超声-MnO2协同降解偶氮染料酸性红B

研究了MnO2、超声(US)单独作用和MnO2 US联合作用降解偶氯染料酸性红B(ARB)的情况。随着溶液pH的降低，ARB脱色率逐渐提高。SO4^2-、NO3^-与染料分子在MnO2表面发生竞争吸附。单独采用超声(50kHz)，对于染料无任何降解作用。当采用MnO2 US联合作用时，二者产生协同效应，ARB脱色率及TOC去除率明显上升。经过4h超声处理后，MnO2平均粒径由47．5μm变为3．19μm，并且产生大量纳米级MnO2颗粒，提高了MnO2的反应活性。     

Enhanced sonochemical decomposition of 1,4-dioxane by ferrous iron

The enhanced ultrasonic decomposition of 1,4-dioxane by the addition of ferrous iron (Fe(II)) was investigated at 205, 358, 618, and 1071 kHz. The total organic carbon (TOC) remaining was also determined at each frequency. Addition of Fe(II) improved the 1,4-dioxane decomposition rate and mineralization efficiency at all frequencies studied. A nearly four-fold increase of the rate constant was observed at the optimal Fe(II) concentration and a frequency of 205 kHz. In the presence and absence of the iron, the fastest overall degradation and mineralization of 1,4-dioxane took place at 358 kHz where 95% of the initial 1,4-dioxane was removed after 50 min. Finally, although reduced, the ultrasonic decomposition of 1,4-dioxane was still significant at all frequencies in the presence of the hydroxyl radical scavenger bicarbonate.     

The mechanism of cavitation-induced polymer scission; experimental and computational verification

In this paper we describe qualitatively and quantitatively the non-random scission of polymers by ultrasound. Scission experiments have been performed using monodisperse polymethyl methacrylate dissolved in methyl methacrylate, showing that fracture occurs close to the center of the polymer chain. A mechanism is proposed for this non-random fracture, from which it can be concluded that complete stretching of the polymer chains is required before breakage can occur. The developed model, which is a combination of strain rate and drag force calculations, predicts a limiting molecular weight, which has experimentally been confirmed. The scission rate depends almost quadratically on the molecular weight, which is derived by modeling the experimental time-dependent molecular weight distributions. This dependence supports the requirement of complete stretching of the polymer chain before breakage. The developed degradation model is also capable to describe the effects of various process variables on cavitation-induced polymer scission.     

Sonochemical Functionalization of Cotton and Non-Woven Fabrics with Bio-Inspired Self-Assembled Nanostructures

Cotton and non-woven fabrics are commonly used for medical applications such as wound dressing. In recent years, there has been a growing interest in developing functionalized fabrics that allow the sustained release of active molecules for large-scale production. However, several limitations of currently used technologies restrict the ability to form durable fabrics with functional coatings. Herein, using a sonochemical process, we successfully deposited diphenylalanine (FF) peptide nanotubes on cotton and non-woven fabrics. FF peptide nanotubes were loaded with curcumin, an antimicrobial and anti-inflammatory agent. The structure of the fabric decorated with nanotubes was studied by electron microscopy, and the sustained release of curcumin was demonstrated using absorbance measurements. Sonication duration was positively correlated with the deposition of the nanotubes onto the fabrics’ fibers as well as the retention of the curcumin within the FF nanotubes. These results suggest that the sonochemical process may be used for large-scale fabrication of functionalized commercial fabrics.     

Sonochemical synthesis of highly monodispersed and size controllable Ag nanoparticles in ethanol solution

Highly monodispersed Ag nanoparticles (NPs) were prepared by a sonochemical method, in which Ag⁺ in an ethanol solution of AgNO₃ was reduced by ultrasound irradiation in the presence of benzyl mercaptan without the additional step of introducing other reducing reagents or protective reagents. In addition to the stabilizing effect, benzyl mercaptan remarkably enhanced the reduction rate, probably due to the thermal decomposition that occurs at the interfacial region between cavitation bubbles and bulk solution and provides reducing radicals. More importantly, the size of Ag NPs can be controlled by simply tuning the initial molar ratio of benzyl mercaptan to Ag, which was confirmed by transmission electron microscopy and ultraviolet-visible absorption spectrometry, as well as X-ray diffraction.     

Sonoelectrochemical (20 kHz) production of platinum nanoparticles from aqueous solutions

The present work describes the production of platinum nanoparticles from aqueous chloroplatinic solutions in the presence of low-frequency high-power ultrasound (20 kHz) on titanium alloy electrodes. The production of this new type of Pt nanoparticles was performed galvanostatically at (298 ± 1) K using a newly designed experimental set-up and ‘sonoelectrode’ producing ultrasonic pulses triggered and followed immediately by short applied current pulses. From galvanostatic studies, it was shown that Pt mean grain size ranging from 11 to 15 nm was produced. Morphological and structural studies of the produced nanoparticles were performed by TEM, SEM, XRD and SAED and showed that Pt nanoaggregates were predominantly formed, with no redissolution of the nanoaggregates. Globular clusters had a mean size ranging between 100 and 200 nm which in turn aggregated and built complex structures.     

Sonochemical synthesis of conducting polymer-metal nanoparticles nanocomposite

Colloidal dispersions of hybrid nanocomposite composed of polypyrrole (PPy) and gold nanoparticles (Au-NPs) or platinum nanoparticles (Pt-NPs) were prepared by a sonochemical method, in which Au ion and pyrrole monomer in an aqueous solution were reduced and oxidized, respectively, by ultrasonic irradiation in the presence of sodium dodecyl sulfate (SDS). The formation of PPy on the surface of Au-NPs or Pt-NPs is confirmed by UV-vis and transmission electron microscopy (TEM) images.     

Review on Greener and Safer Synthesis of Nitro Compounds

The review describes the recent developments in the green synthetic methods of nitro compounds involving environmentally benign approaches such as, use of solid‐supported reagents, microwave‐assisted reactions, ionic liquids, ultrasound assisted nitration reactions, gas phase nitration and vapor phase nitration.     

Synthesis of cadmium(II) hydroxide, cadmium(II) carbonate and cadmium(II) oxide nanoparticles; investigation of intermediate products

Sonochemical and hydrothermal routes have been used in different conditions for preparation of CdCO₃ and Cd(OH)₂ nanoparticles at air and inert atmospheres, respectively. The CdO nanoparticles were obtained by heating of CdCO₃ and Cd(OH)₂ nanoparticles at 400 °C. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) microscopy have been used to characterize the nanoparticles. The XRD results of intermediate products showed that the origin of CdCO₃ is CO₂ from air atmosphere.     

A physical insight into sonochemical emulsion polymerization with cavitation bubble dynamics

This paper tries to explain the physical features of the sonochemical emulsion polymerization process by coupling experiments with different conditions (such as monomer type, saturation level of the medium and the type of bubbling gas) with a mathematical model for the radial motion of cavitation bubble. Experiments have been performed without any added chemical initiator or surfactant. Time variation of the mean size and size distribution of polymer particles in the emulsion have been used as a measure for the analysis. This measure is found to be governed by various parameters such as rate of radical production from the cavitation bubbles, magnitude of the microturbulence and shock waves produced by the cavitation bubbles, glass transition temperature of polymer and the population density of polymer particles. The relative magnitudes of these parameters vary significantly with the experimental conditions. This variation has been explained on the basis of results of simulation of radial motion of cavitation bubble. It is revealed that the mean particle size and size distribution of particles are manifestation of simultaneous and resultant influence of these parameters.