Long-Time Growth Rate Changes of Sodium Chlorate, Potassium Dihydrogen Phosphate, and Rochelle Salt Crystals Independent of Growth Conditions

Abstract

Results of investigations of the changes in growth rate inherent to crystals (i.e., independent of macroscopic external conditions) during a 15-h growth period are presented. The results of the investigations regarding the time evolution of the growth rate dispersion are also presented. The majority of the investigations were carried out with sodium chlorate crystals, and several experiments were carried out with potassium dihydrogen phosphate (KDP) and Rochelle salt crystals. It was found that, for the majority of the crystals, the main changes in growth rate occurred in the initial growth stage, which extended to for up 4 h. These growth rates probably slowly decrease toward the end of the growth run. Some of the very high initial growth rates that decreased during the initial growth period were followed by relatively high intermediate growth rates for the next few hours and then subsequently decreased. The growth rates for the majority of crystals probably gradually decreased after 15 h of growth. The results obtained show that these changes, which have not previously been taken into account, should be included in the interpretation of growth rate changes affected by various parameters (supersaturation, temperature, fields, stress, impurities, etc.). The obtained results could improve the current crystal growth theories, which are based on the design of specific growth conditions that result in a target product.

Investigation of growth rate dispersion in lactose crystallisation by AFM

“…During experiments, crystals grew at a constant rate and no reduction in growth rate was observed. However, as seed crystals were grown for 24 hours before growth rates were measured, it is not possible to comment if growth rates reduced gradually during earlier stages of growth as suggested by Zekic et al [36].…”

“…The consequence of GRD is an increase in the numbers of small slow growing crystals and therefore a reduction of the mean particle size in both batch and continuous crystallisers [3]. Since then, many other crystals have been reported to exhibit growth rate dispersion, for example potash alum [3] , citric acid [4], fructose [5], sodium chloride [6] and others [7]. It has been reported for crystals generated by both primary and secondary nucleation [8].…”

Influence of a Static Magnetic Field on the ⟨100⟩ Growth Rates of Sodium Chlorate Crystals from Aqueous Solution

“…The experimental setup used for the research is described in detail elsewhere. 11 Nucleation and crystal growth took place in a cell that, for the purposes of these experiments, consisted only of plastic and glass components. The diameter of the cell was 36 mm, the height was 15 mm, and the volume was 15 mL.…”

A comparison of struvite precipitation thermodynamics and kinetics modelling techniques

“…Growth rate dispersion (GRD) is an alternative method of describing growth which has been observed in many crystal systems (Randolph & White 1977;Zekic et al 2011;Ochsenbein et al 2015). This phenomenon has been discussed extensively yet remains to be properly understood (Randolph & Larson 1988;Mullin 2001;Mitrovićet al 2008;Singh & Ramkrishna 2014).…”