Sonochemical Treatment Research Articles

Analysis of catalytic sites in FeY zeolite prepared by sono-assisted exchange of iron (II) ions

In the refining industry, Y-type faujasite (FAU) plays an irreplaceable role, being widely used to convert crude oil into more valuable products such as gasoline. However, the demand for fuels and chemicals stimulates the search for alternatives, showing the applications of FAU beyond producing value-added chemicals from petroleum-based derivatives. These alternative applications are further enhanced from active sites that emerge in zeolites when iron is incorporated by a sonochemical treatment. Given that ultrasonic irradiation promotes mass transfer, uniform coverage of active sites is expected to produce more efficient catalysts. Likewise, Fe-zeolites catalyze a wide range of reactions in mild conditions, linked to the research of bio-refinery, biomimicry and environmental remediation. This work explores the potential of a Fe-Y zeolite prepared by a sono-assisted ion exchange method in different applications: biomass conversion (lactose hydrolysis), enzyme mimetic materials (partial oxidation of benzene to phenol) and transformation of renewable energy (photodegradation of nitrobenzene and rhodamine B). The modification of FAU was performed at different sonication times 5, 15, 30 and 120 min and characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, magnetic and non-magnetic thermogravimetric analysis (MTGA and TGA), zeta potential (ζ), Fourier-transformed Infrared (ATR-FTIR), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). Finding that the modification of zeolite Y with Fe species enhances its activity for the tested applications, owing their catalytic activity primarily to α-Fe (II) sites. Presenting the sono-assisted ion exchange method as an alternative for introducing Fe species and enhancing the catalytic activity of zeolites.

Ambient Deposition of Single Atoms for Enhancement of Nanostructured Metal Oxide Electrode Catalytic Performance

Single-atom decoration represents cutting-edge technology for enhancing heterogeneous catalysis by utilizing the unique capabilities of catalysts at the atomic level. However, the high surface energy of single atoms often causes them to aggregate, forming nanoparticles [1]. To address this challenge, we first modify the surface structure by synthesizing nanostructured support layers, such as TiO2 nanotubes, TiO2 nanosheets, and NiO nanosponge. Especially TiO2 nanotubes and NiO nanosponge pose relevant support layers due to their favorable attributes, including a high surface-to-volume ratio, abundance, and excellent chemical stability, while TiO2 nanosheets serve as model system. Vertically aligned, well-ordered, self-organized oxide nanostructures can be conveniently fabricated through anodization, allowing precise control over the geometry of the nanotubes and nanopores [2,3]. Well-defined atomic-scale defects on the surface of the supports are generated to immobilize single-atom co-catalysts. Therefore, defect engineering techniques typically require high-temperature thermal reduction. We present more gentle defect-engineering approaches, including room-temperature sonochemical treatment or UV-light irradiation. By combining these approaches, we are able to effectively trap Pt and Ir single atoms.We present a direct method utilizing UV-light radiation to induce point defects, specifically Ti3+ and oxygen vacancies (VO) onto the surface of TiO2 nanosheets and efficiently decorate them with Pt single atoms [4]. Our findings demonstrate that sonochemically treated TiO2 nanotubes provide a remarkable substrate for single-atom decoration from dilute solutions, resulting in promising performance in H2 evolution catalysis and renewable energy conversion. Additionally, the role of V single-atom decoration in ultrasonic treatment of support materials is investigated.Thermal annealing in a reductive atmosphere induces the formation of numerous defects, facilitating the anchoring of single Ir atoms onto the surface of annealed NiO nanostructures. Additionally, the novel ultrasound-driven method stabilizes these Ir atoms within the porous structure. By employing both approaches, we effectively trap Ir single atoms, thereby enhancing the efficiency of the oxygen evolution reaction in electrocatalysis [5].The characterization of the electrodes is conducted using microscopy techniques (FESEM, TEM, and HAADF-STEM) and spectroscopy (XPS and ToF-SIMS) [6]. Gas chromatography is employed to evaluate the H2 photocatalytic performance of TiO2 electrodes, while linear sweep voltammetry is utilized to assess the H2 and O2 electrochemical activity of NiO electrodes [5]. Our findings highlight the significant enhancement of photo- and electrocatalytic efficiency of nanostructured oxide electrodes modified with highly stable single-atom co-catalysts by gentle treatments.

Fabrication of Strontium Molybdate with Functionalized Carbon Nanotubes for Electrochemical Determination of Antipyretic Drug-Acetaminophen.

In recent years, there has been a significant interest in the advancement of electrochemical sensing platforms to detect antipyretic drugs with high sensitivity and selectivity. The electrochemical determination of acetaminophen (PCT) was studied with strontium molybdate with a functionalized carbon nanotube (SrMoO4@f-CNF) nanocomposite. The SrMoO4@f-CNF nanocomposite was produced by a facial hydrothermal followed by sonochemical treatment, resulting in a significant enhancement in the PCT determination. The sonochemical process was applied to incorporate SrMoO4 nanoparticles over f-CNF, enabling a network-like structure. Moreover, the produced SrMoO4@f-CNF composite structural, morphological, and spectroscopic properties were confirmed with XRD, TEM, and XPS characterizations. The synergistic effect between SrMoO4 and f-CNF contributes to the lowering of the charge transfer resistance (Rct=85 Ω·cm2), a redox potential of Epc=0.15 V and Epa=0.30 V (vs. Ag/AgCl), and a significant limit of detection (1.2 nM) with a wide response range of 0.01-28.48 µM towards the PCT determination. The proposed SrMoO4@f-CNF sensor was studied with differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques and demonstrated remarkable electrochemical properties with a good recovery range in real-sample analysis.

A Review on Sonochemical Treatment of Dye Molecules

The use of ultrasound is a very effective and suitable process for the degradation of harmful dyes. In order to elucidate the degradation mechanism, numerous studies have examined the breakdown of dye molecules in aqueous medium with different additives using ultrasonic irradiation. In this review, the basic principle of sonochemical treatment and the effect of different parameters such as pH, irradiation time, different additives like NaCl, Na2SO4, CCl4, H2O2, ZnO nanoparticle etc. on sonolytic degradation of the organic dyes are discussed. From the studies it is concluded that the acidic condition is favorable for most of the dye degradation. Assessing the results of earlier studies we have also found that the aforementioned additives aided the degradation of dye molecules depending on their amount used in sonication with relatively higher or lower extent. Therefore, dye molecule from environment especially from waste water can be effectively reduced by using sonochemical irradiation process.

Efficient H2O2 -sonochemical treatment of Penicillin G in water: Optimization, DI-HRMS ultra-trace by-products analysis, and degradation pathways

Due to widespread usage of antibiotics, the possibility of surface and groundwater contamination with such pollutants has significantly increased over the years as such antibiotics have been widely reported in water bodies. This study reports on the elimination of toxic antibiotic Penicillin G (PG) from wastewaters sources via the sonochemical process in the presence of hydrogen peroxide (H2O2) as well as to identify the degradation by-products. The effect of initial pH, pollutant dosage and presence of hydrogen peroxide on the degradability was examined. Response Surface Methodology (RSM) was used to model the sonochemical process with high correlation of (R2= 0.9784) and predictions agreed well with the experimental results. Box-Behnken Design (BBD) and RSM equations were used to determine the optimal values of experimental conditions for the PG degradation at the optimum conditions: PG dose of 20 mgL−1, pH 3.4 and hydrogen peroxide (H2O2) concentration of 600 mgL−1. Under the optimized conditions, removal efficiency reached 97% and by-products formed during sonochemical degradation were identified via QuEChERS method (Quick, Easy, Cheap, Effective, Rugged, and Safe), while the pre-concentration by evaporation was followed by the direct infusion-high resolution mass spectrometry technique (DI-HRMS). This is the first study to report a detailed investigation on PG degradation products under the sonochemical treatment combined with QuEChERS method to DI-HRMS techniques. Such advanced methods allowed us to determine the analyte substance found in water at low concentrations (ng L−1). The seven by-products have been detected where two possible degradation pathways were proposed with a resulting total elimination of PG.

Effect of lightly substituted samarium ions on the structural, optical, magnetic and dielectric properties of the sonochemically synthesized M-type Sr-hexaferrite nanoparticles

In this study, the role of sonochemical treatment followed by a combustion process adopted for the synthesis of SrSmxFe12-xO19 (x = 0.01 to 0.03) hexaferrites. We have investigated effect of lightly Sm substitutions on structural, magnetic, optical and dielectric properties in Strontium hexaferrites. X-ray diffraction analysis show M as major phase with impurity. The FTIR analysis shows that the value of force constant increased on both sides (tetra hederal and octa hederal) with the increase of samarium content. The band gap was calculated using Tauc method from UV–Visible spectra. Result shows that as the samarium content increases from x = 0.01 to 0.03 the band gap gradually increases from 2.50 eV 2.91 eV respectively. The surface morphology of prepared Sm substituted SrM nanoparticles was examined using field emission scanning electron microscopy, an average particle size was found to 301 nm, 254 nm, and 285 nm for x = 0.01, 0.02, and 0.03 compositions respectively. High values of Ms (53.104 emu/g.) and Mr (29.0 emu/g) observed in x = 0.03 sample with low Hc of 53.104 Oe. Mr/Ms values of all samples are >0.5 show that of formed hexaferrite nanoparticles possess single magnetic domain structure. The Sm-doped of the SrFe12O19 compound exhibits a low dielectric constant (ε′) ∼ 20 at low frequencies, while it increased with increasing temperature and reached 100 when the Sm content was 0.01, but less than 150 in x = 0.02 and 0.03. The temperature and frequency-dependent dielectric constant confirmed the contributions of different polarization mechanisms.

Sonochemical treatment of packaging materials for prolonging fresh produce shelf life

Packaging bags made of polyethylene (PE) were sonochemically coated with edible antibacterial nanoparticles of chitosan (CS). In this work, the nanoparticles (NPs) were deposited on the surface of PE packaging bags by applying sonication waves on an acetic solution of chitosan. The characterization of CS NPs and PE bags was conducted by physicochemical techniques. The results showed that the coated bags had longer freshness than the uncoated ones. Furthermore, the characterization of cucumber, mushroom, and garlic placed into coated and uncoated PE bags was conducted by monitoring various parameters such as mass loss, total soluble solids, pH, and visual inspection. The study revealed that the PE bags coated with CS NPs showed a noticeable result in extending the shelf life of fresh produce. Finally, the antibacterial activity of PE bags was evaluated against various bacterial species. Hence, the PE bags coated with CS NPs could be a promising candidate for elongating the shelf life of packaged fresh produce.

Влияние сонохимического воздействия на свойства пшеничного крахмала

The food industry uses sonochemical treatment as part of emulsification, homogenization, and dispersion, as well as to modify viscosity and structure. Starch is one of the most common food ingredients, both as a raw material or a property-modifying additive. The research objective was to study the effect of sonochemical action on the structural and mechanical properties of wheat starch suspensions.
 The study involved suspension samples with 10% wheat starch. The suspension samples were treated with ultrasound using an ultrasonic device Volna-M model UZTA-1/22-OM or in an ultrasonic bath (22 kHz; 100, 150, 300, and 400 W). The treatment time was 15 and 30 min. The rheological, physical, and textural properties were recorded according to conventional methods before and after the treatment.
 The ultrasonic treatment caused mechanical damage to the starch, making it more accessible to moisture when heated. As a result, the structural, mechanical, and rheological properties of starch suspensions changed. All the studied suspensions had a non-Newtonian character. The ultrasonic treatment increased their consistency coefficient from 28.12 to 152.75 µPa·s. The gelatinization temperature of all experimental starch suspensions dropped from 63.4 to 61.0°C. The short high-power ultrasound treatment reduced the strength of gels to 1.25 N compared to that of native starch gel (4.28 N).
 In this research, the ultrasound treatment of wheat starch suspensions modified the structural, mechanical, and rheological profile of starch and proved able to replace some conventional starch modification procedures, i.e., chemical, physical, or enzymatic. The new approach can provide modified starches of a preset quality while reducing energy costs and processing time.

