Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Influence of Fluid Shear on Primary  Nucleation of Organic Compounds in Solution  Jin Liu  Doctoral Thesis
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. (Transport Phenomena)ORCID iD: 0000-0002-2351-9636
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this work, three experimental systems have been used to study the influence of agitation/ fluid shear on primary nucleation. Three organic compounds have been used with different solvents, i.e. butyl paraben in ethanol solution, curcumin in ethanol solution and m-hydroxybenzoic acid in 1-propanol solution. Induction time and polymorphic outcome were investigated through around 3500 cooling crystallization experiments under different supersaturations and temperatures. It is clearly shown that induction time is influenced by agitation. In the first set of experiments, a large number of experiments have been done in capped vials stirred with magnetic stir bars. It was found that the induction time decreases with increasing agitation rate in the low agitation region. However, further increase in agitation leads to an increase again in the induction time, which is attributed to the irregular rotating behavior of the stir bar at higher rotation rate. In the second set of experiments, relatively uniform shear rate has been generated using a Taylor-Couette flow device. The induction time is found to be inversely related to the fluid shear rate. By fitting the parameters of the classical nucleation theory to experimental data, it is shown that the results can be explained as an influence on the pre-exponential factor while the critical free energy of nucleation is independent of the rotation rate as expected. In the third set of experiments, the influence of agitation conditions on nucleation have been investigated in three parallel jacketed, agitated crystallizers equipped with different types of overhead agitators. Several parameters, including agitation rate, impeller type and size, impeller to bottom clearance and the presence of baffles have been studied. Across all experiments with different fluid mechanics in Taylor-Couette flow device and jacketed crystallizer for the butyl paraben system the induction time is correlated to the energy dissipation rate raised to power 0.3. Through a comprehensive review of literature and analysis based on our experimental results, the shear enhanced pre-nucleation clusters coalescence is identified as the most plausible mechanism. 

The polymorphic outcome in nucleation experiments of m-hydroxybenzoic acid is also influenced by agitation, especially at low driving force of nucleation. In the vial experiments, the proportion of form I decreases at intermediate agitation rates (200 and 400 rpm), where the induction time of form II is more reduced compared to form I. In both Taylor-Couette and jacketed crystallizer experiments, form I is obtained in most experiments at low agitation rate (100 rpm) while form II is obtained in most experiments at higher agitation rates (≥300 rpm). The results are explained by comparing the molecular packing and hydrogen bonding in the structures of both polymorphs. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , 90 p.
Series
TRITA-CHE-Report, ISSN 1654-1081
Keyword [en]
Agitation, Primary nucleation, Induction time, Fluid shear, Energy dissipation, Mass transfer, Molecular alignment, Cluster coalescence, Butyl paraben, Curcumin, m-Hydroxybenzoic acid, Solid-liquid interfacial energy, Nuclei critical radius.
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-155747ISBN: 978-91-7595-327-4 (print)OAI: oai:DiVA.org:kth-155747DiVA: diva2:762565
Public defence
2014-12-04, K1, Teknikringen 56, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20141114

Available from: 2014-11-14 Created: 2014-11-12 Last updated: 2014-11-14Bibliographically approved
List of papers
1. Influence of agitation and fluid shear on primary nucleation in solution
Open this publication in new window or tab >>Influence of agitation and fluid shear on primary nucleation in solution
2013 (English)In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 13, no 10, 4385-4394 p.Article in journal (Refereed) Published
Abstract [en]

The influence of mechanical energy on primary nucleation of butyl paraben has been investigated through 1320 cooling crystallization experiments. The induction time has been measured at different supersaturations, temperatures, and levels of mechanical energy input, in two different flow systems. There is an overall tendency in the experiments that primary nucleation is promoted by increased input of mechanical energy. In small vials agitated by magnetic stir bars, the induction time was found to decrease with increasing agitation power input raised to 0.2 in the low agitation region. However, further increase in agitation leads to an increase again in the induction time. In a concentric cylinder apparatus of Taylor-Couette flow type, the induction time is inversely related to the shear rate. By fitting the parameters of the classical nucleation theory to experimental data, it is shown that the results can be explained as an influence on the pre-exponential factor. The treatment behind the pre-exponential factor is extended to account for the contribution of forced convection in a solution exposed to agitation and fluid shear. However, the analysis cannot verify that increased rate of mass transfer can explain the results. Alternative mechanisms are discussed based on a comprehensive review of the relevant literature. Shear-induced molecular alignment and in particular agitation-enhanced cluster aggregation are mechanisms that appear to deserve further attention.

Keyword
Classical nucleation theory, Cluster aggregation, Concentric cylinders, Cooling crystallization, Magnetic stir bars, Mechanical energies, Preexponential factor, Taylor Couette flow
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-133176 (URN)10.1021/cg4007636 (DOI)000326300200035 ()2-s2.0-84885130886 (Scopus ID)
Note

QC 20131028

Available from: 2013-10-28 Created: 2013-10-28 Last updated: 2017-12-06Bibliographically approved

Open Access in DiVA

No full text

Authority records BETA

Liu, Jin

Search in DiVA

By author/editor
Liu, Jin
By organisation
Transport Phenomena
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 319 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf