Gas−Liquid Mass Transfer Studies in Sonochemical Reactors

Abstract

In the present work, quantification of the overall gas−liquid mass-transfer coefficient (K L a) in the sonochemical reactors (two different types viz. ultrasonic horn and ultrasonic bath) has been done using the dynamic method. The effect of operating parameters such as the power density into the system, gas flow rate, position of the sparger relative to the ultrasound source, and the presence of sodium chloride (as an electrolyte) on the mass-transfer coefficient has been investigated. Correlations have been developed for the prediction of the volumetric mass-transfer coefficient for liquids in both types of ultrasonic reactors. The information obtained in the present work should be useful in understanding the role of gas−liquid mass transfer in a gas−liquid reaction system using ultrasound as a source of the supply of the energy and should be a breakthrough in the design procedure as no studies of this kind are currently available in the open literature.

A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification

“…4,57,59,60 There are two possible reasons. 4,16,58,59 Conclusion A robust USMR vibrating as a half wavelength resonator was designed and fabricated, according to one dimension design theory, numerical simulation and impedance analysis. Secondly, the intensification mechanism in our USMR-non-inertial cavitation with fierce surface wave oscillation and microstreaming-is more stable and uniformly distributed than in conventional reactors.…”

“…55 However, the improvement of mass transfer in microreactors is mainly due to the large specific surface area. 4,[57][58][59][60] In this paper, the microreactor is combined with ultrasound to intensify gas-liquid mass transfer. [51][52][53] For some reactions of faster kinetics, the mass transfer needs to be further intensified.…”

20kHz sonoelectrochemical degradation of perchloroethylene in sodium sulfate aqueous media: Influence of the operational variables in batch mode

“…We point out this fact because some authors have reported the addition of an electrolyte for the enhancement of the sonochemical treatment of pollutants [48][49][50] and, therefore, a possible contribution from this must, in principle, be considered. Seymour and Gupta [48] reported enhancements of reaction rates (6-fold for chlorobenzene, 7-fold for p-ethylphenol and 3-fold for phenol oxidation), which are proportional to the diethyl ether-water partitioning coefficient of the pollutants.…”

“…The surface tension affects the nucleation process [51] and the cavitational threshold. Other effects ascribed to the presence of electrolyte are the decrease in the gas solubility, its non-coalescing action [49] and persistence of the bubbles after insonication [50]. With this wide scenario, the disentangling of the benefits from application of the electrical field and from the presence of the background electrolyte merits a deeper analysis in further work.…”

Increasing unsaturated dissolved oxygen concentration in water by fine bubbles induced by ultrasonic vibrations

“…In this method, fine dispersion increases the mass transfer rate and reduces the time to reach saturation [20][21][22]. Air was used as the gas to be dissolved and water was used as the solvent.…”