Anomalies detected during hydrodynamic cavitation when using salicylic acid dosimetry to measure radical production

Zupanc, Mojca (author), Petkovšek, Martin (author), Zevnik, Jure (author), Kozmus, Gregor (author), Šmid, Alenka (author), Dular, Matevž (author)

Cavitation used to be associated with negative outcomes in hydraulic turbomachinery but nowadays it is often used for water cleaning, microorganism’s destruction and degradation of organic compounds. This study investigated the amount of ·OH formed during hydrodynamic cavitation using salicylic acid dosimetry. The radical’s amount was evaluated by quantifying the concentration of 2,3-dihydroxybenzoic acid, catechol and 2,5-dihydroxybenzoic acid. Two concentrations of the dosimeter in tap water were investigated, 50 and 300 mg L$^{−1}$ (pH approx. 2.5). After 90 min of cavitation using a Venturi constriction a sum of the three products was determined at 0.97 µg mL$^{−1}$ and 1.81 µg mL$^{−1}$, respectively. However, during the investigation the anomalies were detected in the cavitation development when higher concentration of salicylic acid was used – cavitation appeared more gentle, with less intense collapses, unrelated to the one in pure water. Detailed observations of cavitation and additional bubble dynamics simulations revealed that the decreased surface tension of the acidified salicylic acid solution is the most influential physical characteristic. Further experiments on nucleation and coalescence showed that high concentration of salicylic acid also leads to longer stability of the bubbles and prevents their coalescence due to short-range repulsive forces (steric hindrance), which results in less violent bubble collapse. We also discuss the importance of an appropriate amount of the dosimeter for correct evaluation of ·OH production in a given cavitation device (50 mg L$^{−1}$ for the present one). This is essential for further cavitation exploitation studies to avoid false interpretation of the gathered results.

• Language: English
• Keywords: cavitation, nucleation, coalescence, salicylic acid dosimetry, anomalies, physical characteristics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering; FFA - Faculty of Pharmacy
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: 11 str.
• Numbering: Vol. 396, art. 125389
• PID: 20.500.12556/RUL-116143
• UDC: 532.528(045)
• ISSN on article: 1385-8947
• DOI: 10.1016/j.cej.2020.125389
• COBISS.SI-ID: 15039491
• Publication date in RUL: 18.05.2020

Record is a part of a journal

• Title: Chemical engineering journal
• Shortened title: Chem. eng. j.
• Publisher: Elsevier
• ISSN: 1385-8947
• COBISS.SI-ID: 2110998

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: kavitacija, nukleacija, koalescenca, dozimetrija salicilne kisline, anomalije, fizikalne lastnosti