查看更多>>摘要：In the modeling of a simulated moving bed, several assumptions are considered, the key assumption is there are no radial concentration gradients based on perfect mixing. However, it is difficult to achieve perfect mixing because the injected flowrate of the bed is periodically changed in the process. In this study, the performance of the simulated moving bed process was analyzed when the injected flow such as the feed or desorbent stream was unevenly distributed. To this end, the distribution function of the injected flow was calculated and applied to the model. Two types of distribution functions were obtained using the experimental results of a previous study, and the simulation results were compared with classical modeling assuming perfect mixing. In the base case simulation, the purity was similar in all cases, the productivity was higher more than 5% in the even distribution case compared to the most uneven distribution case. The effect of distribution was analyzed through sensitivity analysis by changing the overall flow rate, switching time, bed length, and flow rate of sections 2 and 3. As a result, regardless of the distribution applied, the trends of the performance parameters were the same. However, the more uneven the distribution, the greater the difference in productivity, recovery, and desorbent consumption compared to the even distribution case. It was confirmed that the design that distributes the injected flow more evenly has a better performance. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Polystyrene (PS) microsphere is a kind of attractive extracting medium due to its high stability in different matrices and its particle size can be controlled. The attachment of amphiphilic copolymers to the PS microsphere surface can overcome the drawback of PS relevant to its hydrophobic nature and low wettability. In our previous work, the magnetic composite based on PS microsphere (5 mu m) and poly (divinylbenzene-co-N-vinylpyrrolidone, DVB-co-NVP) shell was successfully fabricated and applied for the extraction of safrole in cola drinks. However, the large size and ease of sedimentation limited its application in the enrichment of safrole from blood samples. Considering the adjustability of PS microsphere size, we synthesized the porous PS microspheres with the uniform size of 3 mu m and then functionalized with Fe3O4 nanoparticles and poly (DVB-co-NVP) layer in this work. Using the proposed material as extraction sorbent, a simple and fast magnetic solid phase extraction (MSPE) method coupled with HPLC was developed for quantification of safrole in the plasma. Under the optimized conditions, the response to safrole was linear in the range of 0.02-12 mu g mL(-1) , and the limit of detection (LOD) was 0.006 mu g mL(-1). Satisfactory recoveries were obtained between 85.67% and 97.74% (spiked at 0.05, 0.2, 2 mu g mL(-1)) and the relative standard deviations (RSDs) for the above spiked levels of the analyte were below 3.9% (n = 6). The adsorbent can be reused for 6 cycles without a significant loss of extraction capability. (C) 2021 Elsevier B.V. All rights reserved.
Jameson, John-KristianCosta, ThalesEijsink, Vincent G. H.Arntzen, Magnus O....
11页
查看更多>>摘要：Research on oligosaccharides, including the complicated product mixtures generated by lytic polysaccharide monooxygenases (LPMOs), is growing at a rapid pace. LPMOs are gaining major interest, and the ability to efficiently and accurately separate and quantify their native and oxidized products chromatographically is essential in furthering our understanding of these oxidative enzymes. Here we present a novel set of methods based on dual electrolytic eluent generation, where the conventional sodium acetate/sodium hydroxide (NaOAc/NaOH) eluents in high-performance anion-exchange chromatography (HPAEC) are replaced by electrolytically-generated potassium methane sulfonate/potassium hydroxide (KMSA/KOH). The new methods separate all compounds of interest within 24-45 min and with high sensitivity; limits of detection and quantification were in the range of 0.0 0 01-0.0 032 mM and 0.0 0 02-0.0 096 mM, respectively. In addition, an average of 3.5 times improvement in analytical CV was obtained. This chromatographic platform overcomes drawbacks associated with manual preparation of eluents and offers sim plified operation and rapid method optimization, with increased precision for less abundant LPMO-derived products. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
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Elsevier