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Advances in Industrial Crystallization
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Advances in Industrial Crystallization

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Industrial Crystallization".

Deadline for manuscript submissions: closed (30 June 2020) | Viewed by 61591

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Heike Lorenz

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Guest Editor
Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
Interests: phase equilibria; crystallization kinetics; process monitoring & design; separation of fine chemicals, large scale industrial products and renewable resources; innovative crystallization-based separation concepts; enantiomers; natural products; multi-component mixtures
Special Issues, Collections and Topics in MDPI journals
Dr. Erik Temmel

E-Mail
Guest Editor
DSM Nutritional Products AG, Sisseln, Switzerland" to "Sulzer Chemtech Ltd, Basel, Switzerland
Interests: phase equilibria; crystallization kinetics; continuous crystallization; process monitoring; process design; applied population balance and process modelling; process intensification and combination; process optimization; novel measurement techniques

Special Issue Information

Dear Colleagues,

Crystallization is a key technology utilized in many industries for the manufacture of bulk and fine chemicals, such as agrochemicals, pharmaceutical ingredients and food components. There, the objectives of applying crystallization processes are usually twofold: separation and purification of substances on the one hand and, targeted product design on the other hand. The latter refers to the generation of product particles of desired properties, as purity, a particular solid-state form, crystal size (distribution) or morphology. Process-related target variables include, amongst others, yield, productivity, robustness and costs. The overall process, thus, has to fulfill multiple tasks at same time.

According to the industrial importance and wide application field of crystallization, active research is performed on a broad range of subjects covering fundamentals (e.g. phase equilibria, kinetics and crystallography), analytical tools for crystallization monitoring, separation process design and optimization, product development and, addresses integrated process chains and sustainability issues as well. Considering these variety of potential topics, the scope of this Special Issue on “Advances in Industrial Crystallization” is intentionally broad. We invite interdisciplinary contributions concerning both, understanding crystallization processes and crystallization behavior of compounds, and their applications in commodities and fine chemicals industries and sustainability fields.

Some keywords are given as a guide for submissions to this Special Issue, but research papers dealing with other innovative findings in industrial crystallization are also welcome.

Prof. Heike Lorenz
Dr. Erik Temmel
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Phase equilibria
  • Measurement of crystallization kinetics
  • Crystallization process monitoring
  • Advances in process and product design
  • Industrial applications
  • Separation of complex mixtures
  • Innovative crystallization process concepts and combinations

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Published Papers (16 papers)

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Editorial

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4 pages, 201 KiB  
Editorial
Advances in Industrial Crystallization
by Erik Temmel and Heike Lorenz
Crystals 2020, 10(11), 997; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10110997 - 03 Nov 2020
Cited by 1 | Viewed by 1881
Abstract
Dear colleagues, [...] Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)

