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Jatoi HUK, Goepel M, Poppitz D, Kohns R, Enke D, Hartmann M, Gläser R. Mass Transfer in Hierarchical Silica Monoliths Loaded With Pt in the Continuous-Flow Liquid-Phase Hydrogenation of p-Nitrophenol. FRONTIERS IN CHEMICAL ENGINEERING 2021. [DOI: 10.3389/fceng.2021.789416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Sol-gel-based silica monoliths with hierarchical mesopores/macropores are promising catalyst support and flow reactors. Here, we report the successful preparation of cylindrically shaped Pt-loaded silica monoliths (length: 2 cm, diameter: 0.5 cm) with a variable mean macropore width of 1, 6, 10, or 27 μm at a fixed mean mesopore width of 17 nm. The Pt-loaded monolithic catalysts were housed in a robust cladding made of borosilicate glass for use as a flow reactor. The monolithic reactors exhibit a permeability as high as 2 μm2 with a pressure drop below 9 bars over a flow rate range of 2–20 cm3 min−1 (solvent: water). The aqueous-phase hydrogenation of p-nitrophenol to p-aminophenol with NaBH4 as a reducing agent was used as a test reaction to study the influence of mass transfer on catalytic activity in continuous flow. No influence of flow rate on conversion at a fixed contact time of 2.6 s was observed for monolithic catalysts with mean macropore widths of 1, 10, or 27 µm. As opposed to earlier studies conducted at much lower flow velocities, this strongly indicates the absence of external mass-transfer limitations or stagnant layer formation in the macropores of the monolithic catalysts.
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Fujisawa K, Carvalho BR, Zhang T, Perea-López N, Lin Z, Carozo V, Ramos SLLM, Kahn E, Bolotsky A, Liu H, Elías AL, Terrones M. Quantification and Healing of Defects in Atomically Thin Molybdenum Disulfide: Beyond the Controlled Creation of Atomic Defects. ACS NANO 2021; 15:9658-9669. [PMID: 33754710 DOI: 10.1021/acsnano.0c10897] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Atomically thin 2D materials provide an opportunity to investigate the atomic-scale details of defects introduced by particle irradiation. Once the atomic configuration of defects and their spatial distribution are revealed, the details of the mesoscopic phenomena can be unveiled. In this work, we created atomically small defects by controlled irradiation of gallium ions with doses ranging from 4.94 × 1012 to 4.00 × 1014 ions/cm2 on monolayer molybdenum disulfide (MoS2) crystals. The optical signatures of defects, such as the evolution of defect-activated LA-bands and a broadening of the first-order (E' and A'1) modes, can be studied by Raman spectroscopy. High-resolution scanning transmission electron microscopy (HR-STEM) analysis revealed that most defects are vacancies of few-molybdenum atoms with surrounding sulfur atoms (VxMo+yS) at a low ion dose. When increasing the ion dose, the atomic vacancies merge and form nanometer-sized holes. Utilizing HR-STEM and image analysis, we propose the estimation of the finite crystal length (Lfc) via the careful quantification of 0D defects in 2D systems through the formula Lfc = 4.41/ηion, where ηion corresponds to the ion dose. Combining HR-STEM and Raman spectroscopy, the formula to calculate Lfc from Raman features, I(LA)/I(A'1) = 5.09/Lfc2, is obtained. We have also demonstrated an effective route to healing the ion irradiation-induced atomic vacancies by annealing defective MoS2 in a hydrogen disulfide (H2S) atmosphere. The H2S annealing improved the crystal quality of MoS2 with Lfc greater than the calculated size of the A exciton wave function, which leads to a partial recovery of the photoluminescence signal after its quenching by ion irradiation.
