A Research Agenda for Transforming Separation Science (2019) / Chapter Skim
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5 A Research Agenda: A Vision for the Future of Separation Science
5 A Research Agenda: A Vision for the Future of Separation Science
Pages 48-75
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From page 48... ...
The fies its highest-priority research directions categorized in ability to make molecules and assemblies of molecules two fundamental research themes: designing separations that have the desired functional properties is necessary that have high capacity, selectivity, and throughput; and to advance separation science. However, there are synunderstanding temporal changes that occur in separation thesis challenges with making new materials in a form systems.
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From page 49... ...
Overdardized systems of materials and testing protocols for all, the current fundamental knowledge on how matter separation science and the exploitation of data science to interacts in complex environments, including the static extract new knowledge and insights from large complex and dynamic properties of interfaces, is insufficient to dedatasets. Those two cross-cutting topics are discussed af- sign and manufacture highly selective, high-capacity, and ter the eight research directions.
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From page 50... ...
Numerous ond, scientists must be able to design separation materials potential separation materials need to be studied, but the for mixtures that contain species of vastly different con- number of materials already being considered precludes centrations. Third, improvements in the limits of detec- the study of materials for multicomponent systems, which tion continue to push the requirements for trace analysis.
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From page 51... ...
To improve selectivity, capacity, or throughput in Separation science combined with sensitive detec- separation processes, separation scientists could explore a tion methods, such as mass spectrometry, is an essential broader range of multiple forces, entropic strategies, and tool for understanding the world. As an example, precon- cooperative binding mechanisms; a wider array of chemi
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From page 52... ...
ration, solvent prestructuring into biphasic or multiscale Separation scientists can tune the free energy of the sys- architectures has recently been implicated as influentem by using a multitude of forces -- such as dispersion or tial in both selectivity and capacity (Kunz et al., 2012; van der Waals forces, dipolar forces, dipole-induced di- Ellis et al., 2014; Poirot et al., 2016; Duhamet et al., 2017; pole forces, hydrogen bonding, hydrophobic interactions, Ballesteros-Gomez et al., 2018; Karmakar et al., 2018)
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From page 53... ...
Biological systems are often required to select a (Anderson et al., 2002) and the application of the multiple targeted species from chemically similar constituents in BOX 5-1 Crystal Engineering Approaches to Chemical Separations Scientists are getting better at predicting phase diagrams from thermodynamic data, but can we design entirely new crystalline phases that lead to crystallization of target species?
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From page 54... ...
The development of experimental methods for mea- Research and development in those fields is needed so suring the many potential forces between species and that modeling and simulation can be used more effecseparation materials directly can greatly facilitate prog- tively to explore the free-energy landscape of separation ress. The techniques include use of a surface-forces appa- processes.
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From page 55... ...
Other triggers have recently started to be or materials provide enhanced selectivity, the removal of used for the cycling of separation materials, as described endogenous interferences, or the improvement of isomer in Chapter 3, including light, electric and magnetic fields, separations. One example of a successful chemical transand microwaves (Li and Hill, 2017; Mao et al., 2018)
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From page 56... ...
with such reactants as piperazine, a cyclic amine that when mixed with MDEA increases reaction rates with CO2 and increases the capacity for CO2 capture with lower corrosion, vapor pressure, and energy use. A large array of alternative chemical transformations are also under consideration, such as solvating CO2 in an ionic liquid (see Box 5-2)
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From page 57... ...
When Understand the Interfacial Forces interfaces do influence a separation system, it might be possible to design the interfaces to accomplish particular In separation processes, selective mass transfer often separation tasks, ranging from kinetic resolution of the occurs across interfacial regions -- the external interfaces main mixture components to selective exclusion of conof porous solids rather than the extended internal spaces. taminants or foulants that can compromise the robustness Although the structure and dynamics of such external in- of the separation process (see Theme 2)
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From page 58... ...
Of particular interest are twoenvironments that include heterogeneous sites or defects, dimensional porous materials in which the internal and which could affect separation outcomes. The latter inter- external interfacial fractions are similar and in nanometerfaces, unavailable to nonporous surfaces, can also exhibit scale proximity to one another, maximizing the potential confinement effects.
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From page 59... ...
