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In this study, ultrasonically driven biosynthesis of zinc oxide nanoparticles (ZnO NPs) using Swietenia macrophylla seed ethyl acetate fraction (SMEAF) has been reported. X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the presence of a pure hexagonal wurtzite structure of ZnO. Field emission scanning electron microscope images revealed the formation of uniquely identifiable uniform rice-shaped biologically synthesized ZnOSMEAF particles. The particle sizes of the biosynthesized NPs ranged from 262 to 311 nm. The underlying mechanisms for the biosynthesis of ZnOSMEAF under ultrasound have been proposed based on FTIR and XRD results. The anticancer activity of the as-prepared ZnOSMEAF was investigated against HCT-116 human colon cancer cell lines via methyl thiazolyl tetrazolium assay. ZnOSMEAF exhibited significant anticancer activity against colon cancer cells with higher potency than ZnO particles prepared using the chemical method and SMEAF alone. Exposure of HCT-116 colon cancer cells to ZnOSMEAF promoted a remarkable reduction in cell viability in all the tested concentrations. This study suggests that green sonochemically induced ZnO NPs using medicinal plant extract could be a potential anticancer agent for biomedical applications.

A natural polymer-based iron oxide (Fe3O4) nanocomposite was prepared through a sonochemical-assisted precipitation method. Characterization studies such as X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy have revealed that the synthesized nanocomposites are homogenously distributed, having an average size of ~49 nm with a cubical spinel structure. The toxic 1-amino-nitrobenzene was initially treated with a sonophotochemical process in the presence of synthesized nanocomposites, resulting in lower efficiency, whereas with the addition of oxidants, the efficiency enhanced significantly. The parametric effects with respect to the initial solution pH, nanocomposites dose, 1-amino-nitrobenzene concentration, and oxidant concentration were studied, and it was found that an approximately 75% removal efficiency of 1-amino-nitrobenzene was achieved within 120 min. Further, the performance of the catalyst on the oxidation of 1-amino-nitrobenzene with sodium persulfate was also investigated, and it was found that a 95% removal efficiency was attained.

Ganoderic Acid (GA), a major bioactive compound isolated from the East Asian medicinal mushroom Ganoderma tsugae, is traditionally believed to have significant medicinal properties. GA is poorly soluble in water, which poses several challenges in terms of its formulation. In this study, Ganoderma tsugae extracts obtained through ethanol extraction were encapsulated in nanodispersions via ultrasonic cavitation and solvent evaporation to increase their bioavailability. The preparation route was thoroughly analyzed using Response Surface Methodology (RSM) to determine the interactions between the variables. Based on the results, the Hydrophilic–Lipophilic Balance (HLB) and the evaporation temperature significantly influenced the resulting particle size. In the optimized nanodispersions, GA was incorporated into a hydrophobic core with a particle size no greater than 200 nm and a very narrow particle distribution (namely, a polydispersity index of 0.289). Due to the high negative zeta potential (−45.9 mV), a very slow particle growth rate of 0.239% over short-term storage (14 days) was achieved. In addition, the zeta average remained virtually unchanged for 14 days at room temperature in solutions at different pH levels. In summary, this paper provides the first-ever demonstration that ultrasound cavitation in conjunction with solvent evaporation can be used to generate GA nanodispersions. [ABSTRACT FROM AUTHOR]

The complex structured starch particles were reduced to the nanoscale size range through hydrolysis utilizing low concentration acid assisted by ultrasound irradiation. The synthesized starch nanoparticles (SNPs) were characterized by transmission electron microscopy (TEM), Fourier‐transform infrared (FTIR), and X‐ray diffraction (XRD) techniques. The synthesized SNPs possessed surface activated entities, as many cationic functional groups were confirmed through the FTIR spectrum. Also, these SNPs were effectively utilized to separate heavy Cu metal ions from the synthetic ion solution. The SNPs were characterized using field emission scanning electron microscope (FESEM), X‐ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis for the surface modification after the adsorption process. The weak electrostatic interaction between the SNP surface and Cu ion was confirmed by the XPS spectrum and energy‐dispersive X‐ray spectroscopy. The maximum efficiency of Cu ions removal was about 93% at an optimal pH 5 and 25 mg/ml dosage. The adsorption equilibrium was obtained in 60 min. The nitrogen isotherm BET analysis of SNPs after adsorption shows a higher specific surface area of 18.552 m2/g, attributed to the interaction and presence of Cu ions on the SNP surface. The process feasibility was validated by the Langmuir isotherm model. The process exhibits pseudo‐second‐order adsorption kinetics and follows the Langmuir isotherm. The RL predicted by the Langmuir isotherm mechanism is 0.017, implying favourable adsorption. The process is reproducible and allows for the separation of heavy metal ions from the wastewater through biosorption effectively. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) composites were prepared by reinforcing with suitable hybrid fillers such as short sisal fibers treated with an alkali and high-intensity ultrasound (HIU) and halloysite nanotubes (HNTs) modified with 3-aminopropyltriethoxysilane. The synergistic effect of surface-treated short sisal fibers and silane-grafted HNTs were systematically evaluated through morphological, mechanical, dynamic mechanical, and thermal characterization. Alkali and HIU treatments of short sisal fibers drastically enhanced the interaction between sisal fibers and silane-grafted HNTs, which improved the interfacial adhesion between the filler system and the PP matrix. Scanning electron microscopic images indicated the continuity and smoothness of the hybrid composite surfaces. Dynamic mechanical analysis confirmed improved interactions between the hybrid filler system and the matrix, leading to significantly enhanced storage modulus in the hybrid composites. Therefore, the interfacial adhesion between the fillers and the matrix plays a significant role in improving the mechanical, dynamic mechanical, and thermal properties of polymer composites. [ABSTRACT FROM AUTHOR]

This study effectively demonstrates the sonochemical synthesis of visible-light-responsive Cu-ZnO/TiO2 ternary Z-scheme heterojunction nanocomposite photocatalyst. The as-prepared photocatalyst was comprehensively characterized by techniques including high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDX) and elemental dot mapping, X-ray diffraction (XRD), UV-Vis-diffuse reflectance spectroscopy (UV-Vis-DRS), Brunauer–Emmett–Teller (BET) surface area, and Fourier-transform infrared spectroscopy (FTIR). The photocatalytic activity of the Cu-ZnO/TiO2 nanocomposite photocatalyst was assessed for the degradation of Congo red (CR), an azo dye, under direct sunlight. The pseudo-first-order rate constant for CR degradation was found to be 0.09 min−1. The outcome implies that the synthesised nanocomposite photocatalyst demonstrates excellent photocatalytic activity under direct sunlight as 98% degradation of CR dye was achieved in approximately 20 min using the Cu-ZnO/TiO2 nanocomposite photocatalyst. Furthermore, its high recoverability and reusability of five times indicate its excellent catalytic potential. [ABSTRACT FROM AUTHOR]

