EXPRESS: Application of High-Frequency Ultrasound and Simultaneous Action of the High- and Low-Frequency Ultrasound in Sonoluminescence Spectroscopy.

Research on sonoluminescence spectroscopy was continued with a focus on determining the content of the main substance in natural underground brines and technological solutions with high salt concentrations (350-1000 g·dm⁻3) using high-frequency ultrasound (44-50 MHz) to initiate sonoluminescence. The influence of the initiating ultrasound frequency on the sonoluminescence intensity of CsCl, LiCl, and NaCl was determined. The maximum sonoluminescence intensity for alkali metal chlorides was achieved at an ultrasound frequency of 48-49 MHz and an intensity of 32 W·cm⁻2.A method for determining Cs, Li, and Na content in highly concentrated technological solutions using high-frequency ultrasound to initiate sonoluminescence was developed. The method's validity was verified by analyzing the same samples using sonoluminescence spectroscopy with low- and mid-frequency ultrasound initiation.The simultaneous effect of high-frequency (45-50 MHz) and low-frequency (18-23 kHz) ultrasound in determining macroimpurities (KCl and LiCl) in NaCl brines using sonoluminescence spectroscopy was studied.When using the simultaneous action of high-frequency (44-50 MHz) and low-frequency ultrasound (18-23 kHz), the lower limit of determination of KCl and LiCl content in brines decreases by 12-15 times compared to the use of ultrahigh and low-frequency ultrasound and amounts to 0.007 and 0.008 g·dm-3, respectively. The best results were obtained with the simultaneous effect of high-frequency ultrasound of 47-48 MHz with an intensity of 29-30 W cm-2 and low-frequency ultrasound of 19-22 kHz with an intensity of 1.3-1.5 W cm-2.