Functionalized sur- forces at interfaces is critical for improving the perforfaces that have hydrophilic or polar molecules can have mance of capillary electrophoresis, chromatography, a substantial effect on selectivity and capacity because of membrane filtration, adsorption, ion exchange, affinity solute adhesion and surface charge of the solid surfaces multimodal systems, and others. For example, the behav(beads, membranes and microfluidic channels)
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From page 60... ...
Alternatively, one might level to separate small molecules -- such as nitrogen, oxybe able, de novo, to design separation materials that can gen, CO2, and methane -- remains challenging in a variety harness the effects of system components and conditions of separation systems. To take advantage of the influence to limit adverse effects of interfaces on separation kinet- of external stimuli (such as mechanical responses)
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RESEARCH DIRECTIONS 2-A. Determine changes from nonequilibrium states that affect the chemical and physical properties of separation materials.
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, the polymer structure relaxes, thereby changing the separation capabilities, often in an unpredictable fashion. A molecular-level picture of the changing physical nature of these nonequilibrium states would help to deter mine how separations occur when exposed to nonequilibrium separation materials.
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The Separation Materials and How the Reactions Are changes can be ascribed to solid-state crystalline-phase Influenced by Operating Conditions transitions, the breaking of chemical bonds, or the structural collapse of pores. The specific pathways to forma- In many cases, degradation of separation systems oction of new metastable states can be related to a variety of curs via chemical reactions (hydrolysis, radiolysis, oxifactors, such as the chemical composition of the porous dation, thermal decomposition, oligomerization, depolymaterial, removal of adsorbed molecules (such as water or merization, and so on)
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From page 64... ...
Such processes lead to substantial losses in ZIF-8 crystallinity and internal surface area and thereby decrease separation performance compared with the pristine ZIF sample. Fundamental studies on bond stability under various complex testing conditions are necessary to determine the applicability of these materials in real separations.
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From page 65... ...
Therefore, both the dethe previous paragraph. Those systems should be chosen tailed chemistry of the various degradation reactions and to have well-characterized separation materials (for ex- their interactions with separation materials and the relample, a solid aluminosilicate adsorbent or a relatively evant phase equilibria must be understood.
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From page 66... ...
The studies described above -- of suppressed; these cases could then be analyzed quantita- changes in separation materials as a function of time (for tively. Rate-accelerated testing that can elucidate material example, rates of change from nonequilibrium states, reevolution under separation conditions could be developed action chemistry and kinetics, and precipitation and agon the basis of quantitative models.
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From page 67... ...
separation agents that impart an unintended selectivity to Another strategy to address changes in a separation the system. material is to design separation materials to be self-heal Although degradation has typically been an after- ing.
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From page 68... ...
The International Association of Chemical Ther modynamics and the International Union of Pure and For a variety of separation processes -- such as ab- Applied Chemistry led a round-robin project in which sorption, adsorption, and membrane-based separations -- researchers around the world made high-quality reference an ever-increasing number of new separation materials measurements on the thermodynamic and thermophysical are being developed. Many are designed, synthesized, properties of the same sample (purity verified by NIST)
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From page 69... ...
ments have been used in interlaboratory studies of the The efforts described above to develop standard sys- ZSM-5 adsorption of CO2 described earlier (Nguyen et tems and samples for separation materials are excellent al., 2018)
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From page 70... ...
It is rarely sufficient, however, to describe separato develop predictive models to advance the design of tion processes solely on the scales accessible with those separation materials and systems. Computational meth- methods; it is necessary to incorporate methods that acods should ultimately allow the tailoring of materials for count for long-range forces, such as dispersion and solvatargeted separations with desired performance and the tion forces.
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From page 71... ...
stitute an ideal framework within which to study how energy is partitioned within multifaceted, hierarchical Recommendation: The research community should use structures. data science, modeling, and simulation with experimental measurements to develop a fundamental understanding Data Science of separation materials in complex environments and on multiple scales.
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From page 72... ...
2016. matography-mass spectrometry and solid-phase mi Phosphate ions affect the water structure at functional- croextraction with on-fiber derivatization.
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From page 73... ...
: An inorganic mimic fusion in Nanoporous Materials. Weinheim, Germany: of cyclodextrins.
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From page 74... ...
West. Analytical and Bioanalytical Chemistry 410(7)
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From page 75... ...
for phosphonium-based ionic liquids with 2-cyanopyrro- Tiwari, R
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