Mushrooms possess therapeutic attributes such as anti-cancer, immunomodulation, antioxidant, hypolipidaemic, antiviral, antibacterial, hepatoprotection, and antidiabetic effects. In the family Pleurotaceae , Pleurotus spp. is the second most important commercial mushroom. The most widely cultivated Pleurotus spp. is Pleurotus ostreatus , followed by Pleurotus pulmonarius. Several bioactive compounds of Pleurotus spp., such as carbohydrates, glycoproteins, lipids, or secondary metabolites, could be attributed to its health properties. However, in most studies focusing on the therapeutic effects of Pleurotus spp., traditional extraction methods were used to obtain its extracts. Most conventional extraction methods, such as maceration, hot water extraction, and Soxhlet extraction, can be time-consuming and require a larger volume of solvents. Alternative extraction methods often have shorter extraction times, decreased solvent volume, and sometimes allow for the extraction of thermolabile constituents. This review discusses the bioactive compounds of Pleurotus mushrooms, highlights important considerations for extraction processes, explores both conventional and alternative extraction techniques to obtain bioactive compounds from Pleurotus spp., discusses their advantages and limitations, as well as evaluates their impact on extract bioactivities and therapeutic properties. [Display omitted] • Pleurotus spp. are among the most widely cultivated and consumed mushrooms. • Bioactive compounds in Pleurotus are mostly extracted by conventional methods. • Alternative methods using reduced extraction time, temperature and solvent is key. • These efficient and eco-friendly methods can target selected compounds. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Degradation of BDE-209 by combined Sono-Fenton treatment is effective. • The effect of operational parameters on the degradation of BDE-209 was investigated. • HPLC and GC–MS analyses demonstrated the presence of degraded products. • A complete degradation of BDE-209 was achieved within 80 min of treatment. Abstract Polybrominated diphenyl ethers, used as flame retardants are a cause of concern over past several years, due to their toxicity, bioaccumulation and widespread distribution. In this work, the combination of ultrasound and advanced Fenton process was investigated for the degradation of Decabromodiphenyl ether (BDE-209). The effect of pollutant concentration, solution pH, ultrasonic power density and loading of Fenton's reagent on the extent of BDE-209 degradation were studied. The results indicated an enhancement in the degradation of BDE-209 during Sono-Fenton treatment, leading to a complete degradation within 80 min of treatment, whereas only 40% and 25% degradation were achieved during ultrasound and Fenton treatment alone. To understand the degradation mechanism, analytical techniques including High performance liquid chromatography and Gas chromatography mass spectroscopy were employed to monitor the concentrations of parent compound along with degradation products. The degradation mechanism was proposed based on the identified degradation products. Total organic carbon (TOC) analysis demonstrated 60% TOC removal within 80 min of treatment. The obtained results suggest that the initiation of BDE-209 degradation during Sono-Fenton treatment followed thermal decomposition at bubble-vapor interface along with reductive debromination at iron surface, accompanied by oxidative degradation of lower brominated congeners at liquid bulk. This work illustrated an effective method for the removal of BDE-209 and hence providing an efficient wastewater treatment solution for recalcitrant pollutants. [ABSTRACT FROM AUTHOR]

In this study, a simple sugaring-out supported by liquid biphasic flotation technique combined with ultrasonication was introduced for the extraction of proteins from microalgae. Sugaring-out as a phase separation method is novel and has been used in the extraction of metal ions, biomolecules and drugs. But, its functioning in protein separation from microalgae is still unknown. In this work, the feasibility of sugaring-out coupled with ultrasound for the extraction of protein was investigated. Primary studies were carried out to examine the effect of sonication on the microalgae cell as well as the separation efficiency of the integrated method. Effect of various operating parameters such as the concentration of microalgae biomass, the location of sonication probe, sonication time, ultrasonic pulse mode (includes varying ON and OFF duration of sonication), concentration of glucose, types of sugar, concentration of acetonitrile and the flow rate in the flotation system for achieving a higher separation efficiency and yield of protein were assessed. Besides, a large-scale study of the integration method was conducted to verify the consistency of the followed technique. A maximum efficiency (86.38%) and yield (93.33%) were attained at the following optimized conditions: 0.6% biomass concentration, 200 g/L of glucose concentration, 100% acetonitrile concentration with 5 min of 5 s ON/10 s OFF pulse mode and at a flow rate of 100 cc/min. The results obtained for large scale were 85.25% and 92.24% for efficiency and yield respectively. The proposed liquid biphasic flotation assisted with ultrasound for protein separation employing sugaring-out demonstrates a high production and separation efficiency and is a cost-effective solution. More importantly, this method provides the possibility of extending its application for the extraction of other important biomolecules. [ABSTRACT FROM AUTHOR]

Sonochemistry, an almost a century old technique was predominantly employed in the cleaning and extraction processes but this tool has now slowly gained tremendous attention in the synthesis of nanoparticles (NPs) where particles of sub-micron have been produced with great stability. Following this, ultrasonication techniques have been largely employed in graphene synthesis and its dispersion in various solvents which would conventionally take days and offers poor yield. Ultrasonic irradiation allows the production of thin-layered graphene oxide (GO) and reduced graphene oxide (RGO) of up to 1 nm thickness and can be produced in single layers. With ultrasonic treatment, reactions were made easy whereby graphite can be directly exfoliated to graphene layers. Oxidation to GO can also be carried out within minutes and reduction to RGO is possible without the use of any reducing agents. In addition, various geometry of graphene can be produced such as scrolled graphene, sponge or foam graphene, smooth as well as those with rough edges, each serving its own unique purpose in various applications such as supercapacitor, catalysis, biomedical, etc. In ultrasonic-assisted reaction, deposition of metal NPs on graphene was more homogeneous with custom-made patterns such as core-shell formation, discs, clusters and specific deposition at the edges of graphene sheets. Graphene derivatives with the aid of ultrasonication are the perfect catalyst for various organic reactions as well as an excellent adsorbent. Reactions which used to take hours and days were significantly reduced to minutes with exceedingly high yields. In a more recent approach, sonophotocatalysis was employed for the combined effect of sonication and photocatalysis of metal deposited graphene. The system was highly efficient in organic dye adsorption. This review provides detailed fundamental concepts of ultrasonochemistry for the synthesis of graphene, its dispersion, exfoliation as well as its functionalization, with great emphasis only based on recent publications. Necessary parameters of sonication such as frequency, power input, sonication time, type of sonication as well as temperature and dual-frequency sonication are discussed in great length to provide an overview of the resultant graphene products. [ABSTRACT FROM AUTHOR]

