Crystallization of potash alum: effect of power ultrasound

Abstract

The influence of power ultrasound on the crystallization of potash alum was investigated. Experiments have been carried out in a batch stirred vessel. It was found that ultrasonic waves decrease the supersaturation limits and modify the morphology of the crystals produced. The average crystal size decreases with an increase of ultrasonic power. To investigate also the action of ultrasound on already existing crystals, crystals produced in silent conditions were suspended in saturated potash alum solution at various ultrasonic powers. The results show that ultrasound has also an abrasive effect on potash alum crystals for high power inputs.

The Effect of Ultrasound on the Crystallisation of Paracetamol in the Presence of Structurally Similar Impurities

“…Ultrasound can also increase the rate of secondary nucleation, this is manifested as a reduction on the product crystal size distribution [20,22,24,31,32,[34][35][36][37][38][39][40][41][42][43]. Ultrasound can also influence crystal growth [20,25,26,36,40,[44][45][46] although the effect on crystal growth is not as dramatic as on nucleation and arises largely from enhanced mass transfer [46] and can influence crystal morphology. Other reported outcomes of ultrasonic intervention include influencing; which polymorph nucleates [23,47,48], crystal structure [30], crystal properties [49] and reaction crystallisation [45].…”

The effect of ultrasound on the homogeneous nucleation of BaSO4 during reactive crystallization

“…In the last decade, sonocrystallization has received much attention. The ultrasonic effect on crystallization has been reported to accelerate crystal precipitation (Nishida, 2004;Ichitsubo et al, 2004), retard precipitation (Dalas, 2001), change the crystal size distribution and crystal habit (Lee et al, 2001;Amara et al, 2001;Li et al, 2003;Guo et al, 2005), change crystal character (Enomoto et al, 1996), increase nucleation rate (Teipel et al, 2002;Lyczko et al, 2002;Chow et al, 2003Chow et al, , 2004, depress agglomeration (Kim et al, 2002;Guo et al, 2005) and agglomerate particles (Kusters et al, 1993;Enomoto et al, 1997).…”

Sonocrystallization and Its Application in Food and Bioprocessing

“…Thus, in industrial crystallization processes, ultrasound can induce nucleation in conditions where spontaneous primary nucleation cannot occur without ultrasound. Amara et al (2001) investigated the effect of ultrasonic power dissipation on the crystallization of potash alum in an ultrasonic reactor operating at 20 kHz frequency and variable power dissipation in the range of 10-300 W. Homogenization of the solution was also ensured by external agitation using a propeller rotating at a speed of 1,000 rpm. It has been reported that ultrasound decreases the limit of supersaturation as the nucleation temperature increases due to the presence of ultrasound.…”