Sonochemical Processes Research Articles

Sonochemical degradation of methyl orange in the presence of Bi2WO6: Effect of operating parameters and the generated reactive oxygen species

The Bi2WO6 was prepared by the hydrothermal method and its sonocatalytic activity was studied in the degradation of methyl orange (MO) solutions. The effects of catalytic activity of Bi2WO6 on dye were inspected by the change in absorbance of dye with UV–vis spectrometer. The influences of operational parameters such as the addition amount of Bi2WO6, pH, the initial concentration of dyes, ultrasonic power and irradiation time on the degradation ratio were investigated. In addition, the obtained results indicated that the kinetics of sonochemical reactions of MO were consistent with the pseudo first-order kinetics and Bi2WO6 had excellent reusability and stability during the sonochemical degradation processes. The generation and kinds of reactive oxygen species (ROS) and their influence on the sonochemical degradation of MO were determined by the methods of oxidation–extraction spectrophotometry and ROS scavengers. The results indicate that the degradation of MO in the presence of Bi2WO6 under ultrasonic irradiation is related to the generation of ROS, in which both singlet molecular oxygen (1O2) and hydroxyl radical (OH) play important roles in the sonochemical degradation of MO. These experimental results provide a sound foundation for the further development of Bi2WO6 as a sonocatalyst in wastewater treatment.

Advanced oxidation processes: a review regarding the fundamentals and applications in wastewater treatment and industrial wastewater

Contamination of water by toxic and/or recalcitrant species has great environmental impacts. In this context, Advanced Oxidation Processes (AOPs) - technologies that principally use the hydroxyl radical (HO●) for oxidation - have emerged as promising alternatives in treating urban and industrial wastewaters. This study reviewed the literature on POAs and presented data regarding the efficiency of these processes in pollutant degradation, comparing the theoretical reasoning and its industrial applications. The fundamentals and major applications of AOPs (chemical, photochemical, electrochemical, sonochemical and ozone-based processes), as well as their advantages and disadvantages, are described in this review. AOPs have been considered an effective alternative from a technical, economic and environmental viewpoint for the degradation of pollutants in effluents and industrial wastewater, despite having limitations such as high cost of available energy sources, development of new low-cost catalytic materials and construction of full-scale reactors. It is greatly important to the industrial application of AOPs to optimize the effectiveness of these factors.

Impact of ultrasound application on oxidative desulphurization of diesel fuel and on treatment of resulting wastewater

The ultrasound-assisted oxidative desulphurization (UAOD) process of diesel fuel has gained growing attention due to the strict regulation of sulphur content in the fuel. The goal of the present study was to investigate the impact of ultrasound (US) application for oxidative desulphurization (ODS) of hydrocarbon fuels and for the subsequent treatment of produced wastewater, since sonochemical processes are a new and interesting area of research with wide application in the field of environmental engineering. For that purpose, the model diesel fuel with initial sulphur concentration of 1220–3976 mg l−1 was used for ODS and UAOD tests, and hydrogen peroxide/acetic acid was applied as the oxidant/catalyst system, respectively. The comparison of the process performance revealed that US significantly reduced the oxidation reaction time. The conversions of dibenzothiophene during 30 min of ODS and UAOD tests were 36% and 87%, respectively. Moreover, subsequent extraction with acetonitrile resulted in the final sulphur removal of 96.5%. The obtained results clearly indicated that UAOD process is beneficial for effective sulphur removal from the model diesel fuel. Furthermore, subsequent experiments included the application of the sono-Fenton process for resulting wastewater treatment. Monitoring of dibenzothiophene sulphone concentration and total organic carbon during the sono-Fenton treatment of wastewater revealed the decrease of 70–75% and 53–66%, respectively. The hypothesis on the possibility of degradation of dibenzothiophene sulphone by •OH radicals was confirmed by observed generation of benzoic acid and aliphatic carboxylic acids during experiments. Accordingly, the wastewater was purified to a satisfactory degree, enabling the reuse of treated water.