Black titania by sonochemistry: A critical evaluation of existing methods

In the field of photocatalysis, the fabrication of black titania is a booming topic, as it offers a system with improved solar light harvesting properties and increased overall efficiency. The darkening of white TiO2 powders can be ascribed to surface hydroxylation, oxygen vacancies, Ti3+ centres, or a combination thereof. A handful of studies suggests these defects can be conveniently introduced by acoustic cavitation, generated during sonochemical treatment of pristine TiO2 powders. In reproducing these studies, P25 TiO2 samples were ultrasonicated for various hours with a power density of 8000 W/L, resulting in powders that indeed became gradually darker with increasing sonication time. However, HAADF–STEM revealed that extensive erosion of the sonotrode tip took place and contaminated the samples, which appeared to be the primary reason for the observed colour change. This was confirmed by UV–Vis DRS and DRIFTS, that showed no significant alteration of the catalyst surface after sonication. EPR measurements showed that only an insignificant fraction of Ti3+ centres were produced, far less than in a TiO2 sample that was chemically reduced with NaBH4. No evidence of the presence oxygen vacancies could be found. The enhanced photocatalytic activities of ultrasonicated materials reported in literature can therefore not be ascribed to the synthesis of actual black (defected) TiO2, but rather to specific changes in morphology as a result of acoustic cavitation. Also, this study underlines the importance of considering probe erosion in sonochemical catalyst synthesis, which is an unavoidable side effect that can have an important impact on the catalyst appearance, properties and performance.

Room-temperature defect-engineered titania: An efficient platform for Pt single atom decoration for photocatalytic H2 evolution

Single-atom (SA) decoration represents the forefront of technological advancements in heterogeneous catalysis, harnessing the exceptional performance of catalysts at the atomic level. However, the high surface energy of isolated atoms often leads to agglomeration, resulting in the formation of nanoparticles. To address this challenge, trapping single atoms within surface defects has emerged as an effective strategy for atom immobilization. Conventional defect engineering techniques, such as high-temperature thermal reduction, suffer from adverse effects, such as sintering of the support material. In this study, we introduce a novel and facile room-temperature sonochemical method to induce well-defined atomic-scale defects on the surface of highly active TiO2 nanosheets, predominantly exposing the (001) facet. By introducing a highly diluted Pt precursor to the ultrasonicated nanosheet slurry, isolated Pt atoms were selectively trapped within freshly formed defects. Remarkably, the resulting Pt single atom decorated samples exhibit a striking 100-fold increase in photocatalytic H2 evolution compared to pristine TiO2 nanosheets. Notably, we demonstrate that the density of the generated defects and the loading of Pt single atoms can be precisely tailored by adjusting the sonication time. Atomic-scale characterization, complemented by density functional theory (DFT) calculations, provides compelling evidence of the strong bonding between Pt single atoms and the defects generated via sonochemical treatment. Our findings offer a promising approach for defect engineering and SA decoration on a larger scale, underscoring the significant potential of this room-temperature technique for heterogeneous catalysis.

Impact of a Sonochemical Approach to the Structural and Antioxidant Activity of Brown Algae (Fucoidan) Using the Box–Behnken Design Method

A fucoidan discovered in the plant Fucus vesiculosus, which lowered the molecular weight of fucoidan, was ideal for its application in the pharmaceutical and food sectors. The aim was to study the impact of ultrasound process parameters on the molecular weight, structure, and antioxidant activity of fucoidan. For optimization of sonochemical process parameters such as temperature, sonication time, and power (intensity), Box–Behnken design (BBD) through the response surface method (RSM) at fixed fucoidan concentrations was compared with a normal process. The outcomes demonstrated that sonochemical treatment significantly decreased molecular weight (Mw) to 318 kDa compared to the control process (815 kDa). Antioxidant activity tests revealed that the sonication treatment significantly increased antioxidant activity (88.9% compared to 65.3% with the control process). Through use of the BBD model, we found that the ideal conditions for degradation of fucoidan were a temperature of 33 °C, sonication time of 40 min, and sonication power of 102.5 W/cm2. Under these conditions, the quadratic model was fitted and the experimental values for Mw and antioxidant activity (318 kDa and 87.4%) were close to the predicated values (316 kDa and 87.9%). According to the findings, sonication treatment is a useful method for lowering fucoidan levels with no observable changes in the monosaccharide units of fucoidan through scanning electron microscope, X-Ray diffraction, and Fourier-transform infrared (FTIR) analysis.