Research

Jump to: Editorial

15 pages, 2643 KiB  
Article
Microplates for Crystal Growth and in situ Data Collection at a Synchrotron Beamline
by Miao Liang, Zhijun Wang, Hai Wu, Li Yu, Bo Sun, Huan Zhou, Feng Yu, Qisheng Wang and Jianhua He
Crystals 2020, 10(9), 798; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10090798 - 09 Sep 2020
Cited by 3 | Viewed by 2441
Abstract
An efficient data collection method is important for microcrystals, because microcrystals are sensitive to radiation damage. Moreover, microcrystals are difficult to harvest and locate owing to refraction effects from the surface of the liquid drop or optically invisible, owing to their small size. [...] Read more.
An efficient data collection method is important for microcrystals, because microcrystals are sensitive to radiation damage. Moreover, microcrystals are difficult to harvest and locate owing to refraction effects from the surface of the liquid drop or optically invisible, owing to their small size. Collecting X-ray diffraction data directly from the crystallization devices to completely eliminate the crystal harvesting step is of particular interest. To address these needs, novel microplates combining crystal growth and data collection have been designed for efficient in situ data collection and fully tested at Shanghai Synchrotron Radiation Facility (SSRF) crystallography beamlines. The design of the novel microplates fully adapts the advantage of in situ technology. Thin Kapton membranes were selected to seal the microplate for crystal growth, the crystallization plates can support hanging drop and setting drop vapor diffusion crystallization experiments. Then, the microplate was fixed on a magnetic base and mounted on the goniometer head for in situ data collection. Automatic grid scanning was applied for crystal location with a Blu-Ice data collection system and then in situ data collection was performed. The microcrystals of lysozyme were selected as the testing samples for diffraction data collection using the novel microplates. The results show that this method can achieve comparable data quality to that of the traditional method using the nylon loop. In addition, our method can efficiently and diversely perform data acquisition experiments, and be especially suitable for solving structures of multiple crystals at room temperature or cryogenic temperature. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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26 pages, 8439 KiB  
Article
A Novel Shadowgraphic Inline Measurement Technique for Image-Based Crystal Size Distribution Analysis
by Dominic Wirz, Marc Hofmann, Heike Lorenz, Hans-Jörg Bart, Andreas Seidel-Morgenstern and Erik Temmel
Crystals 2020, 10(9), 740; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10090740 - 21 Aug 2020
Cited by 15 | Viewed by 3208
Abstract
A novel shadowgraphic inline probe to measure crystal size distributions (CSD), based on acquired greyscale images, is evaluated in terms of elevated temperatures and fragile crystals, and compared to well-established, alternative online and offline measurement techniques, i.e., sieving analysis and online microscopy. Additionally, [...] Read more.
A novel shadowgraphic inline probe to measure crystal size distributions (CSD), based on acquired greyscale images, is evaluated in terms of elevated temperatures and fragile crystals, and compared to well-established, alternative online and offline measurement techniques, i.e., sieving analysis and online microscopy. Additionally, the operation limits, with respect to temperature, supersaturation, suspension, and optical density, are investigated. Two different substance systems, potassium dihydrogen phosphate (prisms) and thiamine hydrochloride (needles), are crystallized for this purpose at 25 L scale. Crystal phases of the well-known KH2PO4/H2O system are measured continuously by the inline probe and in a bypass by the online microscope during cooling crystallizations. Both measurement techniques show similar results with respect to the crystal size distribution, except for higher temperatures, where the bypass variant tends to fail due to blockage. Thiamine hydrochloride, a substance forming long and fragile needles in aqueous solutions, is solidified with an anti-solvent crystallization with ethanol. The novel inline probe could identify a new field of application for image-based crystal size distribution measurements, with respect to difficult particle shapes (needles) and elevated temperatures, which cannot be evaluated with common techniques. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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14 pages, 5557 KiB  
Article
Limits of Solid Solutions and Thermal Deformations in the L-Alanine–L-Serine Amino Acid System
by Elena Kotelnikova, Roman Sadovnichii, Lyudmila Kryuchkova and Heike Lorenz
Crystals 2020, 10(7), 618; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10070618 - 16 Jul 2020
Cited by 6 | Viewed by 2440
Abstract
The limits of solid solutions and thermal deformations in the L-alanine–L-serine (L-ala–L-ser) amino acid system have been determined. Thirteen amino acid mixtures with various proportions of the components L-ser/L-ala were studied using powder X-ray diffraction techniques. It was found that the regions of [...] Read more.
