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Crystals
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Advances in Ultrasound Stimulated Crystallization
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Advances in Ultrasound Stimulated Crystallization

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 July 2018) | Viewed by 63147

Special Issue Editor

Dr. Judy Lee

E-Mail Website
Guest Editor
School of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, UK
Interests: acoustic cavitation; sonoluminescence; ultrasound processing; sonocrystallisation; membrane filtrations
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is my great pleasure to introduce to you all the exciting Special Issue on “Advances in Ultrasound Stimulated Crystallization”. Crystallization is an important industrial process and the benefits of ultrasound in crystallization is well known but poorly understood. No doubt to the researchers in this field, the mechanism behind sonocrystallization is still contentious. This is not surprising considering ultrasound induce cavitation and crystallization processes are two complex dynamic systems, and when coupled together this complexity is compounded. 

This Special Issue hopes to bring together research which showcases the advances in the application of ultrasound in crystallization processes and in particular any work which could shed some light on the mechanism behind sonocrystallization.

Dr. Judy Lee
Guest Editor

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 2100 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

  • Sonocrystallization
  • Polymorphism
  • Crystal Nucleation
  • Acoustic Cavitation

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Published Papers (7 papers)

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Research

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11 pages, 2435 KiB  
Article
Reducing the Induction Time Using Ultrasound and High-Shear Mixing in a Continuous Crystallization Process
by Arne Vancleef, Stijn Seurs, Jeroen Jordens, Tom Van Gerven, Leen C. J. Thomassen and Leen Braeken
Crystals 2018, 8(8), 326; https://doi.org/10.3390/cryst8080326 - 14 Aug 2018
Cited by 27 | Viewed by 6619
Abstract
Continuous crystallization in tubular crystallizers is of particular interest to the pharmaceutical industry to accurately control average particle size, particle size distribution, and (polymorphic) shape. However, these types of crystallizers require fast nucleation, and thus, short induction times at the beginning of the [...] Read more.
Continuous crystallization in tubular crystallizers is of particular interest to the pharmaceutical industry to accurately control average particle size, particle size distribution, and (polymorphic) shape. However, these types of crystallizers require fast nucleation, and thus, short induction times at the beginning of the flow process, which is challenging for larger and complex organic molecules. High shear and/or the presence of bubbles were identified to influence the nucleation behavior. This work investigates the effects of both high-shear mixing and ultrasound on the anti-solvent crystallization of paracetamol in acetone–water. Both devices generate intense amounts of shear and gas bubbles. Generally, the results show that increasing input power decreases the induction time significantly for both the rotor–stator mixer and ultrasound probe. However, the induction time is almost independent of the supersaturation for the ultrasound probe, while the induction time significantly increases with decreasing supersaturation for the rotor–stator mixer. In contrast, the particle size distribution for the rotor–stator mixer is independent of the supersaturation, while increasing supersaturation decreases the particle size for the ultrasound probe. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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13 pages, 2853 KiB  
Article
Antisolvent Sonocrystallisation of Sodium Chloride and the Evaluation of the Ultrasound Energy Using Modified Classical Nucleation Theory
by Judy Lee and Shanshan Yang
Crystals 2018, 8(8), 320; https://doi.org/10.3390/cryst8080320 - 10 Aug 2018
Cited by 16 | Viewed by 5538
Abstract
The crystal nucleation rate of sodium chloride in ethanol was investigated by measuring the induction time at various supersaturation ratios under silent and ultrasound irradiation at frequencies between 22 and 500 kHz. Under silent conditions, the data follows the classical nucleation theory showing [...] Read more.
The crystal nucleation rate of sodium chloride in ethanol was investigated by measuring the induction time at various supersaturation ratios under silent and ultrasound irradiation at frequencies between 22 and 500 kHz. Under silent conditions, the data follows the classical nucleation theory showing both the homogeneous and heterogeneous regions and giving an interfacial surface tension of 31.0 mN m−2. Sonication led to a non-linearity in the data and was fitted by a modified classical nucleation theory to account for the additional free energy being supplemented by sonication. For 98 kHz, this free energy increased from 1.33 × 108 to 1.90 × 108 J m−3 for sonication powers of 2 to 15 W, respectively. It is speculated that the energy was supplemented by the localised bubble collapses and collisions. Increasing the frequency from 22 to 500 kHz revealed that a minimum induction time was obtained at frequencies between 44 and 98 kHz, which has been attributed to the overall collapse intensity being the strongest at these frequencies. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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13 pages, 2430 KiB  
Article
Sonocrystallization—Case Studies of Salicylamide Particle Size Reduction and Isoniazid Derivative Synthesis and Crystallization
by Zhen-Yu Yang, Shih-Kuo Yen, Wei-Syun Hu, Yu-Zhe Huang, Tsung-Mao Yang and Chie-Shaan Su
Crystals 2018, 8(6), 249; https://doi.org/10.3390/cryst8060249 - 15 Jun 2018
Cited by 4 | Viewed by 4929
Abstract
Two case studies of salicylamide particle size reduction and isoniazid derivative synthesis and crystallization realized using sonocrystallization were investigated. The size, habit, structure, thermal behavior, and spectrometric properties of sonocrystallized crystals were analyzed through scanning electron microscopy (SEM), powder X-ray diffractometry (PXRD), differential [...] Read more.