Integrated LaFeO3/rGO nanocomposite for the sensitive electrochemical detection of antibiotic drug metronidazole in urine and milk samples

Metronidazole (MTZ) is a nitroimidazole antibiotic commonly used to treat bacterial infections, but its residues in food products may pose teratogenic, mutagenic, and carcinogenic risks to human health. Hence, monitoring MTZ in food and human samples is essential. In this study, we developed a glassy carbon electrode (GCE) modified with lanthanum ferrite (LFO) integrated with reduced graphene oxide (rGO) nanocomposite for the electrochemical detection of MTZ. The engineered nanocomposite was prepared by the sonochemical treatment and then systematically characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The modified LFO/rGO/GCE exhibits excellent electrochemical performance, which is mainly owing to the high surface areas, conductivity, and synergistic effects of LFO and rGO. Using the DPV method, the LFO/rGO/GCE sensor showed a wide linear range of 0.2–1221 µM and a low LOD of 0.048 µM for MTZ detection. The modified sensor selectivity was confirmed with biological species and metal compounds. In addition, the developed sensor demonstrated good stability, reproducibility, and repeatability toward MTZ. Satisfactory recoveries were obtained for MTZ detection in human urine and milk samples using the fabricated LFO/rGO/GCE sensor.

Sonochemical transportation technology high viscous oil

The work is devoted to one of the urgent problems of the oil and gas complex - the transportation of high-viscosity oils. The object of the study was the high-viscosity high-sulphur mixed oil of the Ashalchinskoye field. The sonochemical treatment of oil made it possible to reduce the effective viscosity by 35-40% and the pour point by 15-20 °C. Pilot tests of the developed unit and sonochemical technology have shown the possibility of reducing the load on pumping stations of main pipelines, reducing the number of hot oil pumping stations, and reducing the amount of emissions of organic sulfur compounds into the atmosphere. Keywords: high-viscosity oil; petroleum dispersed systems; ultrasound; pour point depres-sants; sonochemical effect; effective viscosity; pour point.

Sonochemical Degradation of Gelatin Methacryloyl to Control Viscoelasticity for Inkjet Bioprinting.

Inkjet printing enables the mimicry of the microenvironment of natural complex tissues by patterning cells and hydrogels at a high resolution. However, the polymer content of an inkjet-printable bioink is limited as it leads to strong viscoelasticity in the inkjet nozzle. Here it is demonstrated that sonochemical treatment controls the viscoelasticity of a gelatin methacryloyl (GelMA) based bioink by shortening the length of polymer chains without causing chemical destruction of the methacryloyl groups. The rheological properties of treated GelMA inks are evaluated by a piezo-axial vibrator over a wide range of frequencies between 10 and 10000Hz. This approach enables to effectively increase the maximum printable polymer concentration from 3% to 10%. Then it is studied how the sonochemical treatment effectively controls the microstructure and mechanical properties of GelMA hydrogel constructs after crosslinking while maintaining its fluid properties within the printable range. The control of mechanical properties of GelMA hydrogels can lead fibroblasts more spreading on the hydrogels. A 3D cell-laden multilayered hydrogel constructs containing layers with different physical properties is fabrictated by using high-resolution inkjet printing. The sonochemical treatment delivers a new path to inkjet bioprinting to build microarchitectures with various physical properties by expanding the range of applicable bioinks.

Photovoltaic Performance of Si and SiGe Surfaces Sonochemically Activated in Dichloromethane

Aims: To activate Si and SiGe surfaces by employing the sonochemical treatment at different operating frequencies in dichloromethane to improve the surface photovoltage signal. Background: To produce integrated electronic devices, one needs to achieve low surface and interface trap densities. In this respect, placing a passivating thin layer on Si and Ge surfaces, which saturates the electronic levels of traps and therefore affects the carrier recombination velocities at the surface, is of great interest. Objective: To demonstrate that the effectiveness of the treatment of Si and SiGe surfaces depends on the ultrasonic frequency used. Methods: Photovoltaic transients, electron microscopy, EDX spectroscopy. Result: The surface photovoltage (SPV) decay curves can be divided into rapid (τ_1) and slow (τ_2) components. The sonication effect on the SPV is different for the treatment done at about 25 and 400 kHz. The SPV signal in Si gradually increases with increasing lower-frequency sonication time, whereas the SPV enhancement on SiGe is somewhat smaller. Increasing the sonication time increases the amplitude of the τ_2 component in Si. In SiGe, the lower-frequency sonication quenches the τ_2 component yielding a nearly single-exponential decay form. This trend is even more pronounced at the higher-frequency sonication. Conclusion: The sonochemical treatments greatly intensify the formation of CxHy–Si and CxHy–Ge bonds on Si and Si1-xGex surfaces, resulting in increased SPV signals and prolonged SPV decay times. These results demonstrate that sonochemical treatment is a more effective technique to obtain stable highly passivated Si and Si1-xGex surfaces in comparison with wet chemical treatments in hydrocarbon solutions.