The limits of solid solutions and thermal deformations in the L-alanine–L-serine (L-ala–L-ser) amino acid system have been determined. Thirteen amino acid mixtures with various proportions of the components L-ser/L-ala were studied using powder X-ray diffraction techniques. It was found that the regions of solid solutions in the system are rather limited and cover less than 10 mol. % from each component side. The thermal behavior of the components L-ser and L-ala and the composition L-ser/L-ala = 90/10 were studied by temperature-resolved powder X-ray diffraction. The heating of L-ser and L-ala only causes thermal deformations, while two-phase mixtures with the 90/10 L-ser/L-ala ratio form solid solutions at elevated temperatures. Additionally, the parameters of the thermal deformation tensor for L-ser and L-ala were calculated, and the figures of their thermal expansion coefficients were plotted and analyzed. The study conducted is of high applicability, since amino acids are active components of various biological, geological, and technological processes, including those at elevated temperatures, and have numerous applications in life-science industries. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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13 pages, 4488 KiB  
Article
The Steps from Batchwise to Continuous Crystallization for a Fine Chemical: A Case Study
by Christian Melches, Hermann Plate, Jürgen Schürhoff and Robert Buchfink
Crystals 2020, 10(6), 542; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10060542 - 24 Jun 2020
Cited by 11 | Viewed by 5734
Abstract
Many processes to produce fine chemicals and precursors of pharmaceuticals are still operated in batchwise mode. However, recently, more producers have taken a change to continuous operation mode into consideration, performing studies and trials on such a change, while some have even already [...] Read more.
Many processes to produce fine chemicals and precursors of pharmaceuticals are still operated in batchwise mode. However, recently, more producers have taken a change to continuous operation mode into consideration, performing studies and trials on such a change, while some have even already exchanged their production mode from batchwise to continuous operation. In this paper, the stepwise development from an initial idea to industrial implementation via laboratory testing and confirmation is revealed through the example of an organic fine chemical from the perspective of a crystallization plant manufacturer. We begin with the definition of the objectives of the project and a brief explanation of the advantages of continuous operation and the associated product properties. The results of the laboratory tests, confirming the assumptions made upfront, are reported and discussed. Finally, the implementation of an industrial plant using a draft tube baffled (DTB) crystallizer and the final product properties are shown. Product properties such as crystal size distribution, crystal shape, related storage stability and flowability have successfully been improved. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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15 pages, 3769 KiB  
Article
Systematic Investigations on Continuous Fluidized Bed Crystallization for Chiral Separation
by Erik Temmel, Jonathan Gänsch, Andreas Seidel-Morgenstern and Heike Lorenz
Crystals 2020, 10(5), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10050394 - 14 May 2020
Cited by 9 | Viewed by 3190
Abstract
A recently developed continuous enantioseparation process utilizing two coupled fluidized bed crystallizers is systematically investigated to identify essential correlations between different operation parameters and the corresponding process performance on the example of asparagine monohydrate. Based on liquid phase composition and product crystal size [...] Read more.
A recently developed continuous enantioseparation process utilizing two coupled fluidized bed crystallizers is systematically investigated to identify essential correlations between different operation parameters and the corresponding process performance on the example of asparagine monohydrate. Based on liquid phase composition and product crystal size distribution data, it is proven that steady state operation is achieved reproducibly in a relatively short time. The process outputs at steady state are compared for different feed flow rates, supersaturations, and crystallization temperatures. It is shown that purities >97% are achieved with productivities up to 40 g/L/h. The size distribution, which depends almost exclusively on the liquid flow rate, can be easily adjusted between 260 and 330 µm (mean size) with an almost constant standard deviation of ±55 µm. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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13 pages, 2805 KiB  
Article
Concept Study for an Integrated Reactor-Crystallizer Process for the Continuous Biocatalytic Synthesis of (S)-1-(3-Methoxyphenyl)ethylamine
by Dennis Hülsewede, Erik Temmel, Peter Kumm and Jan von Langermann