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Affiliation(s)
- Kazunori Fujisawa
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Research Initiative for Supra Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Bruno R Carvalho
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Departamento de Física, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil
| | - Tianyi Zhang
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Néstor Perea-López
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Zhong Lin
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Victor Carozo
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Physics, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 22451900, Brazil
| | - Sérgio L L M Ramos
- Centro de Tecnologia em Nanomateriais (CT Nano), Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30161-970, Brazil
| | - Ethan Kahn
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Adam Bolotsky
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - He Liu
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ana Laura Elías
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Physics, Binghamton University, Binghamton, New York 13902, United States
| | - Mauricio Terrones
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Research Initiative for Supra Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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3
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Nguyen KL, Wernert V, Denoyel R. Effect of the polydispersity on the dispersion of polymers through silicas having different morphologies (fully porous and core-shell particles and monoliths). J Chromatogr A 2021; 1641:461985. [PMID: 33611113 DOI: 10.1016/j.chroma.2021.461985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/03/2021] [Accepted: 02/05/2021] [Indexed: 11/26/2022]
Abstract
The effect of the polydispersity of polystyrenes on the dispersion through silicas having different morphologies (fully porous, core-shell particles and monoliths) was investigated. The heights equivalent to a theoretical plate (HETP) of those columns were measured for a small molecule (toluene) and a series of polystyrenes of different sizes in non-adsorbing conditions. The different contributions to the total HETP including polydispersity were determined experimentally. The longitudinal diffusion and the mass transfer resistance term were obtained from peak parking experiments. The eddy dispersion was obtained from models and experiments. The effect of polydispersity on the HETP values (Hpoly) can thus be calculated from the total HETP by substraction of the other contributions. The results were compared to the Knox model which surestimates the Hpoly values for porous and core-shell particles which is usually explained by an overestimation of the polydispersity index (PDI) given by the manufacturer. The PDI of two polymers (P02, Mw= 690 g.mol-1 and P03, Mw=1380 g.mol-1) was verified by liquid chromatography by separating each fraction of the polymer on the silica columns by using adsorbing conditions which are obtained with a mixture of heptane and THF. The PDI obtained are comparable to the PDI given by the manufacturer meaning that the assumptions made by Knox are not entirely valid. A direct method is proposed in this paper in order to determine Hpoly. In this method the excess of spreading as compared with a polymer with only one size corresponding to the average size is studied assuming the polymer size distribution is gaussian. The Hpoly values obtained by the direct method are comparable to the experimental values.
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Affiliation(s)
- Khac-Long Nguyen
- Aix-Marseille Université, CNRS, MADIREL, UMR 7246, Centre Saint-Jérôme, F-13397 Marseille cedex 20, France; Hanoi University of Mining and Geology, 18 Vien Street, Bac Tu Liem, Hanoi, Vietnam
| | - Véronique Wernert
- Aix-Marseille Université, CNRS, MADIREL, UMR 7246, Centre Saint-Jérôme, F-13397 Marseille cedex 20, France.
| | - Renaud Denoyel
- Aix-Marseille Université, CNRS, MADIREL, UMR 7246, Centre Saint-Jérôme, F-13397 Marseille cedex 20, France
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The potential use of a gyroid structure to represent monolithic matrices for bioseparation purposes: Fluid dynamics and mass transfer analysis via CFD. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.117594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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5
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Analysis of flow profiles and mass transfer of monolithic chromatographic columns: the geometric influence of channels and tortuosity. BRAZILIAN JOURNAL OF CHEMICAL ENGINEERING 2020. [DOI: 10.1007/s43153-020-00037-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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6
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Wang W, Svidrytski A, Wang D, Villa A, Hahn H, Tallarek U, Kübel C. Quantifying Morphology and Diffusion Properties of Mesoporous Carbon From High-Fidelity 3D Reconstructions. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2019; 25:891-902. [PMID: 31223100 DOI: 10.1017/s1431927619014600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A reliable quantitative analysis in electron tomography, which depends on the segmentation of the three-dimensional reconstruction, is challenging because of constraints during tilt-series acquisition (missing wedge) and reconstruction artifacts introduced by reconstruction algorithms such as the Simultaneous Iterative Reconstruction Technique (SIRT) and Discrete Algebraic Reconstruction Technique (DART). We have carefully evaluated the fidelity of segmented reconstructions analyzing a disordered mesoporous carbon used as support in catalysis. Using experimental scanning transmission electron microscopy (STEM) tomography data as well as realistic phantoms, we have quantitatively analyzed the effect on the morphological description as well as on diffusion properties (based on a random-walk particle-tracking simulation) to understand the role of porosity in catalysis. The morphological description of the pore structure can be obtained reliably both using SIRT and DART reconstructions even in the presence of a limited missing wedge. However, the measured pore volume is sensitive to the threshold settings, which are difficult to define globally for SIRT reconstructions. This leads to noticeable variations of the diffusion coefficients in the case of SIRT reconstructions, whereas DART reconstructions resulted in more reliable data. In addition, the anisotropy of the determined diffusion properties was evaluated, which was significant in the presence of a limited missing wedge for SIRT and strongly reduced for DART.
