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Ion Exchange in Purification
Published in Juan A. Asenjo, Separation Processes in Biotechnology, 2020
Displacement chromatography has two major advantages over isocratic elution chromatography: (1) it permits loading of more feed material, and (2) the product concentrations are much higher. Therefore, displacement chromatography has a high potential for large-scale separations of biochemicals (Frenz and Horváth, 1985). It is not yet widely used in large-scale separations because of the following common problems: (1) suitable presaturant and displacer for a given feed mixture are often unavailable; (2) column regeneration time is usually long, because it involves the displacement of the most preferred species (displacer) by the least preferred species (presaturant); and (3) biochemicals themselves are buffers, and their affinities are highly dependent on pH. Therefore, controlling the pH during the displacement process can be difficult.
Process Design Considerations for Large–Scale Chromatography of Biomolecules
Published in Kenneth E. Avis, Vincent L. Wu, Biotechnology and Biopharmaceutical Manufacturing, Processing, and Preservation, 2020
Richard Wisniewski, Egisto Boschetti, Alois Jungbauer
In displacement chromatography the mixture, including the product of interest, is loaded onto the column and displacer, with high affinity to the media, displaces the adsorbed molecules on the principle of competitive adsorption/desorption. Due to differences between these competitive processes for various molecules in the initial mixture, the desorbed substances form bands moving in the form of a chain through the column. The bands of pure substances move along the column, with speed controlled by the movement of the displacer. Displacement chromatography is rarely used in large-scale industrial operations. Problems exist with the selection of displaces, and the simple UV detection technique may not be sufficient due to partial overlap of the elution bands (Freitag and Breier 1995). A fast analytical HPLC instrument may be used to monitor the bands.
Downstream Processing
Published in Debabrata Das, Soumya Pandit, Industrial Biotechnology, 2021
Chromatography separates mixtures into components by passing through a bed of adsorbent material over a fluid mixture. In elution chromatography, a column is packed with adsorbent particles that can be solid, porous, gel, or liquid phase that is immobilized in or on a solid. A mobile process or fluid layer is filled with a combination of solutes. A liquid or eluent follows on from this wave. The pulse reaches a small condensed point but the extra solvent disperses and dilutes the exits. Specific solutes in the mixture interact differently with the stationary phase adsorbent material; some interact weakly with each other and some interact intensely. During chromatography, two or more solutes move to different levels of solids because of the diverse solubility of the solutes in a particular solvent. A mixture of solutes and a solvent are applied from one solid phase stage. Displacement chromatography can be attractive when processing large amounts of material. In this process the column undergoes sequential phase adjustments in inlet conditions (e.g. fluid nature). In this process is added the feed combination, accompanied by a continuous displacer fluid infusion. For the stationary phase the displacer has to have a higher affinity than any compound in the feed solution. The ‘drive’ displacer eliminates the stationary process and back into the active zone. Fermentation substances are segregated as follows by either of the chromatographic techniques below, in which isolation of the solutes occurs for the purposes mentioned. When conditions are correctly chosen, the feed components are pushed into neighbouring square wave-like zones of condensed, pure solutes. Such areas then split through the end of the column with the region having first left the solute with the lowest propensity for the stationary process. The primary benefit of displacement chromatography over elution chromatography is the capacity for better efficiency, but the process is more complex, and in certain cases high precision (separation of solutes) may be hard to achieve (Freitag, 2014).
Lithium Isotope Enrichment Effects in Liquid Metal/Chloride Molten Salt System
Published in Fusion Science and Technology, 2023
Ryo Ito, Fu Nomoto, Yasuyuki Ogino, Keisuke Mukai, Juro Yagi
The natural abundance of lithium is only 7.59% for 6Li, and 90% enrichment is required for fusion reactors.[2] Various methods of 6Li enrichment have been investigated, such as chemical exchange systems,[3,4] displacement chromatography,[5] ion exchanger,[6] intercalation,[7] electrophoreses,[8] electrodialysis,[9] laser-based separation,[10] and so on. The classical column exchange (COLEX) process using a lithium amalgam and lithium hydroxide solution, operated at the pilot plant at Oak Ridge National Laboratory between 1955 and 1963,[11] is the most technically and economically feasible method.[12] However, mercury has a negative impact on the environment, and in fact, mercury environmental contamination at COLEX plants has been reported.[11] It is desirable to establish an alternative method for 6Li enrichment.
Searching for optimal accident tolerant fuel for the VVER-1200 reactor from the neutronic point of view
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
A. Abdelghafar Galahom, Ehab M. Aboelyazid, S.A. EL-Fiki, Moustafa Aziz
In this type of reactor, we conducted some research in which we dealt with different types of fuel and different designs of fuel assemblies to reach the optimal fuel and design from the safety and economics point of view (Galahom 2017, 2018, 2019, 2020). In this work, different fuel types are investigated to reach the optimum ATF. Table 2 presents the characteristics of the proposed fuel to study in the VVER-1200 assembly. The standard fuel (UO2), uranium carbide (U12C), and the UN-based fuels are investigated in a separate fuel cycle. The production of separate isotope 15N has been costly in the past but recently using the Displacement Chromatography using CATION-Exchange resins shows promise that it can be done on a large scale (Ding et al. 2008).
Simulation and Optimization of Hydrogen Displacement Adsorption Process for Hydrogen Isotope Enrichment/Separation
Published in Fusion Science and Technology, 2018
Qiang-Hua Lei, De-Li Luo, Huan Wang, Yi-Fu Xiong, Guang-Hui Zhang, Wen-Qing Wu
Waste tritium recovered from various tritium treatment processes is stored as tritiated water in many cases, where a problem of accumulating storage inventory is coming to the fore. The waste management dealing with this problem requires some effective and economical methods for hydrogen isotope enrichment (or separation). Since cryogenic distillation is usually applied to large-scale cases and its structure and process are quite complex,1 a more convenient and simpler process would be requested for volume reduction of the tritiated waste storage managed in tritium-handling laboratories or facilities.2 For this application, a process based on the principle of displacement adsorption may be the most suitable candidate.3 Among various processes based on displacement chromatography, such as hydrogen displacement adsorption chromatography, frontal chromatography, and self-displacement chromatography, a hydrogen displacement adsorption process is a promising candidate because a higher recovery ratio (RR) and enrichment factor (EF) can be realized if proper separation materials are used.4,5