Sonophotocatalysis (SPC) is considered to be one of the important wastewater treatment techniques and hence attracted the attention of researchers to eliminate recalcitrant hazardous organic pollutants from aqueous phase. In general, SPC refers to the integrated use of ultrasonic sound waves, ultraviolet radiation and the addition of a semiconductor material which functions as a photocatalyst. Current research has brought numerous improvements in the SPC based treatment by opting visible light irradiation, nanocomposite catalysts and numerous catalyst supports for better stability and performance. This review accomplishes a critical analysis with respect to the recent advancements. The efficiency of SPC based treatments has been analyzed by considering the individual methods i.e. sonolysis, photocatalysis, sonophotolysis, sono-ozone, photo-Fenton and sono-Fenton. Besides, the essential parameters such as solution temperature, concentrations of initial pollutant and catalyst, initial pH, dosages of Fenton’s reagent and hydrogen peroxide (H 2 O 2 ), ultrasonic power density, gas sparging, addition of radical scavenger, addition of carbon tetrachloride and methanol have been discussed with suggestions for the selection of optimum parameters. A higher synergistic pollutant removal rate has been reported during SPC treatment as compared to individual methods and the implementation of numerous doping materials and supports for the photocatalyst enhances the degradation rate of pollutants using DSPC under both visible and UV irradiation. Overall, SPC and DSPC based wastewater treatments are emerging as potential techniques as they provide effective solution in removing the recalcitrant organic pollutants and progressive research is expected to bring out superior treatment efficiency using these advanced technologies. Importance of this review The review has accomplished a thorough and a critical analysis of sonophotocatalysis (SPC) based on the recently published journals. Recent advancements in the doped sonophotocatalysis (DSPC) and the mechanisms behind synergistic enhancement in the pollutant degradation rate have been discussed with justifications. Besides, the possible future works are suggested for the advancements in sonophotocatalysis based treatment. This review will be beneficial for electing a SPC based method because of the accomplished sharp comparisons among the published results. The review includes current advancements of SPC based methods which aid for a low-cost and a large-scale wastewater treatment application. [ABSTRACT FROM AUTHOR]

Curcumin has been found to possess significant pharmaceutical activities. However, owing to its low bioavailability, there is a limitation of employing it towards clinical application. In an attempt to surmount this implication, often the choice is designing novel drug delivery systems. Herein, sterically stabilized nanoscale dispersion loaded with curcumin (nanodispersion) based on non-ionic colloidal system has been proposed. In this study, the process conditions were effectively optimized using response surface methodology (RSM) with Box-Behnken design (BBD). The suggested optimum formulation proved to be an excellent fit to the actual experimental output. STEM images illustrate that the optimal curcumin-loaded nanodispersion has spherical morphology with narrow particle size distribution. Particle size distribution study confirms that the solution pH does not affect the nanodispersion, and physical stability study shows that the colloidal system is stable over 90 days of storage at ambient conditions. More importantly, controlled release profile was achieved over 72 h and the in vitro drug release data fit well to Higuchi model ( R2=0.9654). [ABSTRACT FROM AUTHOR]

Curcumin has been found to possess significant pharmaceutical activities. However, owing to its low bioavailability, there is a limitation of employing it towards clinical application. In an attempt to surmount this implication, often the choice is designing novel drug delivery systems. Herein, sterically stabilized nanoscale dispersion loaded with curcumin (nanodispersion) based on non-ionic colloidal system has been proposed. In this study, the process conditions were effectively optimized using response surface methodology (RSM) with Box-Behnken design (BBD). The suggested optimum formulation proved to be an excellent fit to the actual experimental output. STEM images illustrate that the optimal curcumin-loaded nanodispersion has spherical morphology with narrow particle size distribution. Particle size distribution study confirms that the solution pH does not affect the nanodispersion, and physical stability study shows that the colloidal system is stable over 90 days of storage at ambient conditions. More importantly, controlled release profile was achieved over 72 h and the in vitro drug release data fit well to Higuchi model (R² = 0.9654). [ABSTRACT FROM AUTHOR]

The ultrasonic-assisted extraction of polysaccharides (PS) from Ganoderma lucidum, was subjected to a scale-up study. 0.25 L extractor was used to optimize the extraction conditions toward maximum yield of PS. The extracted PS was observed to be reduced by increasing the scale from 1 to 6 L. To intensify the extraction, axial circulation at different stirring rates was induced and optimized in a 3 L U-tube extractor. Although circulation at 300 rpm improved the yield of PS for 3 L, introducing dispersion geometry (conical funnel) and adjusting the radiation distance in a 6 L U-tube extractor further intensified the extraction efficiency. A radiation distance of 4 cm and circulation induced using 600 rpm enhanced the PS as compared to the conventional 6 L extractor. Overall, the scale-up from 0.25 to 6 L was successful and introducing circulation and dispersion geometry intensified the extraction efficiency under similar dissipation of ultrasonic power. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1483-1491, 2015 [ABSTRACT FROM AUTHOR]

Highlights: [•] Ultrasound cavitation induced POME treatment. [•] Triple frequency ultrasound cavitation reactor was used to check the frequency effects. [•] Role of H2O2 in avoiding the fluctuating pattern of COD has been noted. [•] Promising and a fruitful green process engineering technique for POME treatment. [Copyright &y& Elsevier]

Abstract: In the present study, response surface methodology (RSM) based on central composite design (CCD) was employed to investigate the influence of main emulsion composition variables, namely drug loading, oil content, emulsifier content as well as the effect of the ultrasonic operating parameters such as pre-mixing time, ultrasonic amplitude, and irradiation time on the properties of aspirin-loaded nanoemulsions. The two main emulsion properties studied as response variables were: mean droplet size and polydispersity index. The ultimate goal of the present work was to determine the optimum level of the six independent variables in which an optimal aspirin nanoemulsion with desirable properties could be produced. The response surface analysis results clearly showed that the variability of two responses could be depicted as a linear function of the content of main emulsion compositions and ultrasonic processing variables. In the present investigation, it is evidently shown that ultrasound cavitation is a powerful yet promising approach in the controlled production of aspirin nanoemulsions with smaller average droplet size in a range of 200–300nm and with a polydispersity index (PDI) of about 0.30. This study proved that the use of low frequency ultrasound is of considerable importance in the controlled production of pharmaceutical nanoemulsions in the drug delivery system. [Copyright &y& Elsevier]

Catalysts increase reaction rates; however, the surface area to volume ratio of catalysts has a vital role in catalytic activity. The noble metals such as platinum (Pt) and gold (Au) are expensive; despite this, they have proven their existence in catalysis, motivating the synthesis of supported metal catalysts. Metal catalysts need to be highly dispersed onto the support. In this investigation, an ultrasound approach has been attempted to synthesise highly photoactive titanium dioxide (TiO2) nanoparticles by the hydrolysis of titanium tetraisopropoxide in an acetone/methanol mixture. To enhance its photocatalytic activity, TiO2 was doped with Pt. The synthesised photocatalyst was characterised by techniques such as particle size analysis (PSA), XRD, FE-SEM, TEM, and EDX. The enhancement in the surface characteristics of Pt-doped TiO2 compared with bare TiO2 support was confirmed with Brunauer–Emmett–Teller (BET) analysis. The enhanced surface area and uniformity in particle size distribution at the nanoscale level were due to the effects of ultrasonic irradiation. The obtained results corroborated the size and composition of the synthesised catalysts. The size of the catalysts is in the nanometre range, and good dispersion of Pt catalysts over the TiO2 support was observed. The UV-Visible spectroscopy analysis was performed to study the optical properties of the synthesised TiO2 and Pt/TiO2 photocatalysts. An increase in the absorbance was noted when Pt was added to TiO2, which is due to the decrease in the band gap energy. [ABSTRACT FROM AUTHOR]