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Affiliation(s)
- Wu Wang
- Institute of Nanotechnology, Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen,Germany
| | - Artur Svidrytski
- Department of Chemistry,Philipps-Universität Marburg,Hans-Meerwein-Straße 4, 35032 Marburg,Germany
| | - Di Wang
- Institute of Nanotechnology, Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen,Germany
| | - Alberto Villa
- Dipartimento di Chimica,Università degli Studi Milano,via Golgi 19, 20133 Milano,Italy
| | - Horst Hahn
- Institute of Nanotechnology, Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen,Germany
| | - Ulrich Tallarek
- Department of Chemistry,Philipps-Universität Marburg,Hans-Meerwein-Straße 4, 35032 Marburg,Germany
| | - Christian Kübel
- Institute of Nanotechnology, Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen,Germany
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Svidrytski A, Hlushkou D, Tallarek U. Relationship between bed heterogeneity, chord length distribution, and longitudinal dispersion in particulate beds. J Chromatogr A 2019; 1600:167-173. [DOI: 10.1016/j.chroma.2019.04.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/16/2019] [Accepted: 04/17/2019] [Indexed: 10/27/2022]
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8
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Kohns R, Haas CP, Höltzel A, Splith C, Enke D, Tallarek U. Hierarchical silica monoliths with submicron macropores as continuous-flow microreactors for reaction kinetic and mechanistic studies in heterogeneous catalysis. REACT CHEM ENG 2018. [DOI: 10.1039/c8re00037a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The proposed scheme enables academic laboratories to prepare hierarchical silica monoliths as continuous-flow microreactors for kinetic studies in heterogeneous catalysis.
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Affiliation(s)
- Richard Kohns
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
- Institute of Chemical Technology
| | - Christian P. Haas
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Alexandra Höltzel
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Christian Splith
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Dirk Enke
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Ulrich Tallarek
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
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9
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da Silva CGA, Grespan Bottoli CB, Collins CH. 3-Dimensional X-ray microtomography methodology for characterization of monolithic stationary phases and columns for capillary liquid chromatography - A tutorial. Anal Chim Acta 2017; 991:30-45. [PMID: 29031297 DOI: 10.1016/j.aca.2017.08.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 08/22/2017] [Accepted: 08/22/2017] [Indexed: 01/20/2023]
Abstract
In this tutorial we describe a fast, nondestructive, three-dimensional (3-D) view approach to be used in morphology characterization of capillary monoliths and columns by reconstruction from X-ray microtomography (XMT) obtained by acquiring projection images of the sample from a number of different directions. The method comprises imaging acquisition, imaging reconstruction using specific algorithms and imaging analysis by generation of a 3-D image of the sample from radiographic images. The 3-D images show the morphological data for bulk macropore space and skeleton connectivity of the monoliths and were compared with other images from imaging techniques such as scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and with chromatographic performance. The 3-D XMT methodology is applicable for organic and inorganic capillary chromatographic monolithic materials and it allows the acquisition of many hundreds (in our case 1001 projections) of longitudinal and cross-sectional images in a single session, resolving morphological details with a 3D-view of the monolithic structure, inclusive inside the column in a sectional structure with volume (three dimensions) when compared to the sectional structure area (with only two dimensions) when using SEM and FESEM techniques.
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Affiliation(s)
- Carla G A da Silva
- Department of Chemistry, Federal University of Mato Grosso, 78060-900, Cuiabá, Brazil; Institute of Chemistry, University of Campinas, 13083-970, Campinas, Brazil.
| | | | - Carol H Collins
- Institute of Chemistry, University of Campinas, 13083-970, Campinas, Brazil.
