Sonochemical reactor characterization in the presence of cylindrical and conical reflectors.

Ultrasonic systems must be able to produce an acoustic field with the highest possible energy concentration in sonochemical reactors to accomplish maximum efficacy in the sonolytic degradation of water contaminants. In the present study, the impact of cylindrical and conical stainless-steel reflectors placed on the liquid surface on the sonochemical oxidation activity of ultrasonication reactors was investigated. The amount of effective acoustic power transferred to the ultrasonicated medium without and with reflectors was measured by calorimetric characterization of the sono-reactors at diverse ultrasonication frequencies in the interval of 300-800 kHz and different electrical powers in the range of 40-120 W. Iodide dosimetry without and with reflectors at diverse ultrasonication conditions (300-800 kHz and 40-120 W) and various aqueous solution volumes in the range of 300-500 mL was used to assess the sonochemical oxidation activity, i.e., the generation of oxidative species (mainly hydroxyl radicals). Sonochemiluminescence (SCL) imaging was used to study the active acoustic cavitation bubbles distribution in the sono-reactors without and with reflectors. Significant impacts of the position and shape of the reflectors on the active acoustic cavitation bubble distribution and the sonochemical oxidation activity were observed due to remarkable modifications of the ultrasonic field by directing and focusing of the ultrasonic waves. A significant augmentation in the triiodide formation rate was obtained in the presence of the conical reflector, especially at 630 kHz and 120 W (60.5% improvement), while iodide oxidation was quenched in the presence of the cylindrical reflector at all ultrasonication frequencies and powers. The SCL images show a noteworthy modification in the ultrasonic field and the acoustic cavitation bubble population when reflectors were used. The sonochemical oxidation activity was improved by the conical reflector when placed in the Fresnel zone (near field region).

Sonochemical formation of peroxynitrite in water: Impact of ultrasonic frequency and power.

There is a lack of literature on peroxynitrite formation due to sonolysis of aerated water. In this work, the impact of sonication parameters, frequency and power, on ultrasonic peroxynitrite production in aerated alkaline water was investigated. Peroxynitrite formation was clearly established with undeniable evidence at all the tested frequencies in the range of 516-1140 kHz with a typical G-value (energy-specific yield) of 0.777 × 10-10, 0.627 × 10-10, 0.425 × 10-10 and 0.194 × 10-10 mol/J at 516, 558, 860 and 1140 kHz, respectively. The ultrasonication frequency has a direct impact on the sonochemical peroxynitrite production. Increasing the ultrasonication frequency in the interval 321-1140 kHz reduces peroxynitrite formation. The most practical sonochemistry dosimetries, including hydrogen peroxide production, triiodide dosimetry, Fricke dosimetry, and 4-nitrocatechol formation, were compared with the sonochemical efficiency of the reactors used to produce peroxynitrite. The G-value, energy specific yield, for the tested dosimetries was higher than that for peroxynitrite formation, regardless of frequency. For all chemical dosimetries investigated, the same trend of frequency dependence was found as for peroxynitrite generation. The influence of ultrasonication power on peroxynitrite formation by sonication at diverse frequencies in the interval 585-1140 kHz was studied. No peroxynitrite was formed at lower acoustic power levels, regardless of frequency. As the frequency increases, more power is required for peroxynitrite formation. The production of peroxynitrite increased as the acoustic power increased, despite the frequency of ultrasonic waves. Ultrasonic power is a key factor in the production of peroxynitrite by sonolysis. Since peroxynitrite is uniformly distributed in the bulk solution, peroxynitrite-sensitive solutes can be transformed both in the bulk of the solution and in the surfacial region (shell) of the cavitation bubble. The formation of peroxynitrite should be taken into account in sonochemistry, especially at higher pH values. Ultrasonic peroxynitrite formation in alkaline solution (pH 12) can be considered as a kind of chemical dosimetry in sonochemistry.

Sonochemical Degradation of Benzothiophene (BT) in Deionized Water, Natural Water and Sea Water.

