THE EFFECT OF VARIOUS FACTORS UPON THE VELOCITY OF CRYSTALLIZATION OF SUBSTANCES FROM SOLUTION^1,2

Abstract

This investigation is an attempt to determine the effect of a number of factors upon the velocity of crystallization (V. C.) of substances from supersaturated solutions in the hope that the results will throw some light upon the mechanism of this very important phenomenon.The question of the order of reaction of the crystallization process has provoked considerable discussion. The equation of Noyes and Whitney3,4 for the velocity of solution of crystals in a solvent of the first order is 57where K is the so-called velocity constant, 5 is the surface area of the crystal or crystals, Cs is the concentration of the saturated solution, and C is the concentration of the solution at any time t. If the processes of solution 1 The work included in this paper is from the thesis presented by John D, Jenkins in partial fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Wisconsin. This investigation was conducted under the supervision of Professor J. H. Walton.

Growth kinetics of ammonium nitrate crystals in a draft tube baffled agitated batch crystallizer.

“…Again in general the agreement between the two techniques is good at higher levels of supersaturation. Also included in Figure 6 for comparison is the kinetic relation of Jenkins (1925) reported by Miller and Saeman (1947). Although the technique employed by Jenkins (1925) is primitive, it does give comparable growth kinetics with those observed in the present study.…”

“…Also included in Figure 6 for comparison is the kinetic relation of Jenkins (1925) reported by Miller and Saeman (1947). Although the technique employed by Jenkins (1925) is primitive, it does give comparable growth kinetics with those observed in the present study. Diffusional mass transfer coefficient as predicted by the correlation suggested by Nienow (1975) for the present configuration and system using L = 7.50 X 10" m and N = 600 rev/min was used to calculate the diffusional mass transfer rates which are also plotted in Figure 6.…”

“…Although several methods are available commercially for its production, the processes for crystallizing ammonium nitrate from its solution have favorable economics and product quality and reduce the explosion hazards to a minimum (Saeman et al, 1952;Miller andSaeman, 1947, 1948). Relatively very little information regarding its crystallization kinetics is available in the literature (Jenkins, 1925;Miller and Saeman, 1947).…”

Microscopic Identification of Certain Sugars and Polyhydric Alcohols

“…Identification of the individual crystals in the mixtures can be made by inspecting the photomicrographs of the previous contribution (23). The influence of the viscosity of the medium is the subject of conflicting opinions {5, 16,18,19). The authors have crystallized glucose from saturated aqueous solutions with six additional miscible solvents of varying viscosity as a preliminary step in the determination of the influence of this factor in the crystallization of sugars.…”

A Molecular Dynamics Study of Solvent and Impurity Interaction on the Crystal Habit Surfaces of ε-Caprolactam

“…Such heterospecies can result in crystal habit modification due to the “impurity” molecules binding to different degrees on the crystallographic surfaces { hkl }. Such effects have long been observed − and have been related to growth solution thermodynamics, − face-specific crystal growth mechanisms, molecular recognition processes at specific habit planes, structural polymorphism, , and solution structuring at the growth interface. , While our understanding of solvent and impurity-mediated crystal growth processes is quite extensive, there is an important fundamental and technological need for the development of routine modeling tools for predicting the mediation of crystal shape by growth environmental factors, such as the growth solvent.…”