In this study, a novel nanocomposite of bimetallic Ag–Co nanoparticles supported on cellulose nanofibers (CNFs) was synthesised using the ultrasound-assisted wet-impregnation method for catalytic applications. CNFs were prepared from cellulose acetate using the electrospinning technique. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the successful synthesis of CNFs. Further, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) revealed a uniform dispersion of Ag and Co metals on the CNFs. At the same time, X-Ray diffraction (XRD) spectra indicated the highly crystalline nature of the as-produced composite. The hydrogenation of 4-nitrophenol (4-NP) was used to study the efficiency of the synthesised nanocomposite. The progress of the reaction was examined via UV–visible spectroscopy. It was noted that Ag-Co nanoparticles supported on CNFs catalysed the hydrogenation of 4-NP (0.1 mM) to 4-aminophenol within just 110 s with an apparent rate constant of 0.0172 s−1. This study proved that the obtained catalysts have superior stability and reusability with about 100% conversion up to 5 cycles. The excellent activity of the as-synthesised Ag-Co/CNFs nanocomposites makes it a promising nanocatalyst for catalytic applications. [Display omitted] • An ecological, cellulose based Ag–Co/CNF nanocomposite catalyst was developed. • Uniform distribution of spherical Ag and Co nanoparticles (15 nm) over CNF were obtained. • Catalytic potential of the as-prepared catalyst was tested for the 4-NP hydrogenation. • Complete conversion of 4-NP with k app = 0.0172 s−1 within 110 s was obtained. • The nanocomposite offers better stability and efficiency even up to five cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • An effective ultrasound-assisted mechano-chemical cracking method has been proposed. • NMP is found to be a more effective polar solvent than water. • Ultrasonication promotes and propagates the self-repulsion of biochar layers. • 8–10% monolayer, up to 96% less than four layers GO produced from miscanthus. • Small amounts of graphene quantum dots were also observed during GO synthesis. Whilst graphene materials have become increasingly popular in recent years, the followed synthesis strategies face sustainability, environmental and quality challenges. This study proposes an effective, sustainable and scalable ultrasound-assisted mechano-chemical cracking method to produce graphene oxide (GO). A typical energy crop, miscanthus, was used as a carbon precursor and pyrolysed at 1200 °C before subjecting to edge-carboxylation via ball-milling in a CO 2 -induced environment. The resultant functionalised biochar was ultrasonically exfoliated in N -Methyl-2-pyrrolidone (NMP) and water to form GOs. The intermediate and end-products were characterised via X-ray diffraction (XRD), Raman, high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM) analyses. Results show that the proposed synthesis route can produce good quality and uniform GOs (8–10% monolayer), with up to 96% of GOs having three layers or lesser when NMP is used. Ultrasonication proved to be effective in propagating the self-repulsion of negatively-charged functional groups. Moreover, small amounts of graphene quantum dots were observed, illustrating the potential of producing various graphene materials via a single-step method. Whilst this study has only investigated utilising miscanthus, the current findings are promising and could expand the potential of producing good quality graphene materials from renewable sources via green synthesis routes. [ABSTRACT FROM AUTHOR]

Ultrasound and Microchannel coupling for the generation of nanoemulsions. • Nanoemulsion was generated by coupling ultrasound and microchannel. • The implemented process intensification strategy led to creating a smaller monodispersed nanoemulsion system. • Microchannels of multiple dimensions were used to realize their impact. • Further controlling parameters were tested, accompanying with the stability of nanoemulsion. O/W nanoemulsions are isotropic colloidal systems constituted of oil droplets dispersed in continuous aqueous media and stabilised by surfactant molecules. Nanoemulsions hold applications in more widespread technological domains, more crucially in the pharmaceutical industry. Innovative nanoemulsion-based drug delivery system has been suggested as a powerful alternative strategy through the useful means of encapsulating, protecting, and delivering the poorly water-soluble bioactive components. Consequently, there is a need to generate an emulsion with small and consistent droplets. Diverse studies acknowledged that ultrasonic cavitation is a feasible and energy-efficient method in making pharmaceutical-grade nanoemulsions. This method offers more notable improvements in terms of stability with a lower Ostwald ripening rate. Meanwhile, a microstructured reactor, for instance, microchannel, has further been realised as an innovative technology that facilitates combinatorial approaches with the acceleration of reaction, analysis, and measurement. The recent breakthrough that has been achieved is the controlled generation of fine and monodispersed multiple emulsions through microstructured reactors. The small inner dimensions of microchannel display properties such as short diffusion paths and high specific interfacial areas, which increase the mass and heat transfer rates. Hence, the combination of ultrasonic cavitation with microstructures (microchannel) provides process intensification of creating a smaller monodispersed nanoemulsion system. This investigation is vital as it will then facilitate the creation of new nanoemulsion based drug delivery system continuously. Following this, the fabrication of microchannel and setup of its combination with ultrasound was conducted in the generation of O/W nanoemulsion, as well as optimisation to analyse the effect of varied operating parameters on the mean droplet diameter and dispersity of the nanoemulsion generated, besides monitoring the stability of the nanoemulsion. Scanning transmission electron microscopy (STEM) images were also carried out for the droplet size measurements. In short, the outcomes of this study are encouraging, which necessitates further investigations to be carried out to advance a better understanding of coupling microchannel with ultrasound to produce pharmaceutical-grade nanoemulsions. [ABSTRACT FROM AUTHOR]

Highlights • A stable palm oil-based water-in-oil nano-emulsion was formulated using ultrasound. • Lipid peroxidation did not occur for the processed water-in-oil nano-emulsion. • Ultrasound is found to be more energy-efficient than microfluidizer for producing nano-emulsion. • Viscosity of water-in-oil nano-emulsion influences sedimentation and droplets size. • NaCl improves nano-emulsion stability through electrostatic and steric repulsions. Abstract This study aimed to formulate a stable palm oil-based water-in-oil (W/O) nano-emulsion. Emphasis was placed on the effects of polyglycerol polyricinoleate (PGPR), medium chain triglyceride (MCT), lecithin and sodium chloride (NaCl) addition towards the stability of nano-emulsion. Among the performed analyses were mean droplet diameter (MDD), dispersity index (DI), critical micelle concentration (CMC), lipid peroxidation, viscosity, sedimentation index (SI) and surface morphology. The most stable optimized palm oil-based W/O nano-emulsion was produced using 61.25 wt% of palm oil, 26.25 wt% of MCT, 2.5 wt% of PGPR and 10 wt% of water (0.5 M of NaCl). The MDD and DI of the obtained W/O nano-emulsion were 143.1 ± 8.8 and 0.131 ± 0.094, respectively. After 2 weeks, no sedimentation was observed in W/O nano-emulsion with MDD and DI were 151.2 ± 6.5 nm and 0.156 ± 0.025 respectively. This study clearly found that polyricinoleate non-polar fatty acids of PGPR bound to non-polar fatty acids of palm oil through van der Waals intermolecular forces. While, polyglycerol polar head of PGPR interacts with water molecules through hydrogen bonding, as well as by the bound glyceride units of palm oil. The addition of NaCl further reduced MDD by 70 nm and improved the stability of nano-emulsion through electrostatic and steric repulsions attributed to the dissociation of Na+ and Cl− ions. This study aids to widen the knowledge and interest on the utilization of palm oil for the generation of W/O nano-emulsion, as well as to better understand the interaction between palm oil and PGPR/NaCl in producing nano-emulsion. [ABSTRACT FROM AUTHOR]