Sonochemical techniques to degrade pharmaceutical organic pollutants

Pharmaceuticals are one of the chemical groups largely used in health care, diagnosis aids, cure, treatment, and prevention of disease. Increasing production and use of pharmaceutical products has led to the entry of these products into the environment and eventual pollution. Several processes have been studied including the use of ultrasound for the removal of these pollutants from the aquatic environment. This review summarizes recent research advances dealing with the development of sonochemical technologies for the degradation of pharmaceutical organic pollutants. The review also includes the mechanism of sonochemical processes, the characteristics of irradiation sources, and the types of reactors used. Moreover, the important factors affecting the sonochemical oxidation efficiency are discussed, including the electrical power, frequency, and temperature. Finally, this paper discusses the recent applications of sonochemical processes on the degradation of pharmaceutical organic pollutants and suggests new research directions for the development of this promising technology.

ChemInform Abstract: Organic Reactions in Water or Biphasic Aqueous Systems under Sonochemical Conditions. A Review on Catalytic Effects

AbstractReview: 35 refs.

파 에너지 (자외선, 초음파)/과황산나트륨을 이용한 이부프로펜 분해특성 연구

Abstract In this study, ibuprofen(IBP) degradation by the photochemical (UV/S 2 O 82- ) and sonochemical (US/S 2 O 82- ) processes was examined under various parameters, such as UV (10~40±5 W/L) and US (50~90±5 W/L) power density, optimum dosage of persulfate ion (S 2 O 82- ), temperature (20~60℃) and anions effect (Cl - , HCO 3- , CO 32- ). The pseudo‐first‐order degradation rate constants were in the order of 10 -1 to 10 -5 min -1 depending on each processes. The synergistic effect of IBP degradation in UV/S 2 O 82- and US/S 2 O 82- processes could investigated, due to the generation of SO 4- radical. This result can confirm from the produced H 2 O 2 and SO 42- concentration in each processes. IBP degradation rate affected by the S 2 O 82- dosage, temperature, power and anion existence parameters. In particular, IBP degradation rate increased with the increase of the temperature (60℃) and applied power density (UV:40±5 W/L, US:90±5 W/L). On the other hand, anions effect on the IBP degradation was negative, due to the anion play as a the scavenger of radical.

Sonochemical effectiveness factor (eUS) in the reactors for wastewater treatment by sono-Fenton oxidation: Novel considerations

A comprehensive algorithm was recently proposed for calculation of the sonochemical effectiveness factor and wastewater treatment modeling. The presented approach implies that ultrasound is an auxiliary source of free radicals in Fenton type reactions; introduction of ultrasound represents an enhancement of pollutant degradation rates. The sonochemical effectiveness factor was introduced in kinetic models as the eUS factor (Grčić et al., 2012 [1]). As a substantial follow-up, this study presents novel considerations. The eUS factor was modeled as a function of employed frequency, actual cavitation-related power intensity of ultrasound and a portion of the cavitationally active zone, i.e. dimensionless active volume. The effect of temperature was disregarded in the present model considerations. Cavitationally active zone in reactors was determined based on the erosion of aluminum foil, resulting in cone-shaped space arising from transducer.In the present study, sonochemical treatment of industrial wastewater containing HCOONa as organic pollutant was performed using different equipment: ultrasonic baths (UB1, UB2 and UB3), cylindrical reactor with homogenizer (HCR) and three-frequency hexagonal cell, i.e. ultrasonic pilot reactor prototype (PP). Explored frequency range was from 20 to 120kHz. Homogeneous and heterogeneous Fenton-type sonochemical processes, US/Fe(II)(FeSO4,aq.)/H2O2 and US/Fe(II)(steel-plate)/H2O2, respectively, applied to industrial wastewater were investigated in terms of mineralization kinetics. Newly modeled eUS factor was introduced in corresponding kinetic models and the overall model was validated. Kinetic parameters of Fenton process were treated as independent of ultrasound, since eUS factor consists of cavitation-related phenomena responsible for the mineralization rate enhancement. In average, a 21% increase of mineralization efficiency was achieved using a single frequency, while more than 70% increase can be achieved by combining 20, 68 and 120kHz in PP.

