Effect of ultrasound on the heterogeneous nucleation of BaSO4 during reactive crystallization

Abstract

The effect of ultrasound on reactive crystallization is studied by measuring the induction time when nucleation is predominantly heterogeneous. Barium sulphate is used as the working substance precipitated by mixing aqueous BaCl2 and Na2SO4 solutions with relatively low concentrations compared to experiments for homogeneous nucleation. It is observed that at a given supersaturation level, the induction time significantly decreases with increasing ultrasonic energy input. The mechanism of the ultrasonic effect on heterogeneous nucleation is analyzed. The effect of ultrasound is to increase the diffusion coefficient (DAB) while reducing the contact angle (θ) and geometric factor (f). This gives rise to an increase in the heterogeneous nucleation rate and shorter induction time. The ultrasonic effect on critical supersaturation ratio (Scrit) is also investigated to determine the mechanism of ultrasonic effect on f and θ. Both the force from the cavitational bubble implosion and the nucleation process occurring at bubble/solution/foreign solid interface are proposed as the predominant reasons why contact angle (θ) decreases with the increase of energy input.

Sonocrystallisation of sodium chloride particles for inhalation

“…Apart from constituting a rapid application, sonocrystallisation also offers further advantages including smaller crystal size produced compared to conventional crystallisation, cost effectiveness of apparatus, the process can be run at ambient conditions and the reaction vessel involved is of simple geometry making the cleaning process simple for the pharmaceutical requirements. Another important advantage is that because crystal growth occurs at lower supersaturation levels where initial growth is controlled, the size distribution of the products is narrower than uncontrolled crystallisation process (Mullin and Nyvlt, 1971;Guo et al, 2006a).…”

Synthesis of Caffeine/Maleic Acid Co-crystal by Ultrasound-assisted Slurry Co-crystallization

“…Ultrasound application results in a dramatic reduction in induction period, metastable zone width and altered supersaturation conditions. [10][11][12][13] This will have significant effect on co-crystallization process of non-congruent system like caffeine -maleic acid. The sonochemistry reports available to date on co-crystallization of caffeine -maleic acid have used organic solvents.…”

CFD modeling of mixing intensification assisted with ultrasound wave in a T-type microreactor

“…The [I À 3 ] concentration of samples were evaluated by UV spectrophotometer and for each step the segregation index values were calculated using Eqs. (7)(8)(9)(10)(11)(12)(13)(14).…”

“…On the other hand, in many studies the effect of ultrasonic waves on mixing efficiency were investigated [8][9][10][11][12][13][14]. The influence of low-frequency (20 kHz) ultrasonic power of on micromixing in a continuous reactor in aqueous and viscous solutions was studied by Monnier et al [15].…”