Two case studies of salicylamide particle size reduction and isoniazid derivative synthesis and crystallization realized using sonocrystallization were investigated. The size, habit, structure, thermal behavior, and spectrometric properties of sonocrystallized crystals were analyzed through scanning electron microscopy (SEM), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The effects of the operating parameters, such as sonication intensity, sonication duration, and solution concentration, on sonocrystallization were compared. The crystal size of salicylamide was reduced from 595 μm (the original size) and was efficiently manipulated to be between 40 and 80 μm. Moreover, compared with the crystal habits of unprocessed crystals and recrystallized crystals fabricated through conventional methods, the crystal habit of salicylamide could be modified to present a regular shape. The structure, thermal behavior, and spectrometric properties of sonocrystallized salicylamide were found to be in agreement with those of an unprocessed sample. For producing isoniazid derivative crystals, N′-(propan-2-ylidene)-isonicotinohydrazide was synthesized using isoniazid in acetone at 318 K. The resulting solution was then cooled by applying power ultrasound to isolate N′-(propan-2-ylidene)-isonicotinohydrazide crystals. The solid-state properties of the synthesized N′-(propan-2-ylidene)-isonicotinohydrazide was verified through PXRD, DSC, and FTIR spectroscopy. The feasibility of particle size manipulation was then demonstrated through sonocrystallization. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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18121 KiB  
Article
The Effect of Ultrasound on the Crystallisation of Paracetamol in the Presence of Structurally Similar Impurities
by Thai T. H. Nguyen, Azeem Khan, Layla M. Bruce, Clarissa Forbes, Richard L. O’Leary and Chris J. Price
Crystals 2017, 7(10), 294; https://doi.org/10.3390/cryst7100294 - 30 Sep 2017
Cited by 21 | Viewed by 11712
Abstract
Sono-crystallisation has been used to enhance crystalline product quality particularly in terms of purity, particle size and size distribution. In this work, the effect of impurities and ultrasound on crystallisation processes (nucleation temperature, yield) and crystal properties (crystal size distribution determined by Focused [...] Read more.
Sono-crystallisation has been used to enhance crystalline product quality particularly in terms of purity, particle size and size distribution. In this work, the effect of impurities and ultrasound on crystallisation processes (nucleation temperature, yield) and crystal properties (crystal size distribution determined by Focused Beam Reflectance Measurement (FBRM), crystal habit, filtration rate and impurity content in the crystal product by Liquid Chromatography-Mass Spectroscopy (LC-MS)) were investigated in bulk suspension crystallisation experiments with and without the use of ultrasound. The results demonstrate that ultrasonic intervention has a significant effect on both crystallisation and product crystal properties. It increases the nucleation rate resulting in smaller particles and a narrower Particle Size Distribution (PSD), the yield has been shown to be increase as has the product purity. The effect of ultrasound is to reduce the level acetanilide impurity incorporated during growth from a 2 mol% solution of the selected impurity from 0.85 mol% to 0.35 mol% and likewise ultrasound reduces the uptake of metacetamol from 1.88 mol% to 1.52 mol%. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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4752 KiB  
Article
Ultrasound Assisted Particle Size Control by Continuous Seed Generation and Batch Growth
by Jeroen Jordens, Enio Canini, Bjorn Gielen, Tom Van Gerven and Leen Braeken
Crystals 2017, 7(7), 195; https://doi.org/10.3390/cryst7070195 - 29 Jun 2017
Cited by 23 | Viewed by 6418
Abstract
Controlling particle size is essential for crystal quality in the chemical and pharmaceutical industry. Several articles illustrate the potential of ultrasound to tune this particle size during the crystallization process. This paper investigates how ultrasound can control the particle size distribution (PSD) of [...] Read more.
Controlling particle size is essential for crystal quality in the chemical and pharmaceutical industry. Several articles illustrate the potential of ultrasound to tune this particle size during the crystallization process. This paper investigates how ultrasound can control the particle size distribution (PSD) of acetaminophen crystals by continuous seed generation in a tubular crystallizer followed by batch growth. It is demonstrated that the supersaturation ratio at which ultrasound starts seed generation has a substantial effect on the final PSD while the applied power is insignificant in the studied conditions. The higher the supersaturation ratio, the smaller the final crystals become up to a supersaturation ratio of 1.56. Furthermore, it was shown that ultrasound can also impact the final PSD when applied during the growth phase. Frequencies of 850 kHz or below reduce the final particle size; the lower the applied frequency, the smaller the crystals become. In conclusion, one could state that ultrasound is able to control the particle size during seed generation and subsequent growth until the final particle size. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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30154 KiB  
Article
Agglomeration Control during Ultrasonic Crystallization of an Active Pharmaceutical Ingredient
by Bjorn Gielen, Jeroen Jordens, Leen C. J. Thomassen, Leen Braeken and Tom Van Gerven
Crystals 2017, 7(2), 40; https://doi.org/10.3390/cryst7020040 - 8 Feb 2017
Cited by 55 | Viewed by 11890
Abstract
Application of ultrasound during crystallization can efficiently inhibit agglomeration. However, the mechanism is unclear and sonication is usually enabled throughout the entire process, which increases the energy demand. Additionally, improper operation results in significant crystal damage. Therefore, the present work addresses these issues [...] Read more.
Application of ultrasound during crystallization can efficiently inhibit agglomeration. However, the mechanism is unclear and sonication is usually enabled throughout the entire process, which increases the energy demand. Additionally, improper operation results in significant crystal damage. Therefore, the present work addresses these issues by identifying the stage in which sonication impacts agglomeration without eroding the crystals. This study was performed using a commercially available API that showed a high tendency to agglomerate during seeded crystallization. The crystallization progress was monitored using process analytical tools (PAT), including focus beam reflectance measurements (FBRM) to track to crystal size and number and Fourier transform infrared spectroscopy (FTIR) to quantify the supersaturation level. These tools provided insight in the mechanism by which ultrasound inhibits agglomeration. A combination of improved micromixing, fast crystal formation which accelerates depletion of the supersaturation and a higher collision frequency prevent crystal cementation to occur. The use of ultrasound as a post-treatment can break some of the agglomerates, but resulted in fractured crystals. Alternatively, sonication during the initial seeding stage could assist in generating nuclei and prevent agglomeration, provided that ultrasound was enabled until complete desupersaturation at the seeding temperature. FTIR and FBRM can be used to determine this end point. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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Review