Effectiveness of photochemical and sonochemical processes in degradation of Basic Violet 16 (BV16) dye from aqueous solutions.

In this study, degradation of Basic Violet 16 (BV16) by ultraviolet radiation (UV), ultrasonic irradiation (US), UV/H2O2 and US/H2O2 processes was investigated in a laboratory-scale batch photoreactor equipped with a 55W immersed-type low-pressure mercury vapor lamp and a sonoreactor with high frequency (130kHz) plate type transducer at 100W of acoustic power. The effects of initial dye concentration, concentration of H2O2 and solution pH and presence of Na2SO4 was studied on the sonochemical and photochemical destruction of BV16 in aqueous phase. The results indicated that in the UV/H2O2 and US/H2O2 systems, a sufficient amount of H2O2 was necessary, but a very high H2O2 concentration would inhibit the reaction rate. The optimum H2O2 concentration was achieved in the range of 17 mmol/L at dye concentration of 30 mg/L. A degradation of 99% was obtained with UV/H2O2 within 8 minutes while decolorization efficiency by using UV (23%), US (<6%) and US/H2O2(<15%) processes were negligible for this kind of dye. Pseudo-first order kinetics with respect to dyestuffs concentrations was found to fit all the experimental data.

The effect of molecular weight and catalyst concentration on catalytic activity in mechanochemically activated transesterification using silver(I)‐N‐heterocyclic carbene latent catalysts

AbstractWe have investigated the effect of the concentration and molecular weight on the activity of polymeric silver(I)‐NHC (NHC = N‐heterocyclic carbene) catalyst complexes in ultrasound‐induced mechanochemical catalyst activation. A strong dependence of the turnover number (TON) on initial catalyst concentration was observed in the transesterification of vinyl acetate with benzyl alcohol. The main findings of this study are that the concentration and molecular weight effects on TON are caused by competition between mechanochemical catalyst activation and deactivation, most likely by reactive species produced during the sonication process. Performing the transesterification reaction under radical‐suppressing conditions resulted in a significant increase of TON. This result clearly demonstrates the increased catalyst lifetime when reducing the amount of sonochemical impurities, and it highlights the importance of controlling and suppressing secondary, sonochemical processes when using ultrasound‐induced mechanochemical generation of reactive species such as catalysts. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Correlation between iodide dosimetry and terephthalic acid dosimetry to evaluate the reactive radical production due to the acoustic cavitation activity

Acoustic cavitation plays an important role in sonochemical processes and the rate of sonochemical reaction is influenced by sonication parameters. There are several methods to evaluate cavitation activity such as chemical dosimetry. In this study, to comparison between iodide dosimetry and terephthalic acid dosimetry, efficacy of sonication parameters in reactive radical production has been considered by iodide and terephthalic acid dosimetries. For this purpose, efficacy of different exposure parameters on cavitations production by 1MHz ultrasound has been studied. The absorbance of KI dosimeter was measured by spectrophotometer and the fluorescence of terephthalic acid dosimeter was measured using spectrofluorometer after sonication. The result of experiments related to sonication time and intensity showed that with increasing time of sonication or intensity, the absorbance is increased. It has been shown that the absorbance for continuous mode is remarkably higher than for pulsing mode (p-value<0.05). Also results show that with increasing the duty cycles of pulsed field, the inertial cavitation activity is increased. With compensation of sonication time or intensity in different duty cycles, no significant absorbance difference were observed unless 20% duty cycle. A significant correlation between the absorbance and fluorescence intensities (count) at different intensity (R=0.971), different sonication time (R=0.999) and different duty cycle (R=0.967) were observed (p-value<0.05). It is concluded that the sonication parameters having important influences on reactive radical production. These results suggest that there is a correlation between iodide dosimetry and terephthalic acid dosimetry to examine the acoustic cavitation activity in ultrasound field.