Crystals 2020, 10(5), 345; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10050345 - 27 Apr 2020
Cited by 12 | Viewed by 3607
Abstract
An integrated biocatalysis-crystallization concept was developed for the continuous amine transaminase-catalyzed synthesis of (S)-1-(3-methoxyphenyl)ethylamine, which is a valuable intermediate for the synthesis of rivastigmine, a highly potent drug for the treatment of early stage Alzheimer’s disease. The three-part vessel system developed [...] Read more.
An integrated biocatalysis-crystallization concept was developed for the continuous amine transaminase-catalyzed synthesis of (S)-1-(3-methoxyphenyl)ethylamine, which is a valuable intermediate for the synthesis of rivastigmine, a highly potent drug for the treatment of early stage Alzheimer’s disease. The three-part vessel system developed for this purpose consists of a membrane reactor for the continuous synthesis of the product amine, a saturator vessel for the continuous supply of the amine donor isopropylammonium and the precipitating reagent 3,3-diphenylpropionate and a crystallizer in which the product amine can continuously precipitate as (S)-1-(3-methoxyphenyl)ethylammonium-3,3-diphenylpropionate. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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16 pages, 3566 KiB  
Article
Solvent Effects on Catechol Crystal Habits and Aspect Ratios: A Combination of Experiments and Molecular Dynamics Simulation Study
by Dan Zhu, Shihao Zhang, Pingping Cui, Chang Wang, Jiayu Dai, Ling Zhou, Yaohui Huang, Baohong Hou, Hongxun Hao, Lina Zhou and Qiuxiang Yin
Crystals 2020, 10(4), 316; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10040316 - 18 Apr 2020
Cited by 16 | Viewed by 3989
Abstract
This work could help to better understand the solvent effects on crystal habits and aspect ratio changes at the molecular level, which provide some guidance for solvent selection in industrial crystallization processes. With the catechol crystal habits acquired using both experimental and simulation [...] Read more.
This work could help to better understand the solvent effects on crystal habits and aspect ratio changes at the molecular level, which provide some guidance for solvent selection in industrial crystallization processes. With the catechol crystal habits acquired using both experimental and simulation methods in isopropanol, methyl acetate and ethyl acetate, solvent effects on crystal morphology were explored based on the modified attachment energy model. Firstly, morphologically dominant crystal faces were obtained with the predicted crystal habit in vacuum. Then, modified attachment energies were calculated by the molecular dynamics simulation to modify the crystal shapes in a real solvent environment, and the simulation results were in agreement with the experimental ones. Meanwhile, the surface properties such as roughness and the diffusion coefficient were introduced to analyze the solvent adsorption behaviors and the radial distribution function curves were generated to distinguish diverse types of interactions like hydrogen bonds and van der Waals forces. Results show that the catechol crystal habits were affected by the combination of the attachment energy, surface structures and molecular interaction types. Moreover, the changing aspect ratios of catechol crystals are closely related to the existence of hydrogen bonds which contribute to growth inhibition on specific faces. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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16 pages, 2364 KiB  
Article
Gypsum Crystallization during Reverse Osmosis Desalination of Water with High Sulfate Content in Presence of a Novel Fluorescent-Tagged Polyacrylate
by Maxim Oshchepkov, Vladimir Golovesov, Anastasia Ryabova, Anatoly Redchuk, Sergey Tkachenko, Alexei Pervov and Konstantin Popov
Crystals 2020, 10(4), 309; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10040309 - 16 Apr 2020
Cited by 18 | Viewed by 3936
Abstract
Gypsum scaling in reverse osmosis (RO) desalination process is studied in presence of a novel fluorescent 1,8-naphthalimide-tagged polyacrylate (PAA-F1) by fluorescent microscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS) and a particle counter technique. A comparison of PAA-F1 with a previously reported [...] Read more.
Gypsum scaling in reverse osmosis (RO) desalination process is studied in presence of a novel fluorescent 1,8-naphthalimide-tagged polyacrylate (PAA-F1) by fluorescent microscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS) and a particle counter technique. A comparison of PAA-F1 with a previously reported fluorescent bisphosphonate HEDP-F revealed a better PAA-F1 efficacy, and a similar behavior of polyacrylate and bisphosphonate inhibitors under the same RO experimental conditions. Despite expectations, PAA-F1 does not interact with gypsum. For both reagents, it is found that scaling takes place in the bulk retentate phase via heterogeneous nucleation step. The background “nanodust” plays a key role as a gypsum nucleation center. Contrary to popular belief, an antiscalant interacts with “nanodust” particles, isolating them from calcium and sulfate ions sorption. Therefore, the number of gypsum nucleation centers is reduced, and in turn, the overall scaling rate is diminished. It is also shown that, the scale formation scenario changes from the bulk medium, in the beginning, to the sediment crystals growth on the membrane surface, at the end of the desalination process. It is demonstrated that the fluorescent-tagged antiscalants may become very powerful tools in membrane scaling inhibition studies. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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16 pages, 3376 KiB  