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20 pages, 13880 KiB  
Review
The Effects of Ultrasound on Crystals: Sonocrystallization and Sonofragmentation
by Hyo Na Kim and Kenneth S. Suslick
Crystals 2018, 8(7), 280; https://doi.org/10.3390/cryst8070280 - 4 Jul 2018
Cited by 95 | Viewed by 14670
Abstract
When ultrasound is applied to a solution for crystallization, it can affect the properties of the crystalline products significantly. Ultrasonic irradiation decreases the induction time and metastable zone and increases the nucleation rate. Due to these effects, it generally yields smaller crystals with [...] Read more.
When ultrasound is applied to a solution for crystallization, it can affect the properties of the crystalline products significantly. Ultrasonic irradiation decreases the induction time and metastable zone and increases the nucleation rate. Due to these effects, it generally yields smaller crystals with a narrower size distribution when compared with conventional crystallizations. Also, ultrasonic irradiation can cause fragmentation of existing crystals which is caused by crystal collisions or sonofragmentation. The effect of various experimental parameters and empirical products of sonocrystallization have been reported, but the mechanisms of sonocrystallization and sonofragmentation have not been confirmed clearly. In this review, we build upon previous studies and highlight the effects of ultrasound on the crystallization of organic molecules. In addition, recent work on sonofragmentation of molecular and ionic crystals is discussed. Full article
(This article belongs to the Special Issue Advances in Ultrasound Stimulated Crystallization)
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