Highlights • Prospects of ultrasound in hydroxylating graphene. • Prospects of ultrasound in hydroxylating Buckminsterfullerene. • Design aspects for large-scale sonochemical hydroxylation. • Statistical approach to optimize sonochemical variables. Abstract The main objective of this review is to derive the salient features of previously developed ultrasound-assisted methods for hydroxylating graphene and Buckminsterfullerene (C 60). The pros and cons associated to ultrasound-assisted synthesis of hydroxy-carbon nanomaterials in designing the strategical methods for the industrial bulk production are also discussed. A guideline on the statistical methods has also been considered to further provide the scopes towards the application of the previously reported methods. Irrespective of many useful methods that have been developed in order to functionalize C 60 and graphene by diverse oxygenated functional groups e.g. epoxide, hydroxyl, carboxyl as well as metal/metal oxide via a combination of organic chemistry and sonochemistry, there is no report dealing exclusively on the application of ultrasonic cavitation particularly to synthesising polyhydroxylated carbon nanomaterials. On this context, this review emphasizes in investigating the critical aspects of sono-nanochemistry and the statistical approaches to optimize the variables in the sonochemical process towards a large-scale synthesis of polyhydroxylated graphene and C 60. [ABSTRACT FROM AUTHOR]

In this investigation, sisal fibres were treated with the combination of alkali and high intensity ultrasound (HIU) and their effects on the morphology, thermal properties of fibres and mechanical properties of their reinforced PP composites were studied. FTIR and FE-SEM results confirmed the removal of amorphous materials such as hemicellulose, lignin and other waxy materials after the combined treatments of alkali and ultrasound. X-ray diffraction analysis revealed an increase in the crystallinity of sisal fibres with an increase in the concentration of alkali. Thermogravimetric results revealed that the thermal stability of sisal fibres obtained with the combination of both alkali and ultrasound treatment was increased by 38.5 °C as compared to the untreated fibres. Morphology of sisal fibre reinforced composites showed good interfacial interaction between fibres and matrix after the combined treatment. Tensile properties were increased for the combined treated sisal fibres reinforced PP composites as compared to the untreated and pure PP. Tensile modulus and strength increased by more than 50% and 10% respectively as compared to the untreated sisal fibre reinforced composite. It has been found that the combined treatment of alkali and ultrasound is effective and useful to remove the amorphous materials and hence to improve the mechanical and thermal properties. [ABSTRACT FROM AUTHOR]

The physicochemical properties of blackberry cell walls under air drying with and without contact ultrasonication were analysed, and their ability to bind soluble phenolics was evaluated. Compared to air drying alone, ultrasound promoted cell wall shrinkage and reduced their specific surface area and water binding capacity. Meanwhile, the in-process ultrasound further increased the amount of water soluble pectin (WSP) and decreased protopectin. After drying, the cell walls of ultrasound-dried samples contained 11.6% less protopectin (PP) than air-dried samples. Pectins in ultrasound-dried samples were also more aggregated with a reduced branching degree of Rhamnogalacturonan-I (RG-I). Most of these ultrasonic modifications of blackberry cell walls hindered their phenolics acquirement. The equilibrium adsorption capacities of cell walls from ultrasound-dried blackberries for 1 h were 33.5% (for catechin) and 21.8% (for phloretic acid) lower than the counterparts from air-dried samples for 8 h. Although the soluble phenolics absorbed by dried blackberry cell walls were more thermal-stable than those adsorbed by fresh blackberry cell walls, the overall protection provided by cell walls was still regarded as attenuated with drying due to the decline in the adsorption ability. Besides, it is believed that the higher retention of soluble phenolics in ultrasound dried samples is ascribed to the shortened thermal-drying time rather than the cell walls-phenolics interactions. These findings provide an in-depth understanding of the effect of ultrasound drying on phenolic stability. [Display omitted] • Ultrasound reduced specific surface area and water binding capacity of cell walls. • Ultrasound increased the amount of water soluble pectin and decreased protopectin. • The ultrasound-intensified drying decreased the branching degree of RG-I pectin. • The ability of cell walls to absorb soluble phenolics was reduced after sonication. • The protections on soluble phenolics provided by cell walls weakened with drying. [ABSTRACT FROM AUTHOR]

The molecular diffusion of phenolics inside walnut pellicle fiber particles under solid-liquid extraction enhanced by ultrasound (US), orbital agitation (OA), impeller agitation (IA), and the combined microwave and impeller agitation (MW-IA) were explored. Numerical modeling considering the temperature-dependent diffusivity revealed that the internal diffusivity of phenolics was the highest under MW-IA and the lowest under OA. At 35 °C, IA (126.246 mg/g, t = 10 min) was more effective to strengthen the phenolic diffusivity than the US-39W (95.538 mg/g, t = 10 min). Due to the simultaneous enhancement of internal diffusivity and external dissolution, the MW-IA extraction reached equilibrium within 16 min, reaching the highest yield among all the treatments (176.944 mg/g). The extraction was then divided into the increasing and falling driving force periods. The comparison of phenolic diffusivity among MW-IA and IA roughly indicated that the proportion of non-thermal effect of microwave at 315 W was 889% higher than 189 W at the extraction equilibrium. Moreover, some soluble polyphenols, i.e. quercitrin and syringic acid, could be adsorbed by the cell wall after equilibrium. The correlations between any two soluble phenolics varied with the phenolic type, deducing that soluble phenolics may interact with each other either positively or negatively. Besides, the mining of phenolic data also indicated that intensive impeller agitation is a good substitution for ultrasonication to extract phenolics effectively. [Display omitted] • Solid-liquid extraction was modeled by a diffusion model with a temperature factor. • Diffusion was divided into the increasing and falling driving force periods. • Non-thermal effect of microwave at 315 W was 889% higher than 189 W at equilibrium. • Impeller agitation at a high temperature can be a substitute for ultrasound extraction. • Soluble polyphenols interact with each other either positively or negatively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Near zero lignin content nanocellulose was extracted via in situ ultrasound-assisted one-pot treatment. • The optimal setup for the in situ ultrasound-assisted one-pot system involves a 7.5-minute ultrasound interval with 900 W ultrasound irradiation. • Nanocellulose with web-like structure was produced by varying ultrasound irradiation time. Nanocellulose (CNF) has emerged as a promising alternative to synthetic petroleum-based polymers, but the conventional preparation process involves multiple tedious steps, heavily dependent on chemical input, and proves cost-inefficient. This study presented an, in situ ultrasound-assisted extraction using deep eutectic solvent (DES) based on choline chloride and oxalic acid for more facile production of CNF from raw durian husk fibers. FESEM analysis confirmed the successful extraction of web-like nanofibril structure with width size ranging from 18 to 26 nm. Chemical composition analysis and FTIR revealed the selective removal of lignin and hemicellulose from the raw fiber. As compared to post-ultrasound treatment, in situ ultrasound-assisted extraction consistently outperforms, yielding a higher CNF yield with finer fiber width and significantly reduced lignin content. Integrating this eco-friendly in situ ultrasonication-assisted one-pot extraction method with a 7.5 min interval yielded the highest CNF yield of 58.22 % with minimal lignin content. The superior delignification ability achieved through the proposed in situ ultrasound-assisted protocol surpasses the individual efficacy of DES and ultrasonication processes, neither of which yielded CNF in our experimental setup. This single-step fabrication process significantly reduces chemical usage and streamlines the production steps yielding web-structured CNF that is ideal for sustainable application in membrane and separator. [ABSTRACT FROM AUTHOR]

