Enhanced sonochemical degradation of bisphenol-A by bicarbonate ions

Abstract

Sonochemical elimination of organic pollutants can take place through two degradation pathways. Molecules with relatively large Henry's law constants will be incinerated inside the cavitation bubble, while nonvolatile molecules with low Henry's law constants will be oxidised by the OH(*) ejected from the bubble of cavitation. Taking bisphenol-A as a model pollutant, this study points out an alternate degradation route, mediated by bicarbonate ions, which is significant for the elimination of micro-pollutants at concentrations present in natural waters. In this process, OH(*) radicals react with bicarbonate ions to produce the carbonate radical, which, unlike the OH(*) radical, can migrate towards the bulk of the solution and therefore induce the degradation of the micro-pollutants present in the bulk solution. As a consequence, initial degradation rate is increased by a factor 3.2 at low concentration of bisphenol-A (0.022 micromol l(-1)) in presence of bicarbonate in water.

Sonochemical Formation of Hydrogen Peroxide

“…It is well known that removal of organic pollutants depends on amounts of reactive species, with this, in turn, being dependent on the presence of additional substances in the reaction solution that can act as radical scavengers. Inorganic ions and organic substances are, in fact, well-known OH scavengers [30,31]. In a previous study [23], the ultrasonic degradation of bisphenol-A was also shown to be impacted upon negatively by humic acid.…”

Low concentrations of bisphenol a suppress thyroid hormone receptor transcription through a nongenomic mechanism

“…Almost confluent cells were placed for 2 days in medium containing serum and then in serum-free medium for 2 h. Cells were then treated with 10 − 10 M T3 or 10 − 7 M T4 combined with the indicated amounts of BPA for the times indicated. Both the plastic experimental items and the water utilized to prepare the reagents were pretreated by the enhanced sonochemical degradation to reduce any potential background BPA (Pétrier et al, 2010).…”

Photocatalytic degradation of carbamazepine using hierarchical BiOCl microspheres: Some key operating parameters, degradation intermediates and reaction pathway

“…1) . , which, unlike the •OH, could migrate to the bulk solution and induced the degradation of the CBZ molecules [34,35]. However, excess HCO 3 -(150 and 200 mg· L -1 ) would also compete with CBZ molecules for •OH to form much less reactive inorganic radical species (Eq 6) [28], leading to the reduced degradation rate.…”