Chemical Engineering & Technology

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Special Issue: Industrial Crystallization

February, 2006

Volume 29, Issue 2

Pages 157–285

    1. Industrial Crystallization (pages 165–166)

      M. Kind and J. Ulrich

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200690004

    2. Validation of a Model for Multiple Agglomeration (pages 171–174)

      A. Cameirão, F. Espitalier, R. David and L. Rouleau

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500367

      The agglomeration process during crystallization is far from being completely understood. A two-step agglomeration model is developed for the crystallization of a zeolite. It accounts for the crystallization of crystallites from the amorphous phase and the subsequent growth and agglomeration processes. When porosity of the secondary agglomerates is introduced into the model, the agreement with experimental data is largely improved.

    3. Towards a Crystalline Product Quality Prediction Method by Combining Process Modeling and Molecular Simulations (pages 175–181)

      J. H. ter Horst, H. J. M. Kramer and P. J. Jansens

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500379

      It is shown for the first time that a combination of molecular simulations and process modeling can be used to predict crystalline product quality aspects such as the polymorphic fraction and crystal size distribution. Furthermore, a deeper understanding of polymorph crystallization can be obtained by combining research on a molecular scale with that on a process scale.

    4. Thermodynamic Predictions of Physical Properties – Prediction of Solid Solutions in Molecular Solutes Exhibiting Polymorphism (pages 182–186)

      G. Coquerel

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500377

      The lattice energies of the different polymorphic varieties are normally close. It is shown that solid solutions, by means of insertion or substitution, can substantially modify the energy landscape between polymorphs. Fluctuations in the transition temperatures lead to the prediction of the existence of solid solutions.

    5. Seeding during Batch Cooling Crystallization – An Initial Approach to Heuristic Rules (pages 187–190)

      A. Warstat and J. Ulrich

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500372

      The use of a combination of a seeding technique and a controlled cooling profile improves the crystal size distribution and crystal purity (reduces mother liquor inclusions within the crystals). General rules are extracted for the dependence of seeding procedures on material properties, which are presented in the form of heuristic rules with the aim of providing guidelines on how to improve product quality by using a seeding technique.

    6. Effect of Fluid Dynamics on Particle Size Distribution in Particulate Processes (pages 191–199)

      D. L. Marchisio, M. Soos, J. Sefcik, M. Morbidelli, A. A. Barresi and G. Baldi

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500358

      The shear devices Taylor-Couette cell and stirred tank are taken as models for aggregation and breakage processes in crystallization and precipiation. When aggregation and breakage processes are much slower than mixing a simplified homogeneous model can be used whereas when they occur on a time-scale comparable with that of mixing then a detailed approach based on computational fluid dynamics (CFD) is needed. For a very high concentration the presence of the solid phase is not neglectible and a multi-phase model must be used.

    7. Determination of Operating Conditions for Controlled Batch Cooling Crystallization (pages 200–205)

      G. Yang, M. Louhi-Kultanen, Z. Sha and J. Kallas

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500351

      To control the supersaturation level during batch processes, a cooling model was introduced which included the seeding condition, cooling rate, batch time, and crystallization kinetics. The cooling profiles were predicted and the mean product sizes were simulated. Based on the simulation results, the relationship between the operating conditions, the supersaturation level, and product size was established.

    8. Utilization of Focused Beam Reflectance Measurement in the Control of Crystal Size Distribution in a Batch Cooled Crystallizer (pages 206–211)

      S. Barthe and R. W. Rousseau

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500364

      Controlling crystal size distribution CSD is important for downstream processing and product quality. The distribution can be characterized by a mean or dominant size and the spread about the mean or dominant size. The development of tools leading to the control of the distribution in a batch crystallizer is the main topic of the present study. Experiments were conducted leading to the implementation of a control scheme for batch cooling crystallization, thus enabling the generation of a predictable mean size and width of the product size distribution.

    9. Strategy to Obtain nm Size Crystals through Precipitation in the Presence of Polyelectrolyte (pages 212–214)

      I. Hirasawa, T. Mikami, A. Katayama and T. Sakuma

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500355

      Crystals of lead sulfate were precipitated in solutions of various polyelectrolyte polymers. Polyetyleneimine (PEI) basic polymer controlled both the nucleation rate and crystal growth rate, and enabled the production of fine monodispersed crystals. Interaction between lead ions and PEI was detected, suggesting that lead ions made some kind of complex with PEI.

    10. Investigation of Precipitation of Calcium Carbonate at High Supersaturations (pages 215–220)

      J. Schlomach, K. Quarch and M. Kind

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500390

      The formation mechanism of precipitated calcium carbonate from aqueous solution under industrial conditions (high supersaturation) was investigated in a semi-batch and in a continuous mixing nozzle process. The influence of potassium hydroxide and magnesium chloride on crystal modification and particle size were investigated in both processes. Rheological properties of the magnesium stabilized amorphous gel structure have been measured.

    11. Raman Spectroscopy – A Powerful Tool for the Quantitative Determination of the Composition of Polymorph Mixtures: Application to CaCO3 Polymorph Mixtures (pages 221–225)

      A. Dandeu, B. Humbert, C. Carteret, H. Muhr, E. Plasari and J. M. Bossoutrot

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500354

      A new Raman spectroscopy method is developed for mixtures containing more than two polymorphs, and tested in the case of vaterite, aragonite, and calcite mixtures of different compositions. It is proven that Raman spectroscopy is a powerful, accurate, and reliable technique for quantitative determination of polymorph mixtures of calcium carbonate.

