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Advanced oxidation procedures (AOPs) refer to a variety of technical procedures that produce OH radicals to sufficiently oxidize wastewater, organic pollutant streams, and toxic effluents from industrial, hospital, pharmaceutical and municipal wastes. Through the implementation of such procedures, the (post) treatment of such waste effluents leads to products that are more susceptible to bioremediation, are less toxic and possess less pollutant load. The basic mechanism produces free OH radicals and other reactive species such as superoxide anions, hydrogen peroxide, etc. A basic classification of AOPs is presented in this short review, analyzing the processes of UV/H2O2, Fenton and photo-Fenton, ozone-based (O3) processes, photocatalysis and sonolysis from chemical and equipment points of view to clarify the nature of the reactive species in each AOP and their advantages. Finally, combined AOP implementations are favored through the literature as an efficient solution in addressing the issue of global environmental waste management.

Ultrasonic small scale flow reactors have found increasing popularity among researchers as they serve as a very useful platform for studying and controlling ultrasound mechanisms and effects. This has led to the use of these reactors for not only research purposes, but also various applications in biological, pharmaceutical and chemical processes mostly on laboratory and, in some cases, pilot scale. This review summarizes the state of the art of ultrasonic flow reactors and provides a guideline towards their design, characterization and application. Particular examples for ultrasound enhanced multiphase processes, spanning from immiscible fluid–fluid to fluid–solid systems, are provided. To conclude, challenges such as reactor efficiency and scalability are addressed.

Plastics have become indispensable in modern society; however, the proliferation of their waste has become a problem that can no longer be ignored as most plastics are not biodegradable. Depolymerization/degradation through sustainable processes in the context of the circular economy are urgent issues. The presence of multiple types of plastic materials makes it necessary to study the specific characteristics of each material. This mini-review aims to provide an overview of technological approaches and their performance for the depolymerization and/or degradation of one of the most widespread plastic materials, polypropylene (PP). The state of the art is presented, describing the most relevant technologies focusing on advanced oxidation technologies (AOT) and the results obtained so far for some of the approaches, such as ozonation, sonochemistry, or photocatalysis, with the final aim of making more sustainable the PP depolymerization/degradation process.

In this work, cerium dioxide nanostructures were synthesized in an easy sonochemical way. CeO 2 nanoparticles have received much attention in nanotechnology. CeO 2 NPs, exhibit biomimetic properties depending on their size, ratio of valency on their surface, and the ambient physico-chemical properties. Nanomedicine has emerged as a promising avenue for targeted cancer therapy, aiming to develop innovative approaches with improved efficacy and reduced side effects. Here, for the production of cerium dioxide nanostructures, a new and natural capping agent called Rosa Damascena extract was utilized, as well as ceric ammonium nitrate as a metal precursor. The results of the characterization of the oxide sample fabricated in the presence of Rosa Damascena extract demonstrated that nanostructures with a sponge-like morphology, which have a pure cubic crystal phase, were formed. The cytotoxicity effect of CeO 2 NPs on glioblastoma and neuroblastoma cell lines (T98, SHSY5Y) was studied using the MTT test; cerium oxide nanoparticles exhibited cytotoxicity effects on T98 and SHSY5Y cell lines, compared to the control. The improved cytotoxic effects can be due to the plant secondary metabolites involved in the green synthesis of NPs. Consequently, synthesized CeO 2 NPs have revealed an acceptable inhibitory impact upon cancer cell lines.