This paper deals with the sonochemical water treatment of polycyclic aromatic sulfur hydrocarbons (PASHs), one of the most common impurities found in waste water coming from petroleum industry. The best fit of the experimental data appears to be the kinetic parameters determined using the Michaelis-Mentonmodel in the concentrations range of the study. For the initial increase in the degradation rates, it is simply considered that the more the bulk concentration increases, the more the concentration in the interfacial region increases. This will be explained by Michaelis-Menton kinetics. The influence of organic compounds in the water matrix as a mixture with Benzothiophene (BT) was also evaluated. The results indicated that BT degradation is unaffected by the presence of bisphenol A (BPA). Finally, the results indicated that ultrasonic action is involved in oxidation rather than pyrolitic processing in the BT sonochemical degradation.

Persulfate-enhanced sonochemical degradation of naphthol blue black in water: Evidence of sulfate radical formation.

This work explores the effect of persulfate (PS) on the sonochemical degradation of organic pollutants taking naphthol blue black (NBB), an anionic diazo dye, as a substrate model. The sonolytic experiments were conducted in the absence and presence of PS under various experimental conditions including acoustic power (10-80W), frequency (20 and 585kHz) and saturating gas (argon, air and nitrogen). Experimental results showed that PS decomposition into sulfate radical (SO4-) takes place by sonolysis and increasing PS concentration up to 1g/L would result in an increase in the NBB degradation rate. It was found that the PS-enhanced effect was strongly operating parameters dependent. The positive effect of PS decreased with increasing power and the best enhancing effect was obtained for the lowest acoustic power. Correspondingly, the PS-enhanced effect was more remarkable at low frequency (20kHz) than that observed at high frequency ultrasound (585kHz). Nitrogen saturating gas gave the best enhanced effect of PS than argon and air atmospheres. Theoretical (computer simulation of bubble collapse) and experimental measurements of the yields of free radical generation under the different experimental conditions have been made for interpreting the obtained effects of PS on the sonochemical degradation of the dye pollutant. The experimental findings were attributed to the fact that radical-radical recombination reactions occur at faster rate than the radical-organic reaction when the concentration of free radicals is too high (at higher sonochemical conditions).

Effect of potassium monopersulfate (oxone) and operating parameters on sonochemical degradation of cationic dye in an aqueous solution.

In this study, removal of Cresol Red (CR), a cationic triphenylmethane dye, by 300kHz ultrasound was investigated. The effect of additive such as potassium monopersulfate (oxone) was studied. Additionally, sonolytic degradation of CR was investigated at varying power and initial pH. RC can be readily eliminated by the ultrasound process. The obtained results showed that. Sonochemical degradation of CR was strongly affected by ultrasonic power and pH. The degradation rate of the dye increased substantially with increasing ultrasonic power in the range of 20-80W. This improvement could be explained by the increase in the number of active cavitation bubbles. The significant degradation was achieved in acidic conditions (pH=2) where the color removal was 99% higher than those observed in higher pH aqueous solutions. The ultrasonic degradation of dye was enhanced by potassium monopersulfate (oxone) addition. It was found that the degradation of the dye was accelerated with increased concentrations of oxone for a reaction time of 75min.

Enhancement and inhibition effects of water matrices during the sonochemical degradation of the antibiotic dicloxacillin.

The sonochemical degradation of dicloxacillin (DXC) was studied in both synthetic and natural waters. Degradation routes and the effect of experimental conditions such as pH, initial DXC concentration and ultrasonic power were evaluated. Experiments were carried out with a fixed frequency (600kHz). The best performances were achieved using acidic media (pH=3) and high power (60W). The degradation process showed pseudo-first order kinetics as described by the Okitsu model. To evaluate water matrix effects, substrate degradation, in the presence of Fe(2+) and organic compounds such as glucose and 2-propanol, was studied. A significant improvement was achieved with Fe(2+) (1.0mM). Inhibition of the degradation process was observed at a relatively high concentration of 2-propanol (4.9mM), while glucose did not show any effect. Natural water showed an interesting effect: for a low concentration of DXC (6.4µM), an improvement in the degradation process was observed, while at a higher concentration of DXC (0.43mM), degradation was inhibited. Additionally, the extent of degradation of the process was evaluated through the analysis of chemical oxygen demand (COD), antimicrobial activity, total organic carbon (TOC) and biochemical oxygen demand (BOD5). A 30% removal of COD was achieved after the treatment and no change in the TOC was observed. Antimicrobial activity was eliminated after 360min of ultrasonic treatment. After 480min of treatment, a biodegradable solution was obtained.