    12. Partial Miscibility of Organic Compounds in the Solid State – The Case of Two Epimers of a Diastereoisomer (pages 226–232)

      W. Beckmann and H. Lorenz

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500359

      For the the crystallization of two epimers of a diastereoisomer, the formation of partial solid solutions with a respective solubility limited to approximately 5 % and 3 % has been shown using both DSC and XRPD measurements. The enthalpies of fusion of the solids are a strong function of the content of the opposite epimer. This can be interpreted as the disruption of bonds in the lattice.

    13. Polymorphism of Active Pharmaceutical Ingredients (pages 233–237)

      P. H. Karpinski

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500397

      Different polymorphs of the same active pharmaceutical ingredient (API) display distinct physical properties, such as melting point, solubility, dissolution rate, hygroscopicity, stability, etc. The ability to successfully produce and reproduce specific stable polymorphs is intricately correlated with the efficiency and speed of drug development, the robustness of manufacturing process, and – ultimately – the stability and quality of APIs.

    14. Pharmaceutical Compound Crystallization: Growth Mechanism of Needle-Like Crystals (pages 239–246)

      P. Taulelle, J. P. Astier, C. Hoff, G. Pèpe and S. Veesler

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500361

      The structure, morphology, habit, and growth behavior of needle-like crystals of Irbesatan phase A grown from 2-propanol solution are studied. Molecular modeling shows unusually high anisotropy of the internal crystal structure, leading to the prediction of an acicular habit. The crystals are agglomerated with the same crystallographic orientation as the individual constituent; this was explained by regular over- and intergrowths as in the case of twinning.

    15. Adsorption Isotherms of Citric Acid Acting as a Growth-Suppressor onto the (100) and (111) Faces of Sodium Chloride Crystals in Supersaturated Aqueous Solution (pages 247–250)

      S. Sasaki, N. Kubota and N. Doki

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500353

      The growth-starting supercooling ΔTG was measured in supersaturated aqueous solutions in the presence of citric acid as an impurity. It was measured both for the (100) and (111) faces of sodium chloride crystals. This ΔTG method is a convenient method for the determination of adsorption isotherms of an impurity onto specific crystallographic faces of a crystal.

    16. Influence of Crystallization Conditions on Rheology and Microstructure of Dense Suspensions of Crystals of Eflucimibe (pages 251–256)

      S. Teychene, J. M. Autret and B. Biscans

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500374

      To better understand the structural evolution of the suspension during the crystallization process of eflucimibe, a new acylcoenzyme A cholesterol O-acyl-transferease (ACAT) inhibitor, batch cooling crystallization experiments were carried out in a mixture of two solvents, ethanol and n-heptane. The eflucimibe crystal suspensions obtained were successfully characterized by classical techniques and by rheological measurements. The results show that above a critical solid volume fraction, the system moves toward a very structured gel-like network which is a probleme as a brake for the process scale-up.

    17. Precipitation of L-Glutamic Acid: Determination of Nucleation Kinetics (pages 257–264)

      J. Schöll, L. Vicum, M. Müller and M. Mazzotti

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500369

      A new procedure to determine the nucleation kinetics during reactive precipitation to the pH-shift precipitation of L-glutamic has been applied. The induction time has been measured precisely in a stirred batch reactor by the combination of ATR-FTIR spectroscopy and Focused Beam Reflectance Method. The precipitated polymorph is identified using in situ Raman spectroscopy and Particle Volume Monitor. The induction time is used together with the independently measured growth kinetics to determine the nucleation rate.

    18. Prediction of Dextrose Nucleation Kinetics by the Growth Rate of Crystallites (pages 265–270)

      M. Parisi, M. Rivallin and A. Chianese

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500350

      Despite of the great industrial importance of dextrose, very few studies on dextrose monohydrate (DX) crystallization kinetics have been reported in the literature. In particular, there are few experimental works on the measurement of nucleation point and induction time. This work provides experimental data on both the metastable zone width and the induction time of DX in seeded aqueous solutions. However, the main aim is to show how it is possible to predict the nucleation point of DX aqueous solutions on the basis of the growth rate of crystallites.

    19. Purification of Phosphoric Acid from Waste Acid Etchant using Layer Melt Crystallization (pages 271–276)

      K.-J. Kim

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500383

      The recovery of phosphoric acid from waste etchant was conducted using static melt crystallization. The effect of cooling rate, amount of seeds, subcooling, and sweating on the distribution coefficient was investigated. Nitric acid and acetic acid were removed by single-stage layer crystallization, and the quantity of metallic impurities was reduced by a factor of 1000.

    20. Factors Affecting Metal Removal in Mixed Sulfide Precipitation (pages 277–280)

      A. Lewis and A. Swartbooi

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500365

      Sulfide precipitation of nickel and cobalt was investigated in three reactors: batch, seeded fluidized bed with an aqueous sulfide source, and bubble column with a gaseous sulfide source. In terms of metal removal and settling rate, the sulfide system is the most efficient. Metal removals of approximately 90 % were achieved, but the removals decreased with excess sulfide, probably due to the formation of aqueous polysulfide species.

    21. Factors Affecting the Polymorphic Outcome of Glycine Crystals Constrained on Patterned Substrates (pages 281–285)

      A. Y. Lee, I. S. Lee and A. S. Myerson

      Version of Record online: 30 JAN 2006 | DOI: 10.1002/ceat.200500375

      The effect of the solution concentration on the polymorphic outcome of glycine crystals confined to the hydrophilic metallic islands was investigated. The solvent evaporation rate was found to affect the polymorph distribution of glycine; slow evaporation yields α-glycine while fast solvent evaporation favors the high energy phase, β-glycine, due to the creation of high supersaturation.