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Spherical Crystallization of Benzoic Acid
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Spherical agglomerates of benzoic acid crystals have been successfully prepared by drowning-out crystallization in three solvent partial miscible mixtures. Benzoic acid is dissolved in ethanol, bridging liquid is added and this mixture is fed to the agitated crystallizer containing water. Fine crystals are produced by crystallization of the substance, and the crystals are agglomerated by introduction of an immiscible liquid called the bridging liquid. The concentration of solute, agitation rate, feeding rate, amount of bridging liquid and temperature are found to have a significant influence on the physico-mechanical properties of the product. The product particle characterization includes the particle size distribution, morphology and mechanical strength.

Many of the solvents such as chloroform, toluene, pentane, heptane, cyclo hexane, diethyl ether and ethyl acetate were used as bridging liquids. Among the selected solvents ethyl acetate and di ethyl ether could not form the spherical agglomerates. Characteristics of the particles are changing with the bridging liquid used. Range of the operation for spherical agglomeration is very narrow and was shown that only at certain conditions the spherical agglomerates are produced. Increased amount of bridging liquid, decrease in feeding rate and temperature causes the particle size to increase. Particle morphology depends on the bridging liquid used, amount of bridging liquid and the temperature. Particles look completely spherical from the experiments where toluene is used as bridging liquid.

The mechanical strength of single agglomerates has been determined by compression in a materials testing machine, using a 10N load cell. For single particle compression an approximate estimation of the true stress is presented. Compression characteristics for single agglomerates are compared with data on particle bed compression. Low elastic recovery and high compressibility of the single particles and of bed of particles reveals that the spherical agglomerates prepared in this work have a plastic behavior which is expected to be favorable for direct tabletting. Some of the stress–strain curves are J-shaped with no clear fracturing of the particles, and are well correlated by an exponential–polynomial equation.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , vi, 51 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2007:87
Keyword [en]
Spherical agglomeration, Spherical agglomeration, Benzoic acid, Solubility phase diagram, Physico mechanical properties
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4602ISBN: 978-91-7178-843-6 (print)OAI: oai:DiVA.org:kth-4602DiVA: diva2:13049
Presentation
2008-01-18, D41, KTH, Lindstedtsvägen, Stockholm, 10:10
Opponent
Supervisors
Note
QC 20101119Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2010-11-19Bibliographically approved
List of papers
1. Spherical Crystallization of benzoic acid
Open this publication in new window or tab >>Spherical Crystallization of benzoic acid
2008 (English)In: Internation Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 348, no 1-2, 61-69 p.Article in journal (Refereed) Published
Abstract [en]

This paper deals with the development of a method for spherical crystallization of benzoic acid. Benzoic acid is dissolved in ethanol, water is used as anti-solvent and chloroform is used as bridging liquid. After an introductory screening of different methods, the influence of the amount of the bridging liquid, the solute concentration and the stirring rate is investigated. The product particle characterization includes the particle size distribution, morphology and strength. The mechanical strength of single agglomerates has been determined by compression in a materials testing machine, using a 10 N load cell. It is found that favourable properties are obtained if the bridging liquid is added during the crystallization. Larger and stronger well-shaped agglomerates are formed. The stress-strain curves are J-shaped with no clear fracturing of the particles, and are well correlated by an exponential-polynomial equation.

Keyword
crystallization, spherical agglomeration, benzoic acid, physico-mechanical properties (size distribution, particle morphology, compression strength)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-7885 (URN)10.1016/j.ijpharm.2007.07.006 (DOI)000253036600009 ()2-s2.0-37249086046 (Scopus ID)
Note
Uppdaterad från accepted till published(20101119) QC 20101119Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2011-04-19Bibliographically approved
2. Spherical Crystallization of Benzoic Acid in Ethanol - Water - Toluene
Open this publication in new window or tab >>Spherical Crystallization of Benzoic Acid in Ethanol - Water - Toluene
(English)Article in journal (Other academic) Submitted
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-7886 (URN)
Note
QC 20101119Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2010-11-19Bibliographically approved
3. Evaluation of bridging liquid on spherical crystallization of benzoic acid
Open this publication in new window or tab >>Evaluation of bridging liquid on spherical crystallization of benzoic acid
2008 (English)In: Proc. 17’th International Symposium on Industrial Crystallization / [ed] JP Janssens; J Ulrich, 2008, 369-376 p.Conference paper, Published paper (Other academic)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-7887 (URN)
Conference
17th International Symposium on Industrial Crystallization, ISIC17. Maastricht, The Netherlands. Sep 14-17 2008
Note
QC 20120509Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2012-05-09Bibliographically approved

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