Ultrasound-assisted anodic oxidation of diuron

Ultrasound-assisted electrodeposition and synthesis of alloys and composite materials: A review

The development of electrodeposited materials with improved technological properties has been attracting the attention of researchers and companies from different industrial sectors. Many studies have demonstrated that the electrodeposition and synthesis of alloys and composite materials assisted by ultrasound may promote the de-agglomeration of particles in the electrolytic solution due to microturbulence, microjets, shock waves, and breaking of Van der Waals forces. The sonoelectrochemical technique, in which the ultrasound probe acts as a working electrode, also has been used for the formation of nanostructures in greater quantity, in addition to accelerating the electrolysis process and eliminating the reaction products on the electrode surface. Regarding the morphological aspects, the acoustic cavitation promotes the formation of smooth and uniform surfaces with incorporated particles homogeneously distributed. These changes have a direct impact on the composition and physical properties of the material, such as corrosion resistance, magnetization, wear, and microhardness. Despite the widespread use of acoustic cavitation in the synthesis of nanostructured materials, the discussion of how process variables such as acoustic power, frequency, and type of ultrasound device, as well as their effects still are scarce. In this sense, this review discusses the influence of ultrasound technology on obtaining electrodeposited coatings. The trends and challenges in this research field were reviewed from 2014 to 2019. Moreover, the effects of process variables in electrodeposition and how these ones change the technological properties of these materials were evaluated.

Use of Ultrasound as an Advanced Oxidation Process for the Degradation of Emerging Pollutants in Water

Emerging pollutants are compounds of increased environmental importance and, as such there is interest among researchers in the evaluation of their presence, continuity and elimination in different environmental matrices. The present work reviews the available scientific data on the degradation of emerging pollutants, mainly pharmaceuticals, through ultrasound, as an advanced oxidation process (AOP). This study analyzes the influence of several parameters, such as the nature of the pollutant, the ultrasonic frequency, the electrical power, the pH, the constituents of the matrix and the temperature of the solution on the efficiency of this AOP through researches previously reported in the literature. Additionally, it informs on the application of the referred process alone and/or in combination with other AOPs focusing on the treatment of domestic and industrial wastewaters containing emerging pollutants, mainly pharmaceuticals, as well as on the economic costs associated with and the future perspectives that make ultrasound a possible candidate to solve the problem of water pollution by these emerging pollutants..

In Situ Coupling of Ultrasound to Electro- and Photo-Deposition Methods for Materials Synthesis

This short review provides the current state-of-the-art of in situ coupling of ultrasound to chemical deposition methods. Synergetic action of ultrasound and light radiation or electrical fields may result in new powerful methodologies, which include sonophotodeposition and sonoelectrodeposition processes. The effect of ultrasound is explained on the basis of different physical mechanisms emerging from cavitation phenomenon. Some possible mechanisms of the interactions between ultrasound and photochemical and electrochemical processes are discussed here. The application of sonophotodeposition and sonoelectrodeposition as green energy sources in the syntheses of different nanomaterials is also reviewed.

A review on sonoelectrochemical technology as an upcoming alternative for pollutant degradation

Sonoelectrochemical process has emerged as a novel integrated technology for various applications starting from sonoelectroplating till the remediation of a wide range of contaminants. Although a promising new technology, the application of sonoelectrochemical technology for pollutant degradation are mostly on a laboratory scale, utilizing the conventional reactor configuration of the electrolytic vessel and ultrasonic horns dipped in it. This type of configuration has been believed to be responsible for its sluggish evolution with lower reproducibility, scale-up and design aspects. To achieve a major turn with an enhanced synergy, refinements in the form of optimizing the co-ordination of the governing parameters of both the technologies (e.g., power, frequency, liquid height, electrode material, electrode size, electrode gap, applied voltage, current density etc.) have been validated. Besides, in order to supplement knowledge in the already existing pool, rigorous research on the past and present status has been done. Challenges were also identified and to overcome them, critical discussions covering an overview of the progressive developments on combining the two technologies and its major applications on pollutant degradation were conducted.

Application of ultrasound in electrochemistry. An overview of mechanisms and design of experimental arrangement

An overview of possible mechanisms by which sonication can influence electrochemical processes is given. Four mechanisms are discussed: – acoustic streaming; – microstreaming and turbulence due to cavitation; – formation of microjets in the course of collapse of cavitation bubble; – shock waves; and possible effects are illustrated on several examples. The most effective process is formation of microjets,which can not only decrease diffusion layer thickness under 1 lm, but also activate (depassivate) electrode surface. Design of experimental arrangement with maximum participation of microjets is proposed. Two approaches are proposed: – focusing of ultrasound on the working electrode and reduction of energy losses by over-pressure; – ‘‘tuning” the reactor to obtain resonance, i.e. formation of stationary waves by activating reactor in itsresonant mode.

Organic Sonoelectrochemistry on Mercury Pool Electrode

So far, the influence of sonication on the electrolytic current was studied only at solid or rather miniaturized mercury electrodes. The presented paper reports on sonoelectrochemical experiments at a liquid mercury pool electrode. Two sonoelectrochemical cells have been developed and tested. It was shown that during sonication, the electrolytic current increases in a number of individual peaks representing short local enhancements of current density due to vigorous local mass transfer and instantaneous increase of fresh electrode surface. Both these effects are caused by microjets of solution formed during violent unsymmetric collapses of cavitation bubbles in the close vicinity of the electrode surface. The newly formed electrode surface and the decrease in the diffusion layer thickness were estimated and discussed. An example is presented where the sonication is used for destruction of a film of products formed during electrolysis of cysteine, that otherwise rapidly inhibits continuation of the electrode process.