Article
Purification of Curcumin from Ternary Extract-Similar Mixtures of Curcuminoids in a Single Crystallization Step
by Elena Horosanskaia, Lina Yuan, Andreas Seidel-Morgenstern and Heike Lorenz
Crystals 2020, 10(3), 206; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10030206 - 16 Mar 2020
Cited by 23 | Viewed by 10631
Abstract
Crystallization-based separation of curcumin from ternary mixtures of curcuminoids having compositions comparable to commercial extracts was studied experimentally. Based on solubility and supersolubility data of both, pure curcumin and curcumin in presence of the two major impurities demethoxycurcumin (DMC) and bis(demethoxy)curcumin (BDMC), seeded [...] Read more.
Crystallization-based separation of curcumin from ternary mixtures of curcuminoids having compositions comparable to commercial extracts was studied experimentally. Based on solubility and supersolubility data of both, pure curcumin and curcumin in presence of the two major impurities demethoxycurcumin (DMC) and bis(demethoxy)curcumin (BDMC), seeded cooling crystallization procedures were derived using acetone, acetonitrile and 50/50 (wt/wt) mixtures of acetone/2-propanol and acetone/acetonitrile as solvents. Starting from initial curcumin contents of 67–75% in the curcuminoid mixtures single step crystallization processes provided crystalline curcumin free of BDMC at residual DMC contents of 0.6–9.9%. Curcumin at highest purity of 99.4% was obtained from a 50/50 (wt/wt) acetone/2-propanol solution in a single crystallization step. It is demonstrated that the total product yield can be significantly enhanced via addition of water, 2-propanol and acetonitrile as anti-solvents at the end of a cooling crystallization process. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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15 pages, 3425 KiB  
Article
TiO2-Seeded Hydrothermal Growth of Spherical BaTiO3 Nanocrystals for Capacitor Energy-Storage Application
by Ming Li, Lulu Gu, Tao Li, Shiji Hao, Furui Tan, Deliang Chen, Deliang Zhu, Yongjun Xu, Chenghua Sun and Zhenyu Yang
Crystals 2020, 10(3), 202; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10030202 - 14 Mar 2020
Cited by 18 | Viewed by 4940
Abstract
Simple but robust growth of spherical BaTiO3 nanoparticles with uniform nanoscale sizes is of great significance for the miniaturization of BaTiO3-based electron devices. This paper reports a TiO2-seeded hydrothermal process to synthesize spherical BaTiO3 nanoparticles with a [...] Read more.
Simple but robust growth of spherical BaTiO3 nanoparticles with uniform nanoscale sizes is of great significance for the miniaturization of BaTiO3-based electron devices. This paper reports a TiO2-seeded hydrothermal process to synthesize spherical BaTiO3 nanoparticles with a size range of 90–100 nm using TiO2 (Degussa) and Ba(NO3)2 as the starting materials under an alkaline (NaOH) condition. Under the optimum conditions ([NaOH] = 2.0 mol L−1, RBa/Ti = 2.0, T = 210 °C and t = 8 h), the spherical BaTiO3 nanoparticles obtained exhibit a narrow size range of 91 ± 14 nm, and the corresponding BaTiO3/polymer/Al film is of a high dielectric constant of 59, a high break strength of 102 kV mm−1, and a low dielectric loss of 0.008. The TiO2-seeded hydrothermal growth has been proved to be an efficient process to synthesize spherical BaTiO3 nanoparticles for potential capacitor energy-storage applications. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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18 pages, 5595 KiB  
Article
Stereoselective Crystallization of Chiral 3,4-Dimethylphenyl Glycerol Ether Complicated by Plurality of Crystalline Modifications
by Alexander A. Bredikhin, Dmitry V. Zakharychev, Zemfira A. Bredikhina, Alexey V. Kurenkov, Aida I. Samigullina and Aidar T. Gubaidullin
Crystals 2020, 10(3), 201; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10030201 - 14 Mar 2020
Cited by 4 | Viewed by 2600
Abstract
Spontaneous resolution of Pasteur’s salt was historically the first way to obtain pure enantiomers from the racemate. The current increase in interest in the direct racemates resolution during crystallization is largely due to the opened prospects for the industrial application of this approach. [...] Read more.