Ultrasound enhancement of near-neutral photo-Fenton for effective E. coli inactivation in wastewater.

In this study, we attempt for the first time to couple sonication and photo-Fenton for bacterial inactivation of secondary treated effluent. Synthetic wastewater was subjected to sequential high-frequency/low power sonication, followed by mild photo-Fenton treatment, under a solar simulator. It was followed by the assessment of the contribution of each component of the process (Fenton, US, hv) towards the removal rate and the long-term survival; sunlight greatly improved the treatment efficiency, with the coupled process being the only one to yield total inactivation within the 4-h period of treatment. The short-term beneficial disinfecting action of US and its detrimental effect on bacterial survival in long term, as well as the impact of light addition were also revealed. Finally, an investigation on the operational parameters of the process was performed, to investigate possible improvement and/or limitations of the coupled treatment; 3 levels of each parameter involved (hydraulic, environmental, US and Fenton) were tested. Only H2O2 increased improved the process significantly, but the action mode of the joint process indicated potential cost-effective solutions towards the implementation of this method.

Ultrasonic degradation of acetaminophen in water: effect of sonochemical parameters and water matrix.

This paper deals about the sonochemical water treatment of acetaminophen (ACP, N-acetyl-p-aminophenol or paracetamol), one of the most popular pharmaceutical compounds found in natural and drinking waters. Effect of ultrasonic power (20-60 W), initial ACP concentration (33-1323 µmol L(-1)) and pH (3-12) were evaluated. High ultrasonic powers and, low and natural acidic pH values favored the efficiency of the treatment. Effect of initial substrate concentration showed that the Langmuir-type kinetic model fit well the ACP sonochemical degradation. The influence of organic compounds in the water matrix, at concentrations 10-fold higher than ACP, was also evaluated. The results indicated that only organic compounds having a higher value of the Henry's law constant than the substrate decrease the efficiency of the treatment. On the other hand, ACP degradation in mineral natural water showed to be strongly dependent of the initial substrate concentration. A positive matrix effect was observed at low ACP concentrations (1.65 µmol L(-1)), which was attributed to the presence of bicarbonate ion in solution. However, at relative high ACP concentrations a detrimental effect of matrix components was noticed. Finally, the results indicated that ultrasonic action is able to transform ACP in aliphatic organic compounds that could be subsequently eliminated in a biological system.

Starch nanoparticles formation via high power ultrasonication.

Nano-sized starch particles (NSP) were prepared from starch granules using a purely physical method of high-intensity ultrasonication. Particle size distribution, Field Effect Scanning Electron Microscopy (FE-SEM), Raman spectroscopy, and Wide-Angle X-ray Diffraction (WAXD) were used to characterize the morphology and crystal structure of the ensuing nanoparticles. The results revealed that ultrasound treatment of the starch suspension in water and at low temperature for 75 min results in the formation of starch nanoparticles between 30 and 100 nm in size. An attempt to explain the generation of starch nanoparticles was made on the basis of WAXD, Raman analysis and FE-SEM observation. Compared to acid hydrolysis, which is the most commonly adopted process, the present approach has the advantage of being quite rapid, presenting a higher yield and not requiring any chemical treatment.

Low-frequency ultrasound induces oxygen vacancies formation and visible light absorption in TiO2 P-25 nanoparticles.

Low-frequency ultrasound (LFUS) irradiation induces morphological, optical and surface changes in the commercial nano-TiO(2)-based photocatalyst, Evonik-Degussa P-25. Low-temperature electron spin resonance (ESR) measurements performed on this material provided the first experimental evidence for the formation of oxygen vacancies (V(o)), which were also found responsible for the visible-light absorption. The V(o) surface defects might result from high-speed inter-particle collisions and shock waves generated by LFUS sonication impacting the TiO(2) particles. This is in contrast to a number of well-established technologies, where the formation of oxygen vacancies on the TiO(2) surface often requires harsh technological conditions and complicated procedures, such as annealing at high temperatures, radio-frequency-induced plasma or ion sputtering. Thus, this study reports for the first time the preparation of visible-light responsive TiO(2)-based photocatalysts by using a simple LFUS-based approach to induce oxygen vacancies at the nano-TiO(2) surface. These findings might open new avenues for synthesis of novel nano-TiO(2)-based photocatalysts capable of destroying water or airborne pollutants and microorganisms under visible light illumination.