• A stable palm oil-based W/O/W multiple nanoemulsion was formulated. • Ultrasound is found to be more energy-efficient than microfluidizer to produce W/O/W. • Co-interaction of PGPR, palm oil, and sucragel imparted stability at the interphase. • Oil thickener provided better stability than water thickeners. • Isotonicity enhanced the stability of W/O/W. In this work, the effects of thickeners and tonicity towards producing stable palm oil-based water-in-oil-in-water (W/O/W) multiple nanoemulsion using ultrasound and microfluidizer were investigated. Palm oil, Sucragel, polyglycerol polyricinoleate, Tween 80, Xanthan gum, and NaCl were used. W/O/W was formed under the optimized conditions of ultrasound at 40% amplitude and for 180 s of irradiation time, whereas for the microfluidizer, the optimized conditions were 350 bar and 8 cycles. This is the first work that successfully utilized Sucragel (oil-based thickener) in imparting enhanced stability in W/O/W. W/O/W with isotonic stabilization produced the lowest change in the mean droplet diameter (MDD), NaCl concentration, and water content by 1.5%, 2.6%, and 0.4%, respectively, due to reduced water movement. The final optimized W/O/W possessed MDD and dispersity index of 175.5 ± 9.8 and 0.232 ± 0.012, respectively. The future direction of formulating stable W/O/W would be by employing oil phase thickeners and isotonicity. The observed ~12 times lesser energy consumed by ultrasound than microfluidizer to generate a comparable droplet size of ~235 nm, further confirms its potential in generating the droplets energy-efficiently. [ABSTRACT FROM AUTHOR]

Kinetics and Mechanism of Low Frequency Ultrasound driven Elimination of Trace Level Aqueous Perfluorooctanesulfonic acid and Perfluorooctanoic acid. • Low-frequency sonication is effective for the removal of PFOX. • Thermal decomposition at the interfacial region indicated to be the predominant degradation pathway. • Higher ultrasonic power has a greater impact on PFOX degradation. • Up-to seven degraded products of PFOX were identified during sonolysis. Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the most investigated persistent organic pollutants due to their adverse health concerns and inertness in elimination. The wastewater treatment of PFOX (PFOS and PFOA) has been investigated by sonochemical method while implementing a 20-kHz probe-type sonicator with ultrasound power variance from 150 to 375 W. Highest degradation rate was achieved under optimum parameters such as PFOX initial concentration, ultrasound power level, solution pH and temperature. Complete removal of PFOX was obtained within 80 min of sonochemical treatment as exhibited by liquid chromatography–mass spectroscopy analysis. Change in the bulk phase temperature from the optimum value of 20 °C and the decline in ultrasound power demonstrated a detrimental effect on the degradation rate. The degradation rate enhanced with an increase in PFOX initial concentration from 20 to 220 pM, beyond which the rate declined. The reaction kinetics were observed to follow pseudo first order-up-to 400 pM and zero order kinetics beyond 400 pM of initial concentration. Following the degradation mechanism, PFOX is assumed to undergo thermal decomposition at bubble interfacial region along with pyrolysis of intermediates inside the cavity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Extraction of yellow dye from Cassia alata flower petals, and optimization. • Ultrasonic bath, probe, and conventional heating used for yellow dye extraction. • Characterization of the yellow dye, as well as dyeing (cotton, silk, and leather) without mordant. • Yellow dye was further evaluated to determine its antibacterial activity against skin bacteria. Using natural dyes in dyeing industries becomes an alternative to synthetic dyes, which are known to contain harmful chemicals that can pose risks to the environment and human health. This study involves the extraction of yellow dye from Cassia alata flower petals, optimization of the extraction process using an ultrasonic bath (40 KHz and an input power of 500), ultrasonic probe (390 W, 455 W, 520 W, 585 W, and 650 W), and conventional heating (heating mantle with 30 °C, 40 °C, 50 °C, 60 °C, and 70 °C), characterization of the dye, as well as dyeing (cotton, silk, and leather) without using a mordant. The extracted yellow dye was further evaluated to determine its antibacterial activity against skin bacteria. Dye extraction optimization using UV–Visible spectrophotometric analysis revealed that the maximum yellow color in methanol extract (287 and 479 nm) was obtained at 50 °C for 45 min using ultrasonic water bath extraction, followed by the ultrasonic probe and direct heating. Based on the FTIR spectra, it is evident that O H is present at approximately 3300 cm−1, while C H stretches at around 2900 cm−1. A characteristic peak at 1608 cm−1 bears a striking similarity to anthraquinonoid-based compounds. Also, using the ultrasonic water bath dyeing technique at 50 °C for 45 min, the yellow color of cotton, silk, and leather was dyed optimally. Due to effective color removal after two washings with boiling soap liquid, the dyed cotton and silk fabric displayed good washing and rubbing fastness. Regarding antibacterial activity, the dye was highly active against all pathogens after extraction in methanol. The maximum inhibition was observed against Pseudomonas sp. with a MIC value of 1.56 mg/ml. [ABSTRACT FROM AUTHOR]

Graphene is one of the highly explored nanomaterials due to its unique and extraordinary properties. In this study, by utilizing a hydrothermal reduction method, graphene oxide (GO) was successfully converted to reduced graphene oxide (RGO) without using any toxic reducing agents. Following this, with the use of ultrasonic cavitation, profoundly stable few layer thick RGO nanodispersion was generated without employing any stabilizers or surfactants. During ultrasonication, shockwaves from the collapse of bubbles cause a higher dispersing energy to the graphene nanosheets which surpass the forces of Van der Waal’s and π-π stacking and thus pave the way to form a stable aqueous nanodispersion of graphene. Ultrasonication systems with different power intensity have been employed to determine the optimum conditions for obtaining the most stable RGO dispersion. The optimised conditions of ultrasonic treatments led to the development of a very stable reduced graphene oxide (RGO) aqueous dispersion. The stability was observed for two years and was analyzed by using Zetasizer by measuring the particle size and zeta potential at regular intervals and found to have exceptional stability. The excellent stability at physiological pH promotes its utilization in nano drug delivery application as a carrier for Paclitaxel (Ptx), an anticancer drug. The in vitro cytotoxicity analysis of Ptx loaded RGO nanodispersion by MTT assay performed on the cell lines revealed the potential of the nanodispersion as a suitable drug carrier. Studies on normal lung cells, MRC-5 and nasopharyngeal cancer cells, HK-1 supported the biocompatibility of RGO-Ptx towards normal cell line. This investigation shows the potential of exceptionally stable RGO-Ptx nanodispersion in nano drug delivery applications. [ABSTRACT FROM AUTHOR]