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10
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Reising AE, Schlabach S, Baranau V, Stoeckel D, Tallarek U. Analysis of packing microstructure and wall effects in a narrow-bore ultrahigh pressure liquid chromatography column using focused ion-beam scanning electron microscopy. J Chromatogr A 2017; 1513:172-182. [DOI: 10.1016/j.chroma.2017.07.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 07/03/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
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11
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Müllner T, Zankel A, Höltzel A, Svec F, Tallarek U. Morphological Properties of Methacrylate-Based Polymer Monoliths: From Gel Porosity to Macroscopic Inhomogeneities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2205-2214. [PMID: 28186759 DOI: 10.1021/acs.langmuir.7b00337] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Shaping chemical interfaces of hard and soft matter materials into physical morphologies that guarantee excellent transport properties is of central importance for technologies relying on adsorption, separation, and reaction at the interface. Polymer monoliths with a hierarchically structured pore space, for example, are widely used in flow-driven processes, whose efficiency depends on the morphology of the support material over several length scales. Compared with alternative support structures, particularly silica monoliths, polymer monoliths yield lower efficiency, which suggests a suboptimal morphology. Based on physical reconstruction by serial block-face scanning electron microscopy we evaluate the structural features of a methacrylate-based polymer monolith from the pore scale to the column scale. The morphological data reveal a homogeneous polymer skeleton with a solute-impenetrable core-porous shell architecture and a heterogeneous macropore space that suffers from inhomogeneities at the short-range and the transcolumn scale. Although the morphology of the polymer phase is favorable to efficient mass transport, the performance of the polymer monolith is limited by severe transcolumn gradients in macroporosity and macropore size. We propose to overcome these morphological limitations by pursuing a preparation strategy that involves active rather than passive shaping of the macropore space, for example, by using silica monoliths as templating structures for polymer monolith preparation.
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Affiliation(s)
- Tibor Müllner
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Armin Zankel
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, and Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Frantisek Svec
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology , 100029 Beijing, China
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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12
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Haas CP, Müllner T, Kohns R, Enke D, Tallarek U. High-performance monoliths in heterogeneous catalysis with single-phase liquid flow. REACT CHEM ENG 2017. [DOI: 10.1039/c7re00042a] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
On-line control and monitoring in heterogeneous catalysis utilizing high-performance supports allows rapid screening of intrinsic reaction parameters in continuous-flow mode.
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Affiliation(s)
- Christian P. Haas
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Tibor Müllner
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Richard Kohns
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
- Institute of Chemical Technology
| | - Dirk Enke
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Ulrich Tallarek
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
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13
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Enke D, Gläser R, Tallarek U. Sol-Gel and Porous Glass-Based Silica Monoliths with Hierarchical Pore Structure for Solid-Liquid Catalysis. CHEM-ING-TECH 2016. [DOI: 10.1002/cite.201600049] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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14
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Reising AE, Godinho JM, Hormann K, Jorgenson JW, Tallarek U. Larger voids in mechanically stable, loose packings of 1.3μm frictional, cohesive particles: Their reconstruction, statistical analysis, and impact on separation efficiency. J Chromatogr A 2016; 1436:118-32. [PMID: 26858113 DOI: 10.1016/j.chroma.2016.01.068] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/21/2016] [Accepted: 01/24/2016] [Indexed: 12/23/2022]
Abstract
Lateral transcolumn heterogeneities and the presence of larger voids in a packing (comparable to the particle size) can limit the preparation of efficient chromatographic columns. Optimizing and understanding the packing process provides keys to better packing structures and column performance. Here, we investigate the slurry-packing process for a set of capillary columns packed with C18-modified, 1.3μm bridged-ethyl hybrid porous silica particles. The slurry concentration used for packing 75μm i.d. fused-silica capillaries was increased gradually from 5 to 50mg/mL. An intermediate concentration (20mg/mL) resulted in the best separation efficiency. Three capillaries from the set representing low, intermediate, and high slurry concentrations were further used for three-dimensional bed reconstruction by confocal laser scanning microscopy and morphological analysis of the bed structure. Previous studies suggest increased slurry concentrations will result in higher column efficiency due to the suppression of transcolumn bed heterogeneities, but only up to a critical concentration. Too concentrated slurries favour the formation of larger packing voids (reaching the size of the average particle diameter). Especially large voids, which can accommodate particles from>90% of the particle size distribution, are responsible for a decrease in column efficiency at high slurry concentrations. Our work illuminates the increasing difficulty of achieving high bed densities with small, frictional, cohesive particles. As particle size decreases interparticle forces become increasingly important and hinder the ease of particle sliding during column packing. While an optimal slurry concentration is identified with respect to bed morphology and separation efficiency under conditions in this work, our results suggest adjustments of this concentration are required with regard to particle size, surface roughness, column dimensions, slurry liquid, and external effects utilized during the packing process (pressure protocol, ultrasound, electric fields).