Methods involved in the treatment of four representative pharmaceuticals in hospital wastewater using sonochemical and biological processes

A primary pollution source by pharmaceuticals is hospital wastewater (HWW). Herein, the methods involved in the action of a biological system (BS, aerobic activated sludge) or a sonochemical treatment (US, 375 kHz and 30.8 W), for degrading four relevant pharmaceuticals (azithromycin, ciprofloxacin, paracetamol, and valsartan) in HWW, are shown. Before treatment of HWW, the correct performance of BS was assessed using glucose as a reference substance, monitoring oxygen consumption, and organic carbon removal. Meanwhile, for US, a preliminary test using ciprofloxacin in distilled water was carried out. The determination of risk quotients (RQ) and theoretical analyses about reactive moieties on these target substances are also presented. For both, the degradation of the pharmaceuticals and the calculation of RQ, analyses were performed by LC-MS/MS. The BS action decreased the concentration of paracetamol and valsartan by ∼96 and 86%, respectively. However, a poor action on azithromycin (2% removal) was found, whereas ciprofloxacin concentration increased ∼20%; leading to an RQ value of 1.61 (high risk) for the pharmaceuticals mixture. The analyses using a biodegradation pathway predictor (EAWAG-BDD methodology) revealed that the amide group on paracetamol and alkyl moieties on valsartan could experience aerobic biotransformations. In turn, US action decreased the concentration of the four pharmaceuticals (removals > 60% for azithromycin, ciprofloxacin, and paracetamol), diminishing the environmental risk (RQ: 0.51 for the target pharmaceuticals mixture). Atomic charge analyses (based on the electronegativity equalization method) were performed, showing that the amino-sugar on azithromycin; piperazyl ring, and double bond close to the two carbonyls on ciprofloxacin, acetamide group on paracetamol, and the alkyl moieties bonded to the amide group of valsartan are the most susceptible moieties to attacks by sonogenerated radicals. The LC-MS/MS analytical methodology, RQ calculations, and theoretical analyses allowed for determining the degrading performance of BS and US toward the target pollutants in HWW.•Biological and sonochemical treatments as useful methods for degrading 4 representative pharmaceuticals are presented.•Sonochemical treatment had higher degrading action than the biological one on the target pharmaceuticals.•Methodologies for risk environmental calculation and identification of moieties on the pharmaceuticals susceptible to radical attacks are shown.

Effect of sonochemical pretreatment of slurry depressors on sylvin flotation performance

The main source of potassium fertilizers is sylvinite ores consisting primarily of halite (NaCl), silicate and clay-carbonate slurries (clay-salt slurries). Processing of natural potash ores is mainly carried out by the flotation method, which separates KCl, NaCl, and clay-salt slurry. The research is aimed at revealing the effect of sonochemical pretreatment of the depressor reagents, CMC and starch, on dynamic viscosity, aggregate size, electrokinetic potential of these reagent solutions and sylvin flotation performance. It has been established that sonochemical treatment of depressor solutions decreases the size of aggregates of starch molecules by more than 133 times and that of aggregates of CMC molecules from 6 to 4 nm. It has been revealed that sonochemical treatment of anionic CMC solution shifts the electrokinetic potential towards the area of negative values with an increase in acoustic power, while sonochemical treatment of any acoustic power has no effect on the zeta potential of nonionic starch. It has been found that the sonochemical treatment lowers the dynamic viscosity of CMC and starch solutions: the viscosity of CMC solution at a maximum acoustic power of 420 W decreases by 44 % and the viscosity of starch solution at the same acoustic (ultrasonic) power decreases by 70 %. Furthermore, sonochemical pretreatment of sylvin flotation depressors contributes to an increase in KCl recovery and a decrease in the slurry content in the flotation concentrate. The possibility of reducing the consumption of ultrasonic treated depressor is also demonstrated. It is expedient to test the obtained findings in pilot-plant conditions.