Effects of sonochemical parameters and inorganic ions during the sonochemical degradation of crystal violet in water.

This work deals with the ultrasonic degradation (800 kHz) of crystal violet (CV) under different experimental conditions. The effects of saturating gas (argon, carbon dioxide and air), CV concentration (2.45-1225 µmol L(-1)), pH (3-9) and power (20-80 W) were evaluated. The best performances were obtained at 80 W with argon as a saturating gas. The pH had no significant effect. The influence of several water matrices containing anions (chloride, sulphate and bicarbonate) and cations (Fe(2+)) on the sonolytic degradation of CV was also investigated. Significant differences were not observed with the presence of chloride and sulphate. However, at relatively low pollutant concentration (2.45 µmol L(-1)) bicarbonate showed a particular effect: a high bicarbonate concentration (350 mmol L(-1)) produced a detrimental effect, while a low bicarbonate concentration (3 mmol L(-1)) increased the efficiency of the process. The presence of Fe(2+) (1 mmol L(-1)) also increased the CV (49 µmol L(-1)) degradation by 32% after 180 min. Analyses of intermediates by GC-MS led to the identification of several sonochemical by-products: N,N-dimethylaminobenzene, 4-(N,N-dimethylamino)-4'-(N',N'-dimethylamino)benzophenone, and N,N,N',N'-tetramethyl-4,4'-diaminodiphenylmethane. The presence of these aromatic structures showed that the main ultrasonic CV degradation pathway is linked to the reaction with *OH radicals. At the end of the treatment, these early products were converted into biodegradable organic by-products which could be easily treated in a subsequent biological treatment.

Secondary sonochemical effect on Mo-catalyzed bromination of aromatic compounds.

The Molybdate-catalyzed bromination of various aromatic compounds in the presence of KBr/H(2)O(2) in an aqueous/chloroform biphasic system occurred under ultrasonic irradiation, whereas the reaction did not take place under conventional mechanical stirring (1400 rpm). The sonochemical activation was found to be of secondary effect, attributed to lowering pH by sonolysis of CHCl(3)-H(2)O solvents mixture.

Modeling of ultrasonic degradation of non-volatile organic compounds by Langmuir-type kinetics.

Sonochemical degradation of phenol (Ph), 4-isopropylphenol (4-IPP) and Rhodamine B (RhB) in aqueous solutions was investigated for a large range of initial concentrations in order to analyze the reaction kinetics. The initial rates of substrate degradation and H(2)O(2) formation as a function of initial concentrations were determined. The obtained results show that the degradation rate increases with increasing initial substrate concentration up to a plateau and that the sonolytic destruction occurs mainly through reactions with hydroxyl radicals in the interfacial region of cavitation bubbles. The rate of H(2)O(2) formation decreases with increasing substrate concentration and reaches a minimum, followed by almost constant production rate for higher substrate concentrations. Sonolytic degradation data were analyzed by the models of Okitsu et al. [K. Okitsu, K. Iwasaki, Y. Yobiko, H. Bandow, R. Nishimura, Y. Maeda, Sonochemical degradation of azo dyes in aqueous solution: a new heterogeneous kinetics model taking into account the local concentration OH radicals and azo dyes, Ultrason. Sonochem. 12 (2005) 255-262.] and Seprone et al. [N. Serpone, R. Terzian, H. Hidaka, E. Pelizzetti, Ultrasonic induced dehalogenation and oxidation of 2-, 3-, and 4-chlorophenol in air-equilibrated aqueous media. Similarities with irradiated semiconductor particulates, J. Phys. Chem. 98 (1994) 2634-2640.] developed on the basis of a Langmuir-type mechanism. The five linearized forms of the Okitsu et al.'s equation as well as the non-linear curve fitting analysis method were discussed. Results show that it is not appropriate to use the coefficient of determination of the linear regression method for comparing the best-fitting. Among the five linear expressions of the Okitsu et al.'s kinetic model, form-2 expression very well represent the degradation data for Ph and 4-IPP. Non-linear curve fitting analysis method was found to be the more appropriate method to determine the model parameters. An excellent representation of the experimental results of sonolytic destruction of RhB was obtained using the Serpone et al.'s model. The Serpone et al.'s model gives a worse fit for the sonolytic degradation data of Ph and 4-IPP. These results indicate that Ph and 4-IPP undergo degradation predominantly at the bubble/solution interface, whereas RhB undergoes degradation at both bubble/solution interface and in the bulk solution.