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Affiliation(s)
- Arved E Reising
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Justin M Godinho
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, United States
| | - Kristof Hormann
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - James W Jorgenson
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, United States.
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany.
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15
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Hormann K, Baranau V, Hlushkou D, Höltzel A, Tallarek U. Topological analysis of non-granular, disordered porous media: determination of pore connectivity, pore coordination, and geometric tortuosity in physically reconstructed silica monoliths. NEW J CHEM 2016. [DOI: 10.1039/c5nj02814k] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Different approaches are applied and compared, which are universally applicable to quantify pore coordination, pore and pore-throat connectivity, and geometric tortuosity.
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Affiliation(s)
- Kristof Hormann
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Vasili Baranau
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Dzmitry Hlushkou
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Alexandra Höltzel
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Ulrich Tallarek
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
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16
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Müllner T, Unger KK, Tallarek U. Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors. NEW J CHEM 2016. [DOI: 10.1039/c5nj03346b] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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17
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Tanaka N, McCalley DV. Core–Shell, Ultrasmall Particles, Monoliths, and Other Support Materials in High-Performance Liquid Chromatography. Anal Chem 2015; 88:279-98. [DOI: 10.1021/acs.analchem.5b04093] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | - David V. McCalley
- Centre for Research in Biosciences, University of the West of England, Frenchay, Bristol BS16 1QY, U.K
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18
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Müllner T, Zankel A, Lv Y, Svec F, Höltzel A, Tallarek U. Assessing structural correlations and heterogeneity length scales in functional porous polymers from physical reconstructions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:6009-6013. [PMID: 26314251 DOI: 10.1002/adma.201502332] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/16/2015] [Indexed: 06/04/2023]
Abstract
A general, model-free, quantitative approach to the key morphological properties of a porous polymer monolith is presented. After 3D reconstruction, image-based analysis delivers detailed spatial and spatially correlated information on the structural heterogeneities in the void space and the polymer skeleton. Identified heterogeneities, which limit the monolith's performance in targeted applications, are traced back to the preparation process.
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Affiliation(s)
- Tibor Müllner
- Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Armin Zankel
- Graz University of Technology, NAWI Graz, Institute for Electron Microscopy and Nanoanalysis and Center for Electron Microscopy, Steyrergasse 17, 8010, Graz, Austria
| | - Yongqin Lv
- International Research Center for Soft Matter, Beijing University of Chemical Technology, 100029, Beijing, China
| | - Frantisek Svec
- International Research Center for Soft Matter, Beijing University of Chemical Technology, 100029, Beijing, China
| | - Alexandra Höltzel
- Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Ulrich Tallarek
- Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
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19
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Computational investigation of longitudinal diffusion, eddy dispersion, and trans-particle mass transfer in bulk, random packings of core–shell particles with varied shell thickness and shell diffusion coefficient. J Chromatogr A 2015; 1407:139-56. [DOI: 10.1016/j.chroma.2015.06.047] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/09/2015] [Accepted: 06/14/2015] [Indexed: 11/22/2022]
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20
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Stoeckel D, Kübel C, Loeh MO, Smarsly BM, Tallarek U. Morphological Analysis of Physically Reconstructed Silica Monoliths with Submicrometer Macropores: Effect of Decreasing Domain Size on Structural Homogeneity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7391-7400. [PMID: 25654337 DOI: 10.1021/la5046018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Silica monoliths are increasingly used as fixed-bed supports in separation and catalysis because their bimodal pore space architecture combines excellent mass transport properties with a large surface area. To optimize their performance, a quantitative relationship between morphology and transport characteristics has to be established, and synthesis conditions that lead to a desired morphology optimized for a targeted application must be identified. However, the effects of specific synthesis parameters on the structural properties of silica monoliths are still poorly understood. An important question is how far the macropore and domain size can be reduced without compromising the structural homogeneity. We address this question with quantitative morphological data derived for a set of eight macroporous-mesoporous silica monoliths with an average macropore size (d(macro)) of between 3.7 and 0.1 μm, prepared following an established route involving the sol-gel transition and phase separation. The macropore space of the silica monolith samples is reconstructed using focused ion beam scanning electron microscopy followed by a quantitative assessment of geometrical and topological properties based on chord length distributions (CLDs) and branch-node analysis of the pore network, respectively. We observe a significant increase in structural heterogeneity, indicated by a decrease in the parameter k derived from fitting a k-gamma function to the CLDs, when d(macro) reaches the submicrometer range. The compromised structural homogeneity of silica monoliths with submicrometer macropores could possibly originate from early structural freezing during the competitive processes of sol-gel transition and phase separation. It is therefore questionable if the common approach of reducing the morphological features of silica monoliths into the submicrometer regime by changing the point of sol-gel transition can be successful. Alternative strategies and a better understanding of the involved competitive processes should be the focus of future research.
