Particle Breakage Kinetics and Mechanisms in Attrition-Enhanced Deracemization

Xiouras, Christos; Fytopoulos, Antonios A.; Horst, Joop H. ter; Boudouvis, Andreas G.; Gerven, Tom Van; Stefanidis, Georgios D.

doi:10.1021/acs.cgd.8b00201

Cited by 33 publications

(40 citation statements)

References 59 publications

(147 reference statements)

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“…This Kapur function analysis showed that stable cavitation bubbles mostly break via fracturing while relative more abrasion was present when transient bubbles were created. Using a similar setup to the previous study, Xiouras et al also studied quantitatively the ultrasound breakage behavior of NaClO3 particles suspended in the antisolvent hexane at a frequency of 41 kHz and 30W (absorbed electrical power) and compared the breakage behavior with that using bead grinding [120]. It was found that for the specific compound, ultrasound led to abrasion, generating many fine particles, while bead grinding caused mostly fracture of the crystals.…”

Section: 5fragmentation / Deagglomeration 251 Observations On Ultrasound Assisted Fragmentation / Deagglomerationmentioning

confidence: 94%

Sonocrystallisation: Observations, theories and guidelines

Jordens

Gielen

Xiouras

et al. 2019

Chemical Engineering and Processing - Process Intensification

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Crystallization is an important and widely used separation technique in the chemical and pharmaceutical industry. Control of the final particle properties is of great importance for these industries. The application of ultrasound in these crystallization processes, also referred to as sonocrystallization, has shown to impact nucleation, crystal growth and fragmentation. As a result this technology has potential to control the final particle size, shape and polymorphic form.This review provides a comprehensive overview of the recent advances in sonocrystallization. It reviews the observed effects of ultrasound on the different stages of the crystallization process. Recent insights in the mechanism behind these effects are discussed as well. Finally, guidelines for the operating conditions, such as ultrasonic frequency, power, type of cavitation bubbles, time window and moment of application are formulated.

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Section: 5fragmentation / Deagglomeration 251 Observations On Ultrasound Assisted Fragmentation / Deagglomerationmentioning

confidence: 94%

Sonocrystallisation: Observations, theories and guidelines

Jordens

Gielen

Xiouras

et al. 2019

Chemical Engineering and Processing - Process Intensification

Self Cite

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“…In addition, recently many emerging technologies have also been developed to achieve this goal. Crystallisation of a racemic mixture is an effective approach to enrich one enantiomer by the formation of conglomerate crystals 24 , 25 or through spontaneous deracemization during crystallisation 26 , 27 . Futhermore, coherent laser light 28 and highly enantioselective enzymes 29 have been used for efficient deracemization.…”

Section: Introductionmentioning

confidence: 99%

Amplification of enantiomeric excess by dynamic inversion of enantiomers in deracemization of Au38 clusters

2020

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Symmetry breaking and amplification processes have likely played a fundamental role in the development of homochirality on earth. Such processes have not been much studied for inorganic matter at the nanoscale. Here, we show that the balance between left- and right-handed intrinsically chiral metal clusters can be broken by adsorbing a small amount of a chiral molecule in its ligand shell. We studied the amplification of enantiomeric excess of the Au38(2-PET)24 cluster (2-PET = 2-phenylethylthiolate). By exchanging a small fraction of the achiral 2-PET ligand by chiral R-1,1′-binaphthyl-2,2′-dithiol (R-BINAS), a mixture of species is obtained composed of anticlockwise (A) and clockwise (C) versions of Au38(2-PET)24 and Au38(2-PET)22(R-BINAS)1. At 70 °C, the system evolves towards the anticlockwise clusters at the expense of the clockwise antipode. It is shown that the interplay between the diastereospecific ligand exchange, which introduces selectivity but does not change the A/C ratio, and the fast racemization of the Au38(2-PET)24 is at the origin of this observation.

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“…Numerous groups report the positive impact of ultrasound, including significantly reducing the induction time [18] , [19] , [20] , [21] , [22] , [23] , reducing the metastable zone width (MSZW) [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] and improving the rate of formation of new nuclei [27] , [28] . In addition, ultrasound has been shown to control final crystal properties such as the crystal size distribution [29] , [30] , [31] , [32] , [33] , [34] , [35] , crystal polymorphism [34] , [36] , [37] , [38] and crystal chirality [39] , [40] , [41] , [42] , [43] – all of which are very important to control, particularly in the pharmaceutical and food industries. Given the complexity of ultrasonic cavitation and traditional crystallisation and the various factors that impact both processes, and despite a significant body of research investigating ultrasound’s effect on the crystallisation process, the detailed mechanisms involved remain elusive.…”

Section: Introductionmentioning

confidence: 99%