An innovative ultrasound, Fe(2+) and TiO(2) photoassisted process for bisphenol A mineralization.

This paper explores the degradation of a model pollutant, bisphenol A, by an advanced oxidation process that combines sonolysis, Fe(2+), and TiO(2) in a photoassisted process. Experiments were done under saturated oxygen conditions. The effect of different Fe(2+) (0.56 and 5.6 mg/L) and TiO(2) (10 and 50 mg/L) concentrations was investigated on both the elimination and mineralization of the pollutant. A pronounced synergistic effect that led to the complete and rapid elimination of dissolved organic carbon (DOC) was observed even at low catalyst loadings. In this system, almost a complete removal of DOC (93%) was observed after 4 h using 10 and 5.6 mg/L of TiO(2) and Fe(2+), respectively, whereas at the same time, only 5, 6, and 22% of DOC was removed by an individual process alone (TiO(2) photocatalysis, ultrasound, and photo-Fenton, respectively). In this system, ultrasound has the principal role of eliminating the initial substrate and providing hydrogen peroxide for the photocatalytic systems, while photo-Fenton and TiO(2) photocatalysis are mainly responsible for the transformation of the intermediates in CO(2) and H(2)O. The role of H(2)O(2) generated from the sonochemical process is also discussed.

Influence of bicarbonate and carbonate ions on sonochemical degradation of Rhodamine B in aqueous phase.

The influence of bicarbonate and carbonate ions on sonolytic degradation of cationic dye, Rhodamine B (RhB), in water was investigated. As a consequence of ultrasonic cavitation that generates .OH radicals, carbonate radicals were secondary products of water sonochemistry when it contains dissolved bicarbonate or carbonate ions. The results clearly demonstrated the significant intensification of sonolytic destruction of RhB in the presence of bicarbonate and carbonate, especially at lower dye concentrations. Degradation intensification occurs because carbonate radicals sonochemically formed undergo radical-radical recombination at a lesser extent than hydroxyl radicals. The generated carbonate radicals are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as RhB. Therefore, at low dye concentrations, carbonate radical presents a more selective reactivity towards RhB molecules than hydroxyl radical. In the presence of bicarbonate, degradation rate reached a maximum at 3 g L(-1) bicarbonate, but subsequent addition retards the destruction process. In RhB solutions containing carbonate, the oxidation rate gradually increased with increasing carbonate concentration up to 10 g L(-1) and slightly decreased afterward. Carbonate radicals sonochemically generated are suitable for total removal of COD of sonicated RhB solutions.

Study on ultrasonically assisted emulsification and recovery of copper(II) from wastewater using an emulsion liquid membrane process.

The aim of this work was to study the emulsification assisted by ultrasonic probe (22.5kHz) and investigate the removal of copper(II) ions from aqueous solution using water-in-oil-in-water (W/O/W) emulsion liquid membrane process (ELM). The membrane was prepared by dissolving the extractant bis(2-ethylhexyl)phosphoric acid (D2EHPA) and the hydrophobic surfactant sorbitan monooleate (Span 80) in hexane (diluent). The internal phase consisted of an aqueous solution of sulfuric acid. Effects of operating parameters such as emulsification time, ultrasonic power, probe position, stirring speed, carrier (D2EHPA) and surfactant (Span 80) concentrations volume ratios of organic phase to internal striping phase and of external aqueous phase to membrane (W/O) phase, internal phase concentration and choice of diluent on the membrane stability were studied. With ultrasound, the W/O emulsion lifetime were much higher than those reported previously by mechanical agitation. The effect of carrier and Cu(II) initial concentration on the extraction kinetics was also investigated. Nearly all of the Cu(II) ions present in the continuous phase was extracted within a few minutes. Additionally, the influence of H(2)SO(4) concentration on the stripping efficiency was examined.