Ganoderma mushroom cultivated recently in Malaysia to produce chemically different nutritional fibers has attracted the attention of the local market. The extraction methods, molecular weight and degree of branching of (1-3; 1-6)-β- d -glucan polysaccharides is of prime importance to determine its antioxidant bioactivity. Therefore three extraction methods i.e. hot water extraction (HWE), soxhlet extraction (SE) and ultrasound assisted extraction (US) were employed to study the total content of (1-3; 1-6)-β- d -glucans, degree of branching, structural characteristics, monosaccharides composition, as well as the total yield of polysaccharides that could be obtained from the artificially cultivated Ganoderma . The physical characteristics by HPAEC-PAD, HPGPC and FTIR, as well as the antioxidant in vitro assays of DPPH scavenging activity and ferric reducing power (FRAP) indicated that (1-3; 1-6)-β- d -glucans of Malaysian mushroom have better antioxidant activity, higher molecular weight and optimal degree of branching when extracted by US in comparison with conventional methods. [ABSTRACT FROM AUTHOR]

Coupling multiple frequencies in ultrasonic systems is one of the highly desired area of research for sonochemists, as it is known for producing synergistic effects on various ultrasonic reactions. In this study, the characteristics of a hexagonal-shaped triple frequency ultrasonic reactor with the combination frequencies of 28, 40 and 70 kHz were studied. The results showed that uniform temperature increment was achieved throughout the reactor at all frequency combinations. On the other hand, sonochemiluminescence emission and degradation rate of Rhodamine B varies throughout different areas of the reactor, indicating the presence of acoustic ‘hot spots’ at certain areas of the reactor. Also, coupling dual and triple frequencies showed a decrease in the hydroxyl radical ( OH) production, suggesting probable wave cancelling effect in the system. The results can therefore be served as a guide to optimize the usage of a triple frequency ultrasonic reactor for future applications. [ABSTRACT FROM AUTHOR]

• Sonochemistry as an advanced oxidation process. • Mechanism of remediation/disinfection of microbial hazards in polluted water. • Types and comparison of sonochemical reactors for remediation. • Energy and economic aspects. • Challenges and recommendations for future studies. Water is one of the major sources that spread human diseases through contamination with bacteria and other pathogenic microorganisms. This review focuses on microbial hazards as they are often present in water and wastewater and cause various human diseases. Among the currently used disinfection methods, sonochemical reactors (SCRs) that produce free radicals combined with advanced oxidation processes (AOPs) have received significant attention from the scientific community. Also, this review discussed various types of cavitation reactors, such as acoustic cavitation reactors (ACRs) utilizing ultrasonic energy (UE), which had been widely employed, involving AOPs for treating contaminated waters. Besides ACRs, hydrodynamic cavitation reactors (HCRs) also effectively destroy and deactivate microorganisms to varying degrees. Cavitation is the fundamental phenomenon responsible for initiating many sonochemical reactions in liquids. Bacterial degradation occurs mainly due to the thinning of microbial membranes, local warming, and the generation of free radicals due to cavitation. Over the years, although extensive investigations have focused on the antimicrobial effects of UE (ultrasonic energy), the primary mechanism underlying the cavitation effects in the disinfection process, inactivation of microbes, and chemical reactions involved are still poorly understood. Therefore, studies under different conditions often lead to inconsistent results. This review investigates and compares other mechanisms and performances from greener and environmentally friendly sonochemical techniques to the remediation of microbial hazards associated with water and wastewater. Finally, the energy aspects, challenges, and recommendations for future perspectives have been provided. [ABSTRACT FROM AUTHOR]

In this study, black chokeberries were dehydrated by sequential calcium pretreatment and ultrasonic/microwave drying. The investigation focused on exploring the mechanisms of water transport and metabolic pathways of polyphenols. A diffusional model was modified by considering the factors such as shrinkage, porosity and temperature-dependent water diffusivity to simulate the moisture transport. Accordingly, the Spatio-temporal evolutions of cytoplasm water, extracellular water and total water content in black chokeberry throughout drying were successfully revealed. On the other hand, the quality attributes involved in the metabolic pathways of polyphenols, i.e., free/bound phenolics, cell wall pectin, polyphenol oxidase (PPO) or peroxidase (POD), and viscoelastic properties under these drying treatments were intensively analysed. Through correlation analysis, it was found that CaCl 2 pretreatment strengthened the oxidation of free procyanidin B 2 by PPO. In contrast, both ultrasound and microwave drying weakened the negative influence of PPO on the stability of free rutin. Besides, temperature rise promoted the loss of free polyphenols and the degradation of cell wall pectin, weakening the attachment of bounded-caffeic acid on the cell wall. This investigation provides new physical and chemical understandings about fruit drying and reveals the potential benefits of hybrid drying technologies. • CaCl 2 immersion was combined with ultrasound/microwave drying to dry black chokeberry. • A mass transfer model with temperature rising, shrinkage and porosity was built. • Decline of free procyanidin B 2 was caused by both enzymatic and thermal degradations. • Ultrasound and microwave treatments alleviated enzymatic degradation of free rutin. • Transformation of cell wall ASP to WSP contributed to the loss of bound caffeic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • The suitability of high-intensity ultrasound for the inactivation of enzymes in amla juice was investigated. • Inactivation rates as high as 90.72% and 73.18% for PPO and POD respectively were observed. • Optimized process included energy density of 1610 W cm−2 pulsed at 5 s on and 5 s off for 7 min 30 s. • The goodness of fit for approximation of responses was adequate (R2 > 0.90) The enzymatic browning induced in amla juice due to the high activity of polyphenol oxidase (PPO) and peroxidase (POD) is one of the critical issues faced by the industry. The present study assessed the suitability of non-thermal, high-intensity ultrasound (US) on the inactivation of PPO and POD in fresh Indian Gooseberry juice. Ultrasonic waves, using a 6 mm titanium alloy probe were irradiated in the juice at a maximum power of 455 W and frequency of 20 kHz. The subsequent effects on biochemical attributes were studied using response surface methodology. Inactivation rates of 90.72 % and 73.18 %, respectively, for PPO and POD enzymes, were observed at the highest US intensity and exposure time. Numerical optimisation using the three-factor, three-level Box-Behnken design suggested that an optimum process at 70 % (energy density: 1610 Wcm−2) pulsed at 5 s on and 5 s off for 7 min 30 s resulted in PPO and POD inactivation of the order of 76.42 % and 64.57 % respectively. At these experimental conditions, the optimized levels of biochemical attributes i.e., ascorbic acid (738.50 mg/100 mL), total phenols (17.10 mg/mL), DPPH antioxidant activity (58.47 %), tannins (7.11 µg/mL), colour change (Δ E = 9.04) and flavonoids (6.14 mg/mL) were achieved. The overall statistical models were significant for all the responses except for reducing sugars. Furthermore, the approximation equations for individual responses indicated that the goodness of fit was adequate (R 2 > 0.90). The results suggested that ultrasound is a suitable processing technique for amla juice stabilisation compared to thermal treatments that result in the loss of quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acoustic wave induces microstreaming, bubble oscillation, microjetting, and shockwave. • Ultrasound assists in improving nanocellulose properties and production efficiency. • Effects of ultrasonic parameters on nanocellulose extraction and surface modification. • Barriers to ultrasound application and avenues for future developments. With rising consumer demand for natural products, a greener and cleaner technology, i.e., ultrasound-assisted extraction, has received immense attention given its effective and rapid isolation for nanocellulose compared to conventional methods. Nevertheless, the application of ultrasound on a commercial scale is limited due to the challenges associated with process optimization, high energy requirement, difficulty in equipment design and process scale-up, safety and regulatory issues. This review aims to narrow the research gap by placing the current research activities into perspectives and highlighting the diversified applications, significant roles, and potentials of ultrasound to ease future developments. In recent years, enhancements have been reported with ultrasound assistance, including a reduction in extraction duration, minimization of the reliance on harmful chemicals, and, most importantly, improved yield and properties of nanocellulose. An extensive review of the strengths and weaknesses of ultrasound-assisted treatments has also been considered. Essentially, the cavitation phenomena enhance the extraction efficiency through an increased mass transfer rate between the substrate and solvent due to the implosion of microbubbles. Optimization of process parameters such as ultrasonic intensity, duration, and frequency have indicated their significance for improved efficiency. [ABSTRACT FROM AUTHOR]

