Spontaneous crystallization of potassium chloride from aqueous and aqueous‐ethanol solutions Part 1: Kinetics and mechanism of the crystallization process

Abstract

Kinetics of spontaneous crystallization of potassium chloride from aqueous and aqueous-ethanol solutions were studied. During the crystallization of the salt the electrical conductance and optical transmission of the supersaturated solutions were measured automatically. For monitoring of the total surface of growing potassium chloride crystals at the crystallization the turbidimetric method was used. The growth rate and activation energy of the crystals were determined. The crystal growth rate was proportional to supersaturation. When the volume fraction of ethanol in the solution increased from 0 to 25.76%, the activation energy of the growth process did not change and was about 60 kJ⋅mol -1. Aggregation of the crystals was found. The aggregation kinetics of the crystals may be described approximately by the famous Smoluchowski equation for coagulation of colloidal particles.

Part 1: Kinetics and mechanism of the crystallization process

“…In addition, the effect of ethanol on the kinetic parameters of the growth process also presented some theoretical interest. Earlier similar crystallization of potassium chloride from aqueous and aqueousethanol solutions was studied [7]. So it was interesting to compare those results [7] with the data of the present study.…”

“…The concentration of the salt was found using the electrical conductance of the solution and calibration curves. The laboratory rig was described in details in the previous paper [7].…”

“…It showed that the phase composition didn't change and was NaCl. Further mathematical treatment of the experimental data was done using equations [7]:…”

“…In the mixed mode of the growth process at which neither the kinetic nor the diffusion stages are defining V=V d =V k . Hence, in most simple case of the atomically roughened crystal faces, one can write after transformation [7]: …”

Nacl’ Ün Çekirdeklenme Kinetiğine Ağır Metal Safsızlıklarının Etkisi

“…Sodyum klorür kristalizasyonu safsızlıkların yanı sıra, çözelti inklüzyonu [9], kristalizördeki akış rejimi [10], karıştırma hızı [11] ve ikinci çözücü etkisi [12][13][14] gibi parametrelerdeki değişimlerden etkilenmektedir.…”