Sonochemical oxidation and stabilization of liquid elemental mercury in water and soil

Over 3000 mercury (Hg)-contaminated sites worldwide contain liquid metallic Hg [Hg(0)l] representing a continuous source of elemental Hg(0) in the environment through volatilization and solubilization in water. Currently, there are few effective treatment technologies available to remove or sequester Hg(0)l in situ. We investigated sonochemical treatments coupled with complexing agents, polysulfide and sulfide, in oxidizing Hg(0)l and stabilizing Hg in water, soil and quartz sand. Results indicate that sonication is highly effective in breaking up and oxidizing liquid Hg(0)l beads via acoustic cavitation, particularly in the presence of polysulfide. Without complexing agents, sonication caused only minor oxidation of Hg(0)l but increased headspace gaseous Hg(0)g and dissolved Hg(0)aq in water. However, the presence of polysulfide essentially stopped Hg(0) volatilization and solubilization. As a charged polymer, polysulfide was more effective than sulfide in oxidizing Hg(0)l and subsequently stabilizing the precipitated metacinnabar (β-HgS) nanocrystals. Sonochemical treatments with sulfide yielded incomplete oxidation of Hg(0)l, likely resulting from the formation of HgS coatings on the dispersed µm-size Hg(0)l bead surfaces. Sonication with polysulfide also resulted in rapid oxidation of Hg(0)l and precipitation of HgS in quartz sand and in the Hg(0)l-contaminated soil. This research indicates that sonochemical treatment with polysulfide could be an effective means in rapidly converting Hg(0)l to insoluble HgS precipitates in water and sediments, thereby preventing its further emission and release to the environment. We suggest that future studies are performed to confirm its technical feasibility and treatment efficacy for remediation applications.

High oxygen-yield homogeneous sonophotocatalysis for water-splitting using theraphthal

Overall water splitting processes in homogeneous media using water-soluble innovative photocatalyst Theraphthal (TP) are reported. TP, having a coral-like morphology composed of 2D particles with average size 245 nm, is a Co-substituted phthalocyanine with –COONa and –COOH groups, able to generate Reactive Oxygen Species (ROS) under ultrasonic treatment and possessing antitumoral properties. Both H2 and O2 evolution under UVA irradiation of the TP aqueous solution has been observed, considerably increasing O2 generation and suppression of H2 formation in case of additional assisting with ultrasound due to the synergistic effect of the light and the sonochemical treatment. The stability of the alternative TP homogeneous photocatalysis was demonstrated after three consecutive evaluation cycles and by the analysis of its absorption spectra. The highest O2 yield obtained was superior (1,444 µmol in 3 h) to previous reports of using traditional phthalocyanines. Also, possible mechanism for water splitting processes in homogeneous media based on ROS generation on the TP surface and reversible transfer of Co2+ ↔ Co3+ is proposed.

Flexible supercapacitor with superior length and volumetric capacitance enabled by a single strand of ultra-thick carbon nanotube fiber

Fiber-shaped supercapacitors (FSSCs) based on next-generation carbon-based fibers are widely recognized as the most promising power supplies for wearable devices; however, achieving a high capacitance in weight, volume, and length simultaneously with a single fiber, which is necessary to realize practical FSSCs, has rarely been reported. Here, we show for the first time that a single ultra-thick carbon nanotube fiber (UCNTF, 10 tex) with high linear density can function as a practical electrode material in FSSCs. A series of sonochemical treatments is used to modify the internal structure and physical properties of pristine UCNTFs and to further synthesize pseudocapacitive active materials (i.e., polyaniline (PANI)). PANI in its most electrochemically useful state uniformly incorporated into purified UCNTFs with a controlled morphology and functional groups, facilitating the penetration of ions and promoting a reversible redox reaction between the electrolyte ions and the fiber. A symmetric FSSC fabricated using the prepared PANI-incorporated UCNTF exhibits a high specific capacitance of 335F/g at 1 A/g, an excellent volumetric capacitance of 523.3F cm−3, and an outstanding length capacitance of 96.5 mF cm−1 without additional fibers being added. In addition, the FSSC exhibits high flexibility (98.4 % at a bending angle of 90°) and high stability (80.1 % after 20,000 bending cycles). We believe that this first report of the preparation of an FSSC using a single CNTF, which can be conducted on an industrial scale, will open new opportunities for commercializing wearable energy storage devices.