Studies on recovery of uranium from fluoride matrix employing sonochemistry

Application of power ultrasound in chemical processes is recognized as an effective tool to solve many industrial problems encountered in processes involved in nuclear industry, particularly, digestion and leaching steps. In addition, problems related to radiological safety are the most important factors to be considered, when handling radioactive materials. Sonochemical processes, due to relatively low temperature operations, are attractive in this regards. Further they are eco-friendly and economical as well. Hence, sonochemical studies were taken up for the removal of uranium from fluoride containing matrix. Dissolution studies were carried out in nitric acid medium, in a 5 L capacity tank type sono-reactor, operating at frequency and power of 22 ± 3 kHz and 150 W respectively. The parameters studied were concentration of HNO3, temperature of water-bath, choice of purged gas (air/oxygen) and flow rate of purged gas passed. Experiments were also carried out to study the amount of fluoride matrix dissolved. Enhancement with US was 76 to 91 % for U removal from MgF2 slag in 2 M HNO3. The prime advantage achieved is the reduction in the reaction time. Other advantages are minimizing labor, remotisation of operations to reduce radiation exposure, use of less acid and accordingly lesser effluent for treatment before disposal.

Susonence – a new multi-partner project developing advanced sonochemical processes to reduce chemical usage and decrease waste in the PCB and metal finishing industries

Susonence – a new multi-partner project developing advanced sonochemical processes to reduce chemical usage and decrease waste in the PCB and metal finishing industries

Treatment Methods for the Remediation of Amines: A Review

Various organic amines, most of which both toxic and carcinogenic, are being used extensively worldwide in the syntheses of azo-dyes, polyurethane, pesticides, nylon and many other nitro-aromatics. However, the uncontrolled discharge of these products, back into the environment, releases many primary or intermediate products with similar or even worse levels of toxicity. Therefore, knowledge of the degradation and complete mineralization of these amines, using best techniques with optimum efficiency, is needed. This review is aimed at summarizing the existing studies used for the degradation of amines, employing techniques, such as; biodegradation, thermal, chemical, electrochemical, photochemical, photocatalytic, sonochemical, sono-photo catalytic and sono-ozonation processes. The reactor design for the large scale degradation with optimum efficacy has also been discussed besides attempting a structural correlation to save the environment from such chemical hazards.

Adsorption and Efficient Decomposition of Perfluoro Compounds at Plasma–Water Interface

Perfluorooctane sulfonic acid (PFOS) is an environmentally harmful and persistent substance, and thus, effluent controls have been applied. The decomposition of PFOS in water using plasma attached to the water surface has been successfully performed, and the resulting energy efficiency is relatively high compared to that of other methods such as sonochemical processes. The estimation of the amount of PFOS adsorbing to the plasma-water interface showed much higher mole fraction of PFOS (6.0 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ) than that in bulk water (1.8 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> ) at a PFOS bulk concentration of 50 mg/L. Thus, the plasma can effectively react with PFOS at the water surface and exhibits high energy efficiency.

Thermolysis preparation of zinc(II) oxide nanoparticles from a new micro-rods one-dimensional zinc(II) coordination polymer synthesized by ultrasonic method

The reaction of the zinc(II) acetate and 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpdb) in presence of perchlorate anions produces a new one-dimensional coordination polymer, {[Zn(μ-3-bpdb)(3-bpdb)2(H2O)2](ClO4)2·3-bpdb}n (1). The compound 1 has been characterized by IR, 1HNMR and 13CNMR spectroscopies. The single crystal X-ray data shows an infinite one-dimensional structure that grows in two- and three-dimensions by hydrogen bonding and π–π stacking. The compound 1 also has been synthesized at micro-size by sonochemical processes and characterized by IR and X-ray powder diffraction (XRD). The scanning electron microscopy (SEM) shows compound 1 has been grown as micro-rod morphology. The thermal stabilities at bulk and micro-size scale were studied by thermal gravimetric (TG) and differential thermal analysis (DTA). The ZnO nanoparticles were obtained by direct calcination at 400°C under air atmosphere and by thermolysis in oleic acid at 200°C. The obtained zinc(II) oxide nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Global parameter of ultrasound exploitation (GPUE) in the reactors for wastewater treatment by sono-Fenton oxidation

