Effect of different gases on the sonochemical Cr(VI) reduction in the presence of citric acid

Effects of gas saturation and sparging on sonochemical oxidation activity in open and closed systems, Part I: H2O2 generation

“…Ultrasonic degassing also plays an important role in the removal of gas molecules [11] , [12] , [13] . However, the concentrations of dissolved gases have rarely been monitored, and few researchers have reported the concentrations of dissolved oxygen (DO) before and after ultrasonic irradiation [12] , [14] , [15] , [16] . In some studies, researchers continuously supplied gases throughout ultrasonic irradiation, using a sparger, to maintain the gas content in the liquid phase [4] , [5] , [14] , [17] , [18] , [19] , [20] .…”

“…Recently, there has been growing interest in the on-site generation of H 2 O 2 using various methods to reduce the risk and cost of H 2 O 2 storage, transportation, and use [22] , [23] . Sonochemical methods have proven effective for the generation of H 2 O 2 for decades [7] , [14] , [15] , [24] , [25] , [26] , [27] , [28] . Even though higher generation rate of H 2 O 2 could be obtained in the range of several hundred kilohertz [2] , it was reported that low frequency (20 – 40 kHz) ultrasound could be more appropriate for large-scale sonoreactors [28] , [29] , [30] , [31] .…”

Quantification of sonochemical and sonophysical effects in a 20 kHz probe-type sonoreactor: Enhancing sonophysical effects in heterogeneous systems with milli-sized particles

“…Saturating gases, including Ar and O 2 , can reportedly affect the severity of cavitation by changing the environmental conditions inside the cavitation bubbles [32] , [44] , [45] , [46] . Previous studies have reported the effectiveness of Ar/O 2 gas mixtures for sonochemical oxidation reactions [44] , [45] , [47] .…”

The use of ultrasound in the South Cone region. Advances in organic and inorganic synthesis and in analytical methods

“…In 2020, the same group [65] studied the Cr(VI) reduction in the presence of Cit, using ultrasound energy (850 kHz), under different atmospheres. In all cases, zero-order kinetics was observed, and the complete Cr(VI) reduction to Cr(III)-Cit complexes after 180 min insonation was obtained with the reactor open to air without sparging (ROAWS), and under argon sparging, while a lower Cr(VI) reduction efficiency was achieved under the other conditions (Ar, O 2 , air and N 2 sparging).…”