Enhanced sonochemical degradation of bisphenol-A by bicarbonate ions.

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.

Effectiveness of ultrasound for the destruction of Mycobacterium sp. strain (6PY1).

Ultrasound is widely used to disinfect drinking water and wastewater due to its strong physical and chemical effects on microorganisms. The aim of this study was to investigate the effect of ultrasound on the destruction of Mycobacterium strain 6PY1. Ultrasound waves (20 kHz or 612 kHz) were used to treat aqueous suspensions of Mycobacterium at different volumes, initial bacterial concentrations, and power densities. At the same power density and the same exposure time, sonication at high frequency resulted in a lower destruction of Mycobacterium sp. 6PY1 (35.5%) than sonication at low frequency (93%). The percentage of removal was not significantly affected by the volume of the irradiated suspension (150-300 ml) or the initial cell concentration (2.15 x 10(-3)-1.4 x 10(-2)mg protein L(-1)). At low frequency, the removal percentage of Mycobacterium sp. 6PY1 increased with increasing the power density, with a constant level reached after a certain power density. At high frequency, the removal percentage of Mycobacterium sp. 6PY1 increased with increasing the power density. The mechanism of cell killing was investigated by examining the effects of OH() radical scavengers such as sodium carbonate. At high frequency the presence of sodium carbonate suppressed the removal process. However, at low frequency the removal process was not affected, thus indicating that OH() radicals have a negligible role in this case. The latter result was supported by ten time's H(2)O(2) production at high frequency greater than that at low frequency.

Experimental design approach to the optimization of ultrasonic degradation of alachlor and enhancement of treated water biodegradability.

This work presents the application of experimental design for the ultrasonic degradation of alachlor which is pesticide classified as priority substance by the European Commission within the scope of the Water Framework Directive. The effect of electrical power (20-80W), pH (3-10) and substrate concentration (10-50mgL(-1)) was evaluated. For a confidential level of 90%, pH showed a low effect on the initial degradation rate of alachlor; whereas electrical power, pollutant concentration and the interaction of these two parameters were significant. A reduced model taking into account the significant variables and interactions between variables has shown a good correlation with the experimental results. Additional experiments conducted in natural and deionised water indicated that the alachlor degradation by ultrasound is practically unaffected by the presence of potential *OH radical scavengers: bicarbonate, sulphate, chloride and oxalic acid. In both cases, alachlor was readily eliminated ( approximately 75min). However, after 4h of treatment only 20% of the initial TOC was removed, showing that alachlor by-products are recalcitrant to the ultrasonic action. Biodegradability test (BOD5/COD) carried out during the course of the treatment indicated that the ultrasonic system noticeably increases the biodegradability of the initial solution.

Ultrasonic cavitation applied to the treatment of bisphenol A. Effect of sonochemical parameters and analysis of BPA by-products.

Bisphenol A (BPA), a chemical compound largely used in the plastics industry, can end up in aquatic systems, which it disturbs by its endocrine disrupting effect (EDE). This study investigated the BPA degradation upon ultrasonic action under different experimental conditions. The effect of saturating gas (oxygen, argon and air), BPA concentration (0.15-460 micromol L(-1)), ultrasonic frequency (300-800 kHz) and power (20-80 W) were evaluated. For a 118 micromol L(-1)-BPA solution, with the best performance obtained at 300 kHz, 80 W, with oxygen as saturating gas. In these conditions, BPA can be readily eliminated by the ultrasound process (approximately 90 min). However, even after long ultrasound irradiation times (9 h), more than 50% of chemical oxygen demand (COD) and 80% of total organic carbon (TOC) remained in the solution. Analyses of intermediates using HPLC-MS investigation identified several products: monohydroxylated bisphenol A, 4-isopropenylphenol, quinone of monohydroxylated bisphenol A, dihydroxylated bisphenol A, quinone of dihydroxylated bisphenol A, monohydroxylated-4-isopropenylphenol and 4-hydroxyacetophenone. The presence of these hydroxylated aromatic structures showed that the main ultrasonic BPA degradation pathway is related to the reaction of BPA with the *OH radical. After 2h, these early products were converted into biodegradable aliphatic acids.