Sonochemistry is the use of ultrasonic waves in an aqueous medium, to generate acoustic cavitation. In this context, sonochemistry emerged as a focal point over the past few decades, starting as a manageable process such as a cleaning technique. Now, it is found in a wide range of applications across various chemical, physical, and biological processes, creating opportunities for analysis between these processes. Sonochemistry is a powerful and eco‐friendly technique often called “green chemistry” for less energy use, toxic reagents, and residues generation. It is increasing the number of applications achieved through the ultrasonic irradiation (USI) method. Sonochemistry has been established as a sustainable and cost‐effective alternative compared to traditional industrial methods. It promotes scientific and social well‐being, offering non‐destructive advantages, including rapid processes, improved process efficiency, enhanced product quality, and, in some cases, the retention of key product characteristics. This versatile technology has significantly contributed to the food industry, materials technology, environmental remediation, and biological research. This review is created with enthusiasm and focus on shedding light on the manifold applications of sonochemistry. It delves into this technique‘s evolution and current applications in cleaning, environmental remediation, microfluidic, biological, and medical fields. The purpose is to show the physicochemical effects and characteristics of acoustic cavitation in different processes across various fields and to demonstrate the extending application reach of sonochemistry. Also to provide insights into the prospects of this versatile technique and demonstrating that sonochemistry is an adapting system able to generate more efficient products or processes. Ultrasound irradiation is not merely a phenomenon with a singular application. Grasping the fundamentals not only facilitates comprehension of the underlying mechanisms but also elucidates the development of a green technique. This, in turn, broadens the scope of applications, fostering innovation in new systems with solutions that are more environmentally and socially friendly.

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe3O4NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe3O4@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review’s main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.

Imidazole-based compounds are a series of heterocyclic compounds that exhibit a wide range of biological and pharmaceutical activities. However, those extant syntheses using conventional protocols can be time-costly, require harsh conditions, and result in low yields. As a novel and green technique, sonochemistry has emerged as a promising method for organic synthesis with several advantages over conventional methods, including enhancing reaction rates, improving yields, and reducing the use of hazardous solvents. Contemporarily, a growing body of ultrasound-assisted reactions have been applied in the preparation of imidazole derivatives, which demonstrated greater benefits and provided a new strategy. Herein, we introduce the brief history of sonochemistry and focus on the discussion of the multifarious approaches for the synthesis of imidazole-based compounds under ultrasonic irradiation and its advantages in comparison with conventional protocols, including typical name-reactions and various sorts of catalysts in those reactions.

Sonochemistry has become increasingly important in bioengineering research, and many in vitro and in vivo bioapplications have been developed. Cytotoxicity is always a concern in its implementation. For in vivo treatments and studies, mechanical index (MI) is known to ensure biocompatibility, and even in vitro MI has been used. Because cell characteristics and acoustic phenomena differ in vitro and in vivo, we questioned using MI in vitro. The in vitro cytotoxicity of ultrasound exposure should be investigated to support the development of cutting‐edge sonochemistry. In this study, a system for irradiating cultured cells with 1–2 MHz‐range ultrasound was developed to demonstrate the invalidity of employing MI alone in vitro. The results showed that cell damage is defined by the MI, ultrasound frequency, and exposure time, which are new indices for quantifying cell damage. Furthermore, cavitation and acoustic streaming are shown to be the main scientific factors that injure cells.

This last century, the development of new medicinal molecules represents a real breakthrough in terms of humans and animal life expectancy and quality of life. However, this success is tainted by negative environmental consequences. Indeed, the synthesis of drug candidates requires the use of many chemicals, solvents, and processes that are very hazardous, toxic, energy consuming, expensive, and generates a large amount of waste. Many large pharmaceutical companies have thus moved to using green chemistry practices for drug discovery, development, and manufacturing. One of them is the use of energy-efficient activation techniques, such as ultrasound. This review summarizes the latest most representative works published on the use of ultrasound for sustainable bioactive molecules synthesis.

In the present review, the production of O radicals (oxygen atoms) in acoustic cavitation is focused. According to numerical simulations of chemical reactions inside a bubble using an ODE model which has been validated through studies of single-bubble sonochemistry, not only OH radicals but also appreciable amounts of O radicals are generated inside a heated bubble at the violent collapse by thermal dissociation of water vapor and oxygen molecules. The main oxidant created inside an air bubble is O radicals when the bubble temperature is above about 6500 K for a gaseous bubble. However, the concentration and lifetime of O radicals in the liquid water around the cavitation bubbles are unknown at present. Whether O radicals play some role in sonochemical reactions in the liquid phase, which are usually thought to be dominated by OH radicals and H2O2, should be studied in the future.