Influence of Crystallization Conditions

As already stated, the crystallization conditions have a significant influence on the product purity achieved. For example, the crystallization conditions that control the growth rate particularly affect the content of impurities originating from liquid inclusions and lattice incorporation. 

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Sallovey, R., and A. Keller The influence of crystallization conditions on radiation effects in polyethylene. Bell System Tech. J. 40, 1397 — 1419 (1961). 

Inui et al. have investigated the influence of crystallization conditions of ZSM-34 zeolite on the attainment of a selective catalyst for olefin formation. They found that an optimum selectivity was obtained with a zeolite ZSM-34 crystallized for 25 to 30 days at 100 C. For shorter crystallization times, the principal product was dimethyl ether. For longer times paraffin selectivity increased, while olefin selectivity decreased. When the precursor was kept at 100 C for only 3 days and then heated to 190 C for 30 min, the resulting catalyst exhibited a better selectivity than zeolites prepared by standard methods. In this case, the conversion of methanol was about 96.9% and about 67.8% was... 

Crystallization also is employed as an intermediate purification step in many processes because of good separation factors per stage and its effectiveness at low temperatures for thermally labile compounds. Particle size and habit are important in these steps as well because of their effect on filtration or centrifugation rates. The influence of crystallization conditions on morphology and PSD, and, therefore, on the de-liquoring characteristics is often overlooked when laboratory work is conducted. However, this becomes much more important in pilot- or full-scale manufacturing where slow de-liquoring can result in low productivity and reduced stability. 

Greco, R. and Ragosta, G. (1988) Isotactic polypropylenes of different molecular characteristics Influence of crystallization conditions and annealing on the fracture behaviour, /. Mat. Sci., 23, 4171-4180. 

Pavlov KA, Dmitrevskii BA (2003) Influence of crystallization conditions in production of citric acid on the properties of forming calcium sulfate. Russ J Appl Chem 76 1408-1413 Furukawa M, Tokunda S (2004) Extraction of heavy metals from a contaminated soil using citrate-enhancing extraction by pH control and ultrasonic application. J Environ Sci Health A... 

Surfaces of cadmium with various morphological properties were electro-formed on the Cd electrode from sulfate solutions by varying current densities, temperature, and pulse electrolysis conditions [218]. The surface properties were defined by the values of slopes of quasi-steady state E versus logarithm current density dependencies and exchange current densities in 0.5 M CdS04 + 0.15 M H2SO4 solution. The dependence of the slope values on surface properties was explained in terms of the influence of crystallization overpotential. 

Bruneton, E., and Colomban, P, Influence of hydrolysis conditions on crystallization, phase transitions and sintering of zirconias prepared by alkoxide hydrolysis, J. Non-Crystl. Solids, 147, 201, 1992. 

A.M. Kulkami, C.F. Zukoski, Nanoparticle crystal nucleation influence of solution conditions, Langmuir 18 (2002) 3090-3099. 

The reactions of many coordination compounds in solution are well documented [1,2]. Comparisons of chemical processes occurring under homogeneous and heterogeneous conditions have potential value in determining the factors which control the reactivities of free ions and the influences of crystal structure on thermal stability. 

Yan, H. Blanford, C.F. Lytle, J.C. Carter, C.B. Smyrl, W.H. Stein, A. Influence of processing conditions on structures of 3D ordered macro-porous metals prepared by colloidal crystal tern-plating. Chem. Mater. 2001, 13, 4314-4321. 

The physical properties of the crystallized APT can be influenced by crystallization conditions to some extent. They are of importance for the further processing to metal powder by hydrogen reduction. 

Ghadiri, M., Yuregir, K.R., Pollock, H.M., Ross, J.D.J., and Rolfe, N. 1991. Influence of processing conditions on attrition of NaCl crystals. Powder Technol 65, 311-320. 

With the use of the Burton-Slichter-Prim model, the influence of crystallizer operating conditions on the amount of substitutional impurity uptake can be assessed. Namely, for values of K less than unity, the quality of separation tends to improve with lower growth rate, increasing diffusivity of the impurity, and decreasing diffusion film thickness. Thus, stronger convection (which reduces the boundary layer thickness 6) is expected to improve separation in these cases (Rosenberger 1986). 

A semibatch reaction crystallizer with a profiled bottom and/ or a draft tube was used by Stavek et al. (1988) to study the influence of hydrodynamic conditions on the controlled doublejet precipitation of silver chloride microcrystals. The crystallizer is a cylindrical vessel (14cm in diameter) equipped with four radial baffles and a six-pitched-blade impeller to provide good mixing. Silver nitrate and potassium chloride solutions were added at a constant rate to the crystallizer, which contained aqueous gelatin solution. The temperature and silver ion concentration in the crystallizer were controlled during the run. 

Centurione, S.L., and Tonhi, M., "The Influence of Burning Conditions on Alite Crystal Characteristics," Proceedings of the 17 th International Conference on Cement Microscopy, International Cement Microscopy Association, Calgary, Alberta, 1995, pp. 232-241. 

DESCRIPTION OF AN INNOVATIVE GC METHOD TO ASSESS THE INFLUENCE OF CRYSTAL TEXTURE AND DRYING CONDITIONS ON RESIDUAL SOLVENT CONTENT IN PHARMACEUTICAL PRODUCTS... 

Application Influence of crystal texture and drying conditions on RS content... 

KuUcami, A. M. and C. F. Zukoski. 2002. Nanoparticle crystal nucleation Influence of solution conditions. Langmuir. 18, 3090. 

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