Probing the radical chemistry and the reaction zone during the sono-degradation of endocrine disruptor 2-phenoxyethanol in water

Abstract

Sonochemical degradation at 600 kHz of 2-phenoxyethanol (PhE), an endocrine disrupting compound, was performed in the presence of several organic additives, namely: 2-propanol, Triton X-100 and sucrose, of different volatilities to obtain detailed information on the reaction zone and the oxidation pathway of this priority emerging water contaminate. It was found that sonication at 600 kHz and 120 W completely remove PhE (10 mg L) from aerated solutions within 100 min of irradiation. Very little removal of PhE (∼7%) and low accumulation of HO took place in the presence of adequate amount of 2-propanol, indicating that reaction with OH radical outside the bubble is the major degradation pathway of PhE. Addition of the hydrophobic surfactant Triton X-100, as an OH-probe for the interfacial region, at 10 and 100 mM reduced the degradation event by 57% and 72% and resulted in more than 50% decrease in the yield of HO, confirming that PhE degradation occurs mainly at the bubble/solution interface with hydroxyl radical attack. Addition of the hydrophilic substrate glucose at high doses decreased slightly (∼7%) the degradation of PhE and the formation rate of HO, meaning that the bulk of the solution participate marginally in the degradation of the pollutant. Finally, analyzing the degradation rates at various initial PhE concentrations (2-400 mg L) with a heterogeneous Langmuir type mechanism underlined the predominance of interfacial radical reactions during the oxidation of PhE, particularly at high initial pollutant concentrations.

A semi‐empirical approach for determining the number density and void fraction of acoustic cavitation bubbles in sono‐reactors

“…In addition, in the present paper, the thermal conductivity of the gas (inside the bubble) is evaluated through its dependency on the temperature and the density of gas and vapor mixture (see Equation (S8), Table S1). On the other hand, the accommodation coefficient of Equation (S5) is calculated as follows: 51 (1) − 0.05k (2) + 0.025k (3)…”

“…A range of industrial and scientific applications benefit from the advantageous physical and chemical effects produced by these critical conditions. [1][2][3][4][5][6][7][8][9][10] However, the control and optimization of cavitation systems are challenging and have been the subject of various research because of the chaotic nature of acoustic cavitation bubbles. In general, the analysis of size distribution, bubbles coalescence, bubble deformation, void fraction (total volume of bubbles), secondary Bjerknes force and other phenomena were the subjects of numerous theoretical and experimental works.…”

“…Within the sono‐irradiated field, the collapse of micron‐sized bubbles produces enormous pressures (several hundred atmospheres) and temperatures (thousands of degree Kelvin). A range of industrial and scientific applications benefit from the advantageous physical and chemical effects produced by these critical conditions 1–10 . However, the control and optimization of cavitation systems are challenging and have been the subject of various research because of the chaotic nature of acoustic cavitation bubbles.…”

Efficient purification of wastewater by applying mechanical force and BaCO3/TiO2 and BaTiO3/TiO2 piezocatalysts

“…In this situation, degradation energy came from acoustic cavitation which was the formation, growth, and implosive collapse of bubbles in a solvent. 3,35,36 When bubbles were collapsed huge energy was released and this released energy could produce some hydroxyl radicals. 35,36 These radicals were responsible for the degradation of 31.2% of AR151 in absence of piezocatalysts.…”

“…3,35,36 When bubbles were collapsed huge energy was released and this released energy could produce some hydroxyl radicals. 35,36 These radicals were responsible for the degradation of 31.2% of AR151 in absence of piezocatalysts. When nanopiezocatalysts were used, 78.4% of AR151 was degraded in the same ultrasonic time and power (sample 1).…”