Sono-crystallization of ZnSO4⋅7H2O with variation of solution heights

Hassen Harzali,Fabien Baillon,Olivier Louisnard,Fabienne Espitalier,Arbi Mgaidi

doi:10.1016/j.cej.2012.04.087

Hassen Harzali, Fabien Baillon + Show 3 more

Open Access

https://doi.org/10.1016/j.cej.2012.04.087

Copy DOI

Abstract

The effects of acoustic cavitation on crystallization of zinc sulphate heptahydrate was observed in a sono-reactor build-up from a large emitting area transducer located at the bottom of the vessel (sometimes referred as cup-horn reactor).The aim of this work is to carry out measurements of both dissipated acoustic power in the sono-reactor using calorimetric method, and induction time of crystallization of ZnSO4⋅7H2O. Our measurements were recorded in the sono-reactor for different liquid phase heights ranging between 0.08 and 0.2m, and for different electric power supplied by the generator.The experimental results have shown that the dissipated acoustic power passes through a maximum at about 0.15±0.01m, and that the induction time passes through a minimum for the same liquid-level. The dissipated-power and the induction time are found to be well correlated as the liquid height was varied. The acoustics of the sono-reactor was studied with linear acoustics, accounting for the wall vibrations by using the Multiphysics Modelling and Simulation Software (COMSOL). Theoretical dissipated acoustic powers were compared to the experimental ones. One of the motivations of this study is to assess by simulation the existence of the maximum of dissipated power in a given sono-reactor.

Highlights

IntroductionWhen a liquid is irradiated by a high-power ultrasonic wave, numerous radially oscillating micron-sized bubbles appear
The ultrasound science and technology are becoming a growing research field [1] because of a wide range of emerging applications in chemical synthesis, therapeutics, environmental protection, electrochemistry, processing of food, processing of solids and liquids [2].When a liquid is irradiated by a high-power ultrasonic wave, numerous radially oscillating micron-sized bubbles appear
We can neglect the agitation power in the presence of the dissipated power caused by ultrasound

Summary

Introduction

When a liquid is irradiated by a high-power ultrasonic wave, numerous radially oscillating micron-sized bubbles appear. The phenomenon is known as acoustic cavitation [3, 4]. The strong collapse, following the explosive expansion of these bubbles, induces extreme conditions inside or near the bubbles, which are responsible for a specific chemistry, known as sonochemistry. The bubbles repeat expansion and contraction according to the pressure oscillation of an ultrasonic wave [5]. Some bubbles collapse violently at the contraction phase of an ultrasonic wave [3, 6]. The temperature and the pressure inside bubbles increase to 5000 K and 300 atm, respectively or more at the strong collapse [7]

Objectives

Methods

Results

Conclusion