The crystallographic plane of the ZnO nanocrystals photocatalyst is considered as a key parameter for an effective photocatalysis, photoelectrochemical reaction and photosensitivity. In this paper, we report a simple method for the synthesis of a new (101) high-energy plane bounded ZnO nanocubes photocatalyst directly on the FTO surface, using a seed-mediated ultrasonic assisted hydrolysis process. In the typical procedure, high-density nanocubes and quasi-nanocubes can be grown on the substrate surface from a solution containing equimolar (0.04 M) zinc nitrate hydrate and hexamine. ZnO nanocubes, with average edge-length of ca. 50 nm, can be obtained on the surface in as quickly as 10 min. The heterogeneous photocatalytic property of the sample has been examined in the photodegradation of methyl orange (MO) by UV light irradiation. It was found that the ZnO nanocubes exhibit excellent catalytic and photocatalytic properties and demonstrate the photodegradation efficiency as high as 5.7 percent/μg mW. This is 200 times higher than those reported results using a relatively low-powered polychromatic UV light source (4 mW). The mechanism of ZnO nanocube formation using the present approach is discussed. The new-synthesized ZnO nanocubes with a unique (101) basal plane also find potential application in photoelectrochemical devices and sensing.
Ultrasonic VialTweeter is used for the sonication of small volume samples. It contains a titanium block with 8 holes for vial insertion, to be used simultaneously for batch operation. In this investigation, the ultrasonic and sonochemical performance of ultrasonic VialTweeter has been evaluated at its different positions. Experimental results using calorimetry, ultrasonic capillary effect, sonochemiluminescence and degradation of Rhodamine B showed that the sonochemical activity differs greatly at different positions along the VialTweeter, with positions 3 and 4 showing the maximum efficiency whereas the positions 1 and 2 being the least effective positions. These results were further verified by acoustic pressure simulation, confirming that certain locations in the VialTweeter may not perform in the same way as others due to the variation in acoustic pressure at different locations.
In this study, high-frequency ultrasound wave (1.8 MHz) at low intensity was applied to improve activated sludge settleability at high MLSS concentration. The effect of irradiation intensity, sonication mode, MLSS concentration and sample volume on the physical characteristics of sludge in a pilot scale settling column were investigated for optimizing the conditions. The obtained results showed that high-frequency ultrasound decreased the height of sludge (44%) and effluent turbidity (82.2%) and increased sludge settling velocity about 3 times at high biomass concentration. Irradiation intensity of 0.4 w/cm2 and sonication mode with interval times of 10 s showed the best results on the performance of the system at MLSS concentration of 8000 mg/L with a sample volume of 3 L.
This study investigates the potential of using small amounts of ionic liquids (IL) to enhance ultrasound-assisted extraction of lipids content from green microalgae. Three imidazolium-based ILs (butyl, octyl and dodecyl), each of them with two anions (bromide and acetate) were tested as additives. Viscosity and surface tension of the ILs aqueous mixtures were analyzed to determine the influence of ILs' anions and alkyl chain length, whereas KI dosimetry experiments were used as an indicator of radicals formation. A key finding suggests that the small addition of ILs improves the ultrasonication either by enhancing the viscosity and reducing the water surface tension, leading to a more powerful acoustic cavitation process or by increasing HO° production likely to oxidize the microalgae cells membranes, and consequently disrupting them on a more efficient manner. KI dosimetry also revealed that long ILs alkyl chain is detrimental. This experimental observation is confirmed thus strengthened as the yield of extracted lipids from green microalgae has shown an incremental trend when the IL concentration also increased. These hypotheses are currently under investigation to spot detailed impact of ILs on cavitation process.
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.
Sequentially precipitated Mg-promoted nickel-silica catalysts with ageing performed under various ultrasonic intensities were employed to study the catalyst performance in the partial hydrogenation of sunflower oil. Results from various characterisation studies showed that increasing ultrasonic intensity caused a higher degree of hydroxycarbonate erosion and suppressed the formation of Ni silicates and silica support, which improved Ni dispersion, BET surface area and catalyst reducibility. Growth of silica clusters on the catalyst aggregates were observed in the absence of ultrasonication, which explained the higher silica and nickel silicate content on the outer surface of the catalyst particle. Application of ultrasound also altered the electron density of the Ni species, which led to higher activity and enhanced product selectivity for sonicated catalysts. The catalyst synthesised with ultrasonic intensity of 20.78 Wcm-2 achieved 22.6% increase in hydrogenation activity, along with 28.5% decrease in trans-C18:1 yield at IV = 70, thus supporting the feasibility of such technique.
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.
This paper presents the successful application of ultrasound-assisted packed-bed (UAE-PB) method for the extraction of hypericin from the Hypericum perfuratum L. The Soxhlet system was utilized for the determination of suitable solvent from ethanol, methanol or from the mixture of different proportions of ethanol-methanol. The mixture of 50:50 v/v ethanol-methanol was obtained to be the most suitable solvent since it led to the highest extraction amount of hypericin. The extraction amount of hypericin increased by 13.6% and 21.4% when the solvent changed from pure methanol to the mixture of 50:50 v/v ethanol-methanol for the extraction time of 3 and 8 h, respectively. Subsequently, the extraction was conducted through the UAE-PB, and the effects of temperature, time, and the ratio of solvent to the dried plant were studied. The response surface method (RSM) was used to investigate the effect of parameters on the extraction in the UAE-PB system. At the temperature of 60 °C, extraction time of 105 min, and the solvent to plant ratio of 15.3, the maximum extraction yield of hypericin was achieved. In the optimal conditions, the amount of extraction was 0.112 mg hypericin/g dried plant, which was in accordance with the optimized predicted value (0.111 mg hypericin/g dried plant) from Design-Expert software.
A rapid and green method for the synthesis of novel N-thiazolidine-2,4-dione isoxazoline derivatives 5 from N-allyl-5-arylidenethiazolidine-2,4-diones 3 as dipolarophiles with arylnitrile oxides via 1,3-dipolar cycloaddition reaction. The corresponding N-allyl substituted dipolarophiles were prepared by one-pot method from thiazolidine-2,4-dione with aldehydes using Knoevenagel condensation followed by N-allylation of thiazolidine-2,4-dione in NaOH aqueous solution under sonication. In addition, the isoxazoline derivatives 5 were synthesized by regioselective and chemoselective 1,3-dipolar cycloaddition using inexpensive and mild NaCl/Oxone/Na3PO4 as a Cl source, oxidant and/or catalyst under ultrasonic irradiation in EtOH/H2O (v/v, 2:1) as green solvent. All synthesized products are furnished in good yields in the short reaction time, and then their structures were confirmed by NMR, mass spectrometry and X-ray crystallography analysis.
The optimisation of the Ultrasound-Assisted Extraction (UAE) method was investigated by employing the Central Composite Rotatable Design (CCRD) of Response Surface Methodology (RSM). The UAE method was based on a simple ultrasound treatment using methanol as the extraction medium to facilitate the cell disruption of Mitragyna speciosa leaves for optimum extraction yield and Total Phenolic Content (TPC). Three different parameters comprising extraction temperature (X1: 25-50 °C), sonication time (X2: 15-50 min), and solvent to solid ratio (X3: 10-30 mL/g), and were selected as the independent variables, while two response variables were selected, namely extraction yield (Y1) and TPC (Y2). Based on the results, the developed quadratic polynomial model correlated with the experimental data is based on the coefficient of determination (R2) of extraction yield (0.9972, p
Pandan (Pandanus amaryllifolius) is commonly used as a food ingredient in Southeast Asia due to its delicious flavor, appetizing aroma and bright green colour. Pandan plant is uniquely found only in certain parts of the world. Despite its increasing popularity worldwide, its export market is limited by practical issues. One of the main problems for exporting Pandan to global market is its stability during transport. Due to the volatility of its active constituent, the functional properties of Pandan are lost during storage and shipment. In this study, we explored the ability of ultrasound processing technology to encapsulate the aromatic Pandan extract using lysozyme or chitosan as a shell material. 20 kHz ultrasonicator was used to encapsulate the pandan extract at 150 W of applied power. Two parameters, the ultrasonic probe tip and the core-to-shell ratio were varied to control the properties of the encapsulates. The diameters of the probe tip used were 0.3 and 1.0 cm. The core-to-shell volume ratios used were 1:160 and 1:40. The size distribution and the stability of the synthesized microspheres were characterized to understand and explore the possible parameters variation impact. Both size and size distribution of the microspheres were found to be influenced by the parameters varied to certain extent. The results showed that the mean size of the microspheres was generally smallest when using 1 cm probe tip with lower core-to-shell volume ratio but largest when using the 3 mm tip with higher core-to-shell volume ratio. This indicates that the sonication parameters could be fine-tuned to achieve the encapsulation of Pandan extract for storage and export. The pandan-encapsulated microspheres were also found to be stable during storage at least for one month.
CO2flooding process as a common enhanced oil recovery method may suffer from interface instability due to fingering and gravity override, therefore, in this study a method to improve the performance of CO2flooding through an integrated ultraosund-CO2flooding process is presented. Ultrasonic waves can deliver energy from a generator to oil and affect its properties such as internal energy and viscosity. Thus, a series of CO2flooding experiments in the presence of ultrasonic waves were performed for controlled and uncontrolled temperature conditions. Results indicate that oil recovery was improved by using ultrasound-assisted CO2flooding compared to conventional CO2flooding. However, the changes were more pronounced for uncontrolled temperature conditions of ultrasound-assisted CO2flooding. It was found that ultrasonic waves create a more stable interface between displacing and displaced fluids that could be due to the reductions in viscosity, capillary pressure and interfacial tension. In addition, higher CO2injection rates, increases the recovery factor in all the experiments which highlights the importance of injection rate as another factor on reduction of the fingering effects and improvement of the sweep efficiency.
The aim of this study was ultrasound assisted removal of Ceftriaxone sodium (CS) based on CCD model. Using sonochemical synthesized Bi2WO6 implanted on graphitic carbon nitride/Multiwall carbon nanotube (g-C3N4/MWCNT/Bi2WO6). For this purpose g-C3N4/MWCNT/Bi2WO6 was synthesized and characterized using diverse approaches including XRD, FE-SEM, XPS, EDS, HRTEM, FT-IR. Then, the contribution of conventional variables including pH, CS concentration, adsorbent dosage and ultrasound contact time were studied by central composite design (CCD) under response surface methodology (RSM). ANOVA was employed to the variable factors, and the most desirable operational conditions mass provided. Drug adsorption yield of 98.85% obtained under these defined conditions. Through conducting five experiments, the proper prediction of the optimum point were examined. The respective results showed that RSD% was lower than 5% while the t-test confirmed the high quality of fitting. Langmuir isotherm equation fits the experimental data best and the removal followed pseudo-second order kinetics. The estimation of the experimentally obtained maximum adsorption capacities was 19.57 mg.g- of g-C3N4/MWCNT/Bi2WO6 for CS. Boundary layer diffusion explained the mechanism of removal via intraparticle diffusion.
This study aimed to evaluate the effect of ultrasound treatment on the cholesterol removing ability of lactobacilli. Viability of lactobacilli cells was significantly increased (P < 0.05) immediately after treatment, but higher intensity of 100 W and longer duration of 3 