Modeling of the sonochemical reactors presents a great challenge due to issues related to the experimental investigation and description of the primary effects of the ultrasound. The main idea proposed in this work was to establish an algorithm consisting of the viable laboratory analyses and basic elements of chemical reaction engineering. In this paper, a novel modeling approach is presented. Proposed approach is characterized by the following; ultrasound was investigated as an auxiliary source of energy and the kinetic constants determined for the basic oxidation reactions, i.e. Fenton type oxidation were treated as independent of the ultrasound. Sonochemical effectiveness factor is expressed as a global parameter of the ultrasound exploitation (GPUE) that was introduced in the kinetic model as the e US factor. Factor e US is modeled as a function of employed frequency, actual power of the transducer, portion of the cavitationally active zone, i.e. dimensionless active volume and the average temperature in the reactor. Lumped system has been assumed. In order to obtain all the necessary data, the experimental study included different sets of experiments. The kinetics of the sonochemical processes, e.g. US/Fe 2+/H 2O 2, US/Fe 2+/ S 2 O 8 2 - , US/Fe 2+/ HSO 5 - was investigated in the term of mineralization of model wastewaters containing different types of organic pollutants. The Weissler dosimetry and peroxodisulfate decomposition upon sonication, were used to facilitate the determination of e US . They follow zero order kinetics, thus can be used as a model reaction to reflect all the primary effects of ultrasound and to establish the empirical correlation for e US calculation. Finally, GPUE has been introduced in the adequate kinetic models and the overall model was validated.

Degradation of Diethyl Phthalate by Sono-Fenton Process and its Dependence on the Power Density

The first-order rate constants of diethyl phthalate (DEP) degradation by sonochemical, Fenton and sono-Fenton processes were compared, and the synergistic effect of the combined sono-Fenton process and the dependence of the degradation rate on the power density (80, 180, and 330 W L-1) were investigated. The rate constants for the individual sonochemical and Fenton processes were 10-3 to 10-2 and 1.02 ×10-2 min-1, respectively. The synergy from the combined process increased significantly as the applied power density increased, and it was 1.97 with the input of ultrasonic energy of 330 W L-1. This increase was attributed to the higher efficiency of hydroxyl radical production from several pathways. The relationship between the degradation rate constant and power density was linear because the cavitation rate increased with increasing power level of the applied ultrasound.

Sonolysis of Short-Chain Organic Dicarboxylic Acid Solutions

Sonolyses of C4 (carbon number 4) dicarboxylic acids (succinic acid, maleic acid, and fumaric acid) were performed in aqueous solution. They changed one into the other during sonication, affording carbon-number-conserving transformations. Maleic acid and fumaric acid were produced from saccinic acid by dehydrogenation. Furthermore, malic acid and tartaric acid were obtained by hydroxylation. The sonochemical reaction processes are discussed in terms of the time dependences of products and the addition of radical scavengers. In addition, mutual isomerization of fumaric acid and maleic acid was observed during sonication without the use of mediators.

Sonolysis of Short-Chain Organic Dicarboxylic Acid Solutions

Sonolyses of C4 (carbon number 4) dicarboxylic acids (succinic acid, maleic acid, and fumaric acid) were performed in aqueous solution. They changed one into the other during sonication, affording carbon-number-conserving transformations. Maleic acid and fumaric acid were produced from saccinic acid by dehydrogenation. Furthermore, malic acid and tartaric acid were obtained by hydroxylation. The sonochemical reaction processes are discussed in terms of the time dependences of products and the addition of radical scavengers. In addition, mutual isomerization of fumaric acid and maleic acid was observed during sonication without the use of mediators.

ChemInform Abstract: Potential Applications of Sonochemistry in Spent Nuclear Fuel Reprocessing: A Short Review

AbstractReview: 40 refs.