Spontaneous resolution of Pasteur’s salt was historically the first way to obtain pure enantiomers from the racemate. The current increase in interest in the direct racemates resolution during crystallization is largely due to the opened prospects for the industrial application of this approach. The chiral 3-(3,4-dimethylphenoxy) propane-1,2-diol 1 is a synthetic precursor of practically useful amino alcohols, the enantiomers of which exhibit different biological effects. In this work, it was first discovered that racemic diol 1 is prone to spontaneous resolution. However, the crystallization process is complicated by the existence, along with the conglomerate, of two other crystalline forms. Using the differential scanning calorimetry (DSC) approach, methods have been developed to obtain individual metastable phases, and all identified modifications ((R)-1, (R+S)-1, α-rac-1, β-rac-1) were ranked by energy. The IR spectroscopy and powder X-ray diffraction (PXRD) methods demonstrated the identity of the first two forms and their proximity to the third, while β-rac-1 is significantly different from the rest. The crystal structure of the forms (R)-1 and α-rac-1 was established by the single crystal X-ray diffraction (SC-XRD) method. Preliminary information on the structure of β-rac-1 phase was obtained by the PXRD approach. Based on the information received, the experimental conditions for a successful direct resolution of racemic 1 into individual enantiomers by a preferential crystallization procedure were selected. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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13 pages, 1889 KiB  
Article
Impact of the Surface Properties of Cellulose Nanocrystals on the Crystallization Kinetics of Poly(Butylene Succinate)
by Hatem Abushammala and Jia Mao
Crystals 2020, 10(3), 196; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10030196 - 13 Mar 2020
Cited by 17 | Viewed by 2782
Abstract
The hydrophilicity of cellulose nanocrystals (CNCs) is a major challenge for their processing with hydrophobic polymers and matrices. As a result, many surface modifications have been proposed to hydrophobize CNCs. The authors showed in an earlier study that grafting alcohols of different chain [...] Read more.
The hydrophilicity of cellulose nanocrystals (CNCs) is a major challenge for their processing with hydrophobic polymers and matrices. As a result, many surface modifications have been proposed to hydrophobize CNCs. The authors showed in an earlier study that grafting alcohols of different chain lengths onto the surface of CNCs using toluene diisocyanate (TDI) as a linker can systematically hydrophobize CNCs to a water contact angle of up to 120° depending on the alcohol chain length. Then, the hydrophobized CNCs were used to mechanically reinforce poly(butylene succinate) (PBS), which is a hydrophobic polymer. As a result of hydrophobization, PBS/CNCs interfacial adhesion and the composite mechanical properties significantly improved with the increasing CNC contact angle. Continuing on these results, this paper investigates the impact of CNC surface properties on the crystallization behavior of PBS using differential scanning calorimetry (DSC). The results showed that the crystallization temperature of PBS increased from 74.7 °C to up to 86.6 °C as a result of CNC nucleation activity, and its value was proportionally dependent on the contact angle of the CNCs. In agreement, the nucleation activity factor (φ) estimated using Dobreva and Gutzow’s method decreased with the increasing CNC contact angle. Despite the nucleation action of CNCs, the rate constant of PBS crystallization as estimated using the Avrami model decreased in general as a result of a prevailing impeding effect. This decrease was minimized with increasing the contact angle of the CNCs. The impeding effect also increased the average activation energy of crystallization, which was estimated using the Kissinger method. Moreover, the Avrami exponent (n) decreased because of CNC addition, implying a heterogeneous crystallization, which was also apparent in the crystallization thermograms. Overall, the CNC addition facilitated PBS nucleation but retarded its crystallization, and both processes were significantly affected by the surface properties of the CNCs. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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14 pages, 2397 KiB  
Article
Freeze Concentration of Aqueous [DBNH][OAc] Ionic Liquid Solution
by Nahla Osmanbegovic, Lina Yuan, Heike Lorenz and Marjatta Louhi-Kultanen
Crystals 2020, 10(3), 147; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10030147 - 26 Feb 2020
Cited by 14 | Viewed by 3511
Abstract
In the present work, freeze crystallization studies, as a novel concentration method for aqueous 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]) ionic liquid solution, were conducted. In order to find the appropriate temperature and composition range for freeze crystallization, the solid–liquid equilibrium of a binary [DBNH][OAc]–water compound [...] Read more.