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Affiliation(s)
- Daniela Stoeckel
- †Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
- ‡Institute of Physical Chemistry, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, 35392 Gießen, Germany
| | - Christian Kübel
- §Institute of Nanotechnology and Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Marc O Loeh
- ‡Institute of Physical Chemistry, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, 35392 Gießen, Germany
| | - Bernd M Smarsly
- ‡Institute of Physical Chemistry, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, 35392 Gießen, Germany
| | - Ulrich Tallarek
- †Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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21
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Tran LN, Park JH. Enantiomer separation of acidic chiral compounds on a quinine-silica/zirconia hybrid monolith by capillary electrochromatography. J Chromatogr A 2015; 1396:140-7. [DOI: 10.1016/j.chroma.2015.03.085] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/31/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
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22
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Meinusch R, Hormann K, Hakim R, Tallarek U, Smarsly BM. Synthesis and morphological characterization of phenyl-modified macroporous–mesoporous hybrid silica monoliths. RSC Adv 2015. [DOI: 10.1039/c4ra16519e] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We present a comprehensive approach to characterize the one-pot synthesis, macropore space morphology, and chromatographic performance of phenyl-modified macro–mesoporous silica monoliths.
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Affiliation(s)
- Rafael Meinusch
- Institute of Physical Chemistry
- Justus-Liebig-Universität Giessen
- 35392 Giessen
- Germany
| | - Kristof Hormann
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Romana Hakim
- Institute of Physical Chemistry
- Justus-Liebig-Universität Giessen
- 35392 Giessen
- Germany
- Thermo Fisher Scientific
| | - Ulrich Tallarek
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Bernd M. Smarsly
- Institute of Physical Chemistry
- Justus-Liebig-Universität Giessen
- 35392 Giessen
- Germany
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23
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Hormann K, Tallarek U. Mass transport properties of second-generation silica monoliths with mean mesopore size from 5 to 25nm. J Chromatogr A 2014; 1365:94-105. [DOI: 10.1016/j.chroma.2014.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/03/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
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24
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Causon TJ, Nischang I. Critical differences in chromatographic properties of silica- and polymer-based monoliths. J Chromatogr A 2014; 1358:165-71. [DOI: 10.1016/j.chroma.2014.06.102] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/27/2014] [Accepted: 06/30/2014] [Indexed: 12/20/2022]
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25
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Stoeckel D, Kübel C, Hormann K, Höltzel A, Smarsly BM, Tallarek U. Morphological analysis of disordered macroporous-mesoporous solids based on physical reconstruction by nanoscale tomography. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9022-9027. [PMID: 25036976 DOI: 10.1021/la502381m] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Solids with a hierarchically structured, disordered pore space, such as macroporous-mesoporous silica monoliths, are used as fixed beds in separation and catalysis. Targeted optimization of their functional properties requires a knowledge of the relation among their synthesis, morphology, and mass transport properties. However, an accurate and comprehensive morphological description has not been available for macroporous-mesoporous silica monoliths. Here we offer a solution to this problem based on the physical reconstruction of the hierarchically structured pore space by nanoscale tomography. Relying exclusively on image analysis, we deliver a concise, accurate, and model-free description of the void volume distribution and pore coordination inside the silica monolith. Structural features are connected to key transport properties (effective diffusion, hydrodynamic dispersion) of macropore and mesopore space. The presented approach is applicable to other fixed-bed formats of disordered macroporous-mesoporous solids, such as packings of mesoporous particles and organic-polymer monoliths.