Polysaccharides of β- d -glucan configuration have well-known antioxidant activity against reactive free radicals generated from the oxidation of metabolic processes. In this study, β- d -glucan-polysaccharides extracted from Ganoderma lucidum were incorporated in palm olein based nanoemulsions which act as carrier systems to enhance the delivery and bioactivity of these polysaccharides and could be potentially useful for skin care applications. Initially response surface statistical design (Central Composite Design – CCD) was subjected to optimize the formulation variables of oil-in-water (O/W) nanoemulsions induced by ultrasound. The optimal formulation variables as predicted by CCD resulted in considerably improving the physical characteristics of ultrasonically formulated nanoemulsions by minimizing their droplet size, polydispersity index and viscosity. Moreover, the β- d -glucan-loaded nanoemulsions exhibited good stability over 90 days under different storage conditions (4 °C and 25 °C). The studies using palm olein based β- d -glucan-loaded nanoemulsion generated using ultrasound confirm higher antioxidant activity as compared to free β- d -glucan. [ABSTRACT FROM AUTHOR]

This investigation focuses on activated carbon (AC) adsorption and ultrasound (US) cavitation for polishing the palm oil mill effluent (POME). Both AC adsorption and US cavitation were investigated individually, in series and operating them in a combined way. The efficiency of above processes has been evaluated in terms of removal of chemical oxygen demand (COD) and total suspended solids (TSS). For the individual operation, the optimisation studies were carried out by using the following conditions: AC dosage (50–200 g/L); contact time (2, 4, 6 h); US power amplitude (50% and 80%) and US cavitation time (30–180 min). The optimisation studies utilising US power amplitude (50%) and cavitation time (15 min) followed by AC adsorption using minimum AC dosage (50 g/L) and contact time (30 min) resulted in ∼100% COD and 83.33% TSS removals which meets the discharge limits set by the Department of Environment (DoE), Malaysia. The hybrid operation was also studied by simultaneously employing AC adsorption and US cavitation and it was observed that an adsorption dosage of 50 g/L resulted into achieving 73.08% COD and 98.33% TSS removals within 15 min of US irradiation. With the possibility of continuous and feasible sonochemical reactors, this hybrid approach of US cavitation followed by AC adsorption could be an alternative processing technique for POME polishing. [ABSTRACT FROM AUTHOR]

Ethanol separation from binary ethanol–water mixture by utilizing “ultrasonic atomization” or ‘ultrasonic distillation’ has been investigated and inferred as a case of evaporation. It was assumed that the operation of ultrasonic transducer reveals itself as mechanical agitation where the ultrasonic energy is ultimately regarded as heat input into the separation unit. Thus the local deviations from non-equilibrium owing to the propagation of ultrasonic waves through the bulk liquid were excluded from consideration. The process is accompanied by an enlargement of total vapor–liquid interfacial area due to the generation of atomized mist droplets that are supposed to have the same composition as that of bulk liquid. It contradicts with the previous concept of ‘ultrasonic distillation’ where the mist droplets were characterized by a higher percentage of volatile (ethanol) fraction. Consequently, this study demonstrates that ethanol enrichment process reported earlier might still be assessed by assuming that initial mist droplets have the same composition as that of the bulk liquid mixture. Thus, either by ultrasonic distillation or by bubbling carrier gas through the bulk liquid or even blowing it over the surface of the liquid, the conversion of liquid into vapour phase occurs and could be interpreted as equivalent to evaporation phenomena. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrasound disrupted macroporous resins can be recycled for adsorption. • Mild sonication during adsorption strengthened the influence of surface diffusion. • Intensive ultrasound pretreatment weakened the contribution of surface diffusion. • Bubble dynamics and sonochemical reactions under sonication were calculated. • Relationships between mass transfer behavior and bubble properties were established. Ultrasound is efficient to enhance various mass transfer processes. This study demonstrates that both ultrasound pretreatment and ultrasonication during adsorption promote the physisorption of polyphenols. The time to reach the adsorption equilibrium was shortened by more than 90 % when the resin diameter deceased from 592 μm to 60.23 μm in the intensive ultrasound pretreatment. The mass transfer mechanism of adsorption under mild sonication differs from that of adoption with intensive ultrasound pretreatment. Mild sonication during adsorption strengthens the influence of surface diffusion of polyphenols on intraparticle diffusion. In contrast, severe disruption of resin particles due to intensive ultrasound pretreatment weakens the surface diffusivity of polyphenols and reduces the contribution of surface diffusion. Also, the physics and sonochemistry of cavitation under sonication environments were explored. Under intensive and mild ultrasound treatments, the calculated bubble numbers were approximately 18789 L-1 and 6312 L-1, respectively. Moreover, a relationship was established between adsorption capacity from mass transfer modeling and bubble properties including the bubble collapse pressure, bubble number, processing time, and processing scale. This bridge between mass transfer behavior and properties of bubbles provides guidance and new insight for the design and scale-up of the ultrasound-assisted adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrasound (US) is a powerful synthesis method for a multitude of nanobiomaterials. • US-synthesised nanobiomaterials display better properties and performance. • Top-down and bottom-up nanobiomaterials synthesis are evaluated. • Mechanisms involved in the synthesis process are discussed. • Main challenges of US-synthesised nanobiomaterials are addressed. Ultrasound (US) demonstrates remarkable potential in synthesising nanomaterials, particularly nanobiomaterials targeted towards biomedical applications. This review briefly introduces existing top-down and bottom-up approaches for nanomaterials synthesis and their corresponding synthesis mechanisms, followed by the expounding of US-driven nanomaterials synthesis. Subsequently, the pros and cons of sono-nanotechnology and its advances in the synthesis of nanobiomaterials are drawn based on recent works. US-synthesised nanobiomaterials have improved properties and performance over conventional synthesis methods and most essentially eliminate the need for harsh and expensive chemicals. The sonoproduction of different classes and types of nanobiomaterials such as metal and superparamagnetic nanoparticles (NPs), lipid- and carbohydrate-based NPs, protein microspheres, microgels and other nanocomposites are broadly categorised based on the physical and/or chemical effects induced by US. This review ends on a good note and recognises US-driven synthesis as a pragmatic solution to satisfy the growing demand for nanobiomaterials, nonetheless some technical challenges are highlighted. [ABSTRACT FROM AUTHOR]