In the present work, freeze crystallization studies, as a novel concentration method for aqueous 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]) ionic liquid solution, were conducted. In order to find the appropriate temperature and composition range for freeze crystallization, the solid–liquid equilibrium of a binary [DBNH][OAc]–water compound system was investigated with differential scanning calorimetry (DSC). Results of this analysis showed that the melting temperature of the pure ionic liquid was 58 ℃, whereas the eutectic temperature of the binary compound system was found to be −73 ℃. The activity coefficient of water was determined based on the freezing point depression data obtained in this study. In this study, the lowest freezing point was −1.28 ℃ for the aqueous 6 wt.% [DBNH][OAc] solution. Ice crystal yield and distribution coefficient were obtained for two types of aqueous solutions (3 wt.% and 6 wt.% [DBNH][OAc]), and two freezing times (40 min and 60 min) were used as the main parameters to compare the two melt crystallization methods: static layer freeze and suspension freeze crystallization. Single-step suspension freeze crystallization resulted in higher ice crystal yields and higher ice purities when compared with the single-step static layer freeze crystallization. The distribution coefficient values obtained showed that the impurity ratios in ice and in the initial solution for suspension freeze crystallization were between 0.11 and 0.36, whereas for static layer freeze crystallization these were between 0.28 and 0.46. Consequently, suspension freeze crystallization is a more efficient low-energy separation method than layer freeze crystallization for the aqueous-ionic liquid solutions studied and, therefore, this technique can be applied as a concentration method for aqueous-ionic liquid solutions. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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15 pages, 3884 KiB  
Article
Numerical Model Study of Multiple Dendrite Motion Behavior in Melt Based on LBM-CA Method
by Yu Bai, Yingming Wang, Shijie Zhang, Qi Wang and Ri Li
Crystals 2020, 10(2), 70; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10020070 - 27 Jan 2020
Cited by 5 | Viewed by 2128
Abstract
In this paper, a new method is proposed to solve the solute field of moving grains, and a Cellular automaton (CA)-Lattice Boltzmann method (LBM)-Semi rebound format(Ladd) coupling model which can accurately simulate the motion behavior of multiple dendrites is established. The growth process [...] Read more.
In this paper, a new method is proposed to solve the solute field of moving grains, and a Cellular automaton (CA)-Lattice Boltzmann method (LBM)-Semi rebound format(Ladd) coupling model which can accurately simulate the motion behavior of multiple dendrites is established. The growth process of microstructure in the solidification process of Al-4.7% Cu alloy ingot was calculated by Cellular automaton (CA) method, the momentum, heat, and mass transfer processes were calculated by Lattice Boltzmann method (LBM), and the melt-dendrite sharp interface interaction was treated by Ladd method. The reliability of the model is verified, and then the growth and movement of single dendrite and multiple dendrites under the action of gravity field are simulated. The simulation results show that the growth and movement mode of multiple dendrites are quite different from that of single dendrite, which is shown in two aspects: (1) the original motion state of dendrites is changed by the combination of flow field, which slows down the falling speed of dendrites to a certain extent; (2) the fusion of solute field between dendrites changed the original growth mode of boundary dendrites and increased their rotation speed. Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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15 pages, 5985 KiB  
Article
Effects of Synthesis Parameters on Crystallization Behavior of K-MER Zeolite and Its Morphological Properties on Catalytic Cyanoethylation Reaction
by Ying-Wai Cheong, Ka-Lun Wong, Boon Seng Ooi, Tau Chuan Ling, Fitri Khoerunnisa and Eng-Poh Ng
Crystals 2020, 10(2), 64; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10020064 - 23 Jan 2020
Cited by 8 | Viewed by 3211
Abstract
MER-type zeolite is an interesting microporous material that has been widely used in catalysis and separation. By carefully controlling the synthesis parameters, a procedure to synthesize K-MER zeolite crystals with various morphologies has been developed. The silica, water and mineralizer content in the [...] Read more.
MER-type zeolite is an interesting microporous material that has been widely used in catalysis and separation. By carefully controlling the synthesis parameters, a procedure to synthesize K-MER zeolite crystals with various morphologies has been developed. The silica, water and mineralizer content in the synthesis gel, as well as crystallization time and temperature, have a profound impact on the crystallization kinetics, resulting in zeolite solids with various degrees of crystallinity, crystal sizes and shapes. K-MER zeolite crystals with nanorod, bullet-like, prismatic and wheatsheaf-like morphologies have been successfully obtained. The catalytic performances of the K-MER zeolites in cyanoethylation of methanol, under novel non-microwave instant heating, have been investigated. The zeolite in nanosize form shows the best catalytic performance (94.1% conversion, 100% selectivity) while the bullet-like zeolite gives poorest catalytic performance (44.2% conversion, 100% selectivity). Full article
(This article belongs to the Special Issue Advances in Industrial Crystallization)
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