ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Impact of dissolved rare gases (Ar, Xe and He) on single-bubble sonochemistry in the presence of carbon tetrachloride

Aissa Dehane and Slimane Merouani

Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Annaba University, Annaba, Algeria

E-mail: s.merouani@yahoo.fr

Received: 22 July 2021  Accepted: 11 December 2021

Abstract:

In sonochemistry, pyrolysis of CCl₄ inside an acoustic bubble plays various roles (e.g., removing CCl₄, producing reactive chlorine species, speeding ^•OH radical generation, and enhancing water-contaminant destruction). The kind of gas saturating the reaction media is critical in regulating CCl₄ sono-pyrolysis and its outcomes.

The effect of three saturating noble gases (Ar, Xe, and He) on single-bubble sonochemistry in the presence of CCl₄ was numerically studied in this work for a variety of operational circumstances. First, it was discovered that the presence of CCl₄ affects the chemistry of the collapsing bubble, where other chemical processes, including the breakdown of CCl₄ and the formation of reactive chlorine species (RCS: CCl₃, :CCl₂, ^•Cl, Cl₂, HOCl), were accounted. For both total oxidants production (i.e., reactive oxygen and chlorine species) and CCl₄ conversion yields, numerical simulations indicated that the xenon effect outperformed helium and argon. For all operational circumstances, the maximum rate of oxidant production and CCl₄ conversion is in the order Xe > Ar > He. However, the difference in total oxidants generation rates between xenon and argon bubbles is minor than between argon and helium bubbles. Furthermore, the gas type impact was highly dependent on the frequency, the acoustic power, the concentration of CCl₄ and the liquid temperature. The maximal conversion yields were achieved for xenon and argon gases. For maximum oxidants production, a temperature of 40 °C was found to be optimum. The use of high concentrations of CCl₄ (≥ 1 mM), particularly in the presence of xenon, allows maximum oxidants production, which is very advantageous for the use of CCl₄ as intensification technology for the sonochemical removal of hydrophilic pollutants from water.

Keywords: Ultrasound; Saturation gases; Carbon tetrachloride; Sonoactivity; Active bubbles

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-02022-x

Chemical Papers 76 (5) 3011–3030 (2022)