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4 pages, 201 KiB

Open AccessEditorial

Advances in Industrial Crystallization

by Erik Temmel and Heike Lorenz

Crystals 2020, 10(11), 997; https://doi.org/10.3390/cryst10110997 - 3 Nov 2020

Cited by 1 | Viewed by 2252

Abstract

Dear colleagues, [...] Full article

(This article belongs to the Special Issue Advances in Industrial Crystallization)

Research

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15 pages, 2643 KiB

Open AccessEditor’s ChoiceArticle

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://doi.org/10.3390/cryst10090798 - 9 Sep 2020

Cited by 6 | Viewed by 2887

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

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26 pages, 8439 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10090740 - 21 Aug 2020

Cited by 16 | Viewed by 3673

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

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14 pages, 5557 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10070618 - 16 Jul 2020

Cited by 7 | Viewed by 2891

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

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13 pages, 4488 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10060542 - 24 Jun 2020

Cited by 12 | Viewed by 6678

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

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15 pages, 3769 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10050394 - 14 May 2020

Cited by 11 | Viewed by 3690

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

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13 pages, 2805 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10050345 - 27 Apr 2020

Cited by 14 | Viewed by 4090

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

Open AccessArticle

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://doi.org/10.3390/cryst10040316 - 18 Apr 2020

Cited by 17 | Viewed by 4621

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

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16 pages, 2364 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10040309 - 16 Apr 2020

Cited by 19 | Viewed by 4555

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

Open AccessFeature PaperArticle

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://doi.org/10.3390/cryst10030206 - 16 Mar 2020

Cited by 28 | Viewed by 11900

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

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15 pages, 3425 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10030202 - 14 Mar 2020

Cited by 19 | Viewed by 5744

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, R_Ba/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

Open AccessArticle

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://doi.org/10.3390/cryst10030201 - 14 Mar 2020

Cited by 5 | Viewed by 2958

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

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13 pages, 1889 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10030196 - 13 Mar 2020

Cited by 18 | Viewed by 3251

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

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14 pages, 2397 KiB

Open AccessArticle

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://doi.org/10.3390/cryst10030147 - 26 Feb 2020

Cited by 15 | Viewed by 4009

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

Open AccessArticle

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://doi.org/10.3390/cryst10020070 - 27 Jan 2020

Cited by 6 | Viewed by 2473

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

Open AccessArticle

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://doi.org/10.3390/cryst10020064 - 23 Jan 2020

Cited by 10 | Viewed by 3824

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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