a-research-agenda-for-transforming-separation-science

This information has been sourced, reviewed and adapted from materials provided by Pittcon.

For more information on this source, please visit Pittcon.