Phase Transformation of Sulfamerazine Using a Taylor Vortex

Abstract

A Couette–Taylor (CT) crystallizer was used to demonstrate the unique fluid dynamic properties of a Taylor vortex for the phase transformation of sulfamerazine (SMZ). With a conventional Rushton mixing tank (MT) crystallizer, the phase transformation from a metastable crystalline phase to the stable crystalline phase took more than 60 h with acetonitrile (ACN) as the solvent and an agitation rate of 3000 rpm. Using a CT crystallizer, this phase transformation occurred within 3–7 h with rotation speeds in the CT crystallizer of 300–1000 rpm. Increasing the rotation speed of the CT crystallizer also significantly enhanced the phase transformation, whereas adding water to the solvent increased the solubility difference between the two polymorphs and accelerated the phase transformation in both crystallizers. The phase transformation in the CT crystallizer was always many times faster than that in the MT crystallizer. Nucleation and mass-transfer models were used to describe the nucleation induction time of the stable crystal form and the transformation of metastable crystals into stable crystals. The influence of the fluid motions of the periodic Taylor vortex and random eddy in the CT and MT crystallizer, respectively, on the induction time was correlated by the nucleation enhancement factor, which was expressed as function of energy dissipation. The resulting induction and transformation times correlated well with the experimental data in terms of the energy dissipation and solubility difference across the whole range of phase transformation conditions, including rotation speeds, water fractions, and temperatures.

Preparation and photoluminescence properties of uniform LaCO3OH triangular nanoplates

“…Since the different solubilities of these two crystal phases, the orthorhombic nanosheets were gradually dissolved into the synthetic solution and the hexagonal defects acted as the active site for the phase transition, leading to the formation of hexagonal nanoparticles [14,15]. The anisotropic nucleation growth of these nanoparticles yielded the triangular plate-like structure.…”

Application of Taylor Vortex to Crystallization

“…The influence of a Taylor vortex on polymorphic nucleation during phase transformation was recently reported by Lee et al (2011). In this case, metastable crystals (Form-I) of sulfamerazine were suspended in a Taylor vortex for phase transformation via polymorphic nucleation into stable crystals (Form-II).…”

“…The hydrodynamics induced in a Taylor crystallizer are characterized by a periodic vortex motion; whereas, the hydrodynamic fluid motion in an MSMPR crystallizer is a random turbulent eddy. Therefore, in the case of a Taylor (Lee et al, 2011) vortex, the shear and elongation stress from the pair of oppositely rotating vortices align the solute molecules while they move in a radial direction. Such flow-induced nucleation was already observed in the melt spinning of polymers (Zhemayev et al, 2010), where a high shear during melt spinning initiated polymer nucleation, resulting in a high crystalline polymer product.…”

Crystal growth of cholesterol in hydrogels and its characterization

“…From the structural point of view, cholesterol crystals have a monohydrate triclinic structure with a space group P1, having eight-unit-formula per cell, at room temperature with cell parameters a ¼14.172(7) Å, b ¼38.443 (18) Å, c ¼10.481(5) Å, α¼93.88 (4)1, β¼90.67(4)1 and γ¼117.81(4)1. However, cholesterol crystals have also a triclinic anhydrous phase, described also by the space group P1.…”

“…The monohydrate phase shows three reversible endothermic transitions: the first at 86 1C, the second at 123 1C, and the third at 157 1C [17]. The existence of these phase transitions, closely related to polymorphism in different pharmaceutical drugs, is a well-known process [18]. Also isosymmetric phase transitions associated with intergrowths have been demonstrated for some triclinic minerals [19].…”