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Affiliation(s)
- Daniela Stoeckel
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse, 35032 Marburg, Germany
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26
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Aggarwal P, Asthana V, Lawson JS, Tolley HD, Wheeler DR, Mazzeo BA, Lee ML. Correlation of chromatographic performance with morphological features of organic polymer monoliths. J Chromatogr A 2014; 1334:20-9. [PMID: 24569008 DOI: 10.1016/j.chroma.2014.01.056] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 01/17/2014] [Accepted: 01/20/2014] [Indexed: 11/27/2022]
Abstract
Monoliths are considered to be a low pressure alternative to particle packed columns for liquid chromatography (LC). However, the chromatographic performance of organic monoliths, in particular, has still not reached the level of particle packed columns. Since chromatographic performance can be attributed to morphological features of the monoliths, in-situ characterization of the monolith structure in three dimensions would provide valuable information that could be used to help improve performance. In this work, serial sectioning and imaging were performed with a dual-beam scanning electron microscope for reconstruction and quantitative characterization of poly(ethylene glycol) diacrylate (PEGDA) monoliths inside a capillary column. Chord lengths, homogeneity factors, porosities and tortuosities were calculated from three-dimensional (3D) reconstructions of two PEGDA monoliths. Chromatographic efficiency was better for the monolith with smaller mean chord length (i.e., 5.23μm), porosity (i.e., 0.49) and tortuosity (i.e., 1.50) compared to values of 5.90μm, 0.59 and 2.34, respectively, for the other monolithic column. Computational prediction of tortuosity (2.32) was found to be in agreement with the experimentally measured value (2.34) for the same column. The monoliths were found to have significant radial heterogeneity since the homogeneity factor decreased from 5.39 to 4.89 (from center to edge) along the column radius.
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Affiliation(s)
- Pankaj Aggarwal
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | | | - John S Lawson
- Department of Statistics, Brigham Young University, Provo, UT 84602, USA
| | - H Dennis Tolley
- Department of Statistics, Brigham Young University, Provo, UT 84602, USA
| | - Dean R Wheeler
- Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA
| | - Brian A Mazzeo
- Department of Electrical Engineering, Brigham Young University, Provo, UT 84602, USA
| | - Milton L Lee
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
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27
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Chan AS, Danquah MK, Agyei D, Hartley PG, Zhu Y. A simple microfluidic chip design for fundamental bioseparation. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2014; 2014:175457. [PMID: 24527255 PMCID: PMC3910460 DOI: 10.1155/2014/175457] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 12/12/2013] [Indexed: 06/03/2023]
Abstract
A microchip pressure-driven liquid chromatographic system with a packed column has been designed and fabricated by using poly(dimethylsiloxane) (PDMS). The liquid chromatographic column was packed with mesoporous silica beads of Ia3d space group. Separation of dyes and biopolymers was carried out to verify the performance of the chip. A mixture of dyes (fluorescein and rhodamine B) and a biopolymer mixture (10 kDa Dextran and 66 kDa BSA) were separated and the fluorescence technique was employed to detect the movement of the molecules. Fluorescein molecule was a nonretained species and rhodamine B was attached onto silica surface when dye mixture in deionized water was injected into the microchannel. The retention times for dextran molecule and BSA molecule in biopolymer separation experiment were 45 s and 120 s, respectively. Retention factor was estimated to be 3.3 for dextran and 10.4 for BSA. The selectivity was 3.2 and resolution was 10.7. Good separation of dyes and biopolymers was achieved and the chip design was verified.
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Affiliation(s)
- Alan S. Chan
- CSIRO Materials Science and Engineering, Highett, VIC 3190, Australia
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Michael K. Danquah
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia
- Department of Chemical Engineering, Curtin University of Technology, Sarawak 98009, Malaysia
| | - Dominic Agyei
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia
| | | | - Yonggang Zhu
- CSIRO Materials Science and Engineering, Highett, VIC 3190, Australia
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28
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Stoeckel D, Wallacher D, Zickler GA, Perlich J, Tallarek U, Smarsly BM. Coherent analysis of disordered mesoporous adsorbents using small angle X-ray scattering and physisorption experiments. Phys Chem Chem Phys 2014; 16:6583-92. [DOI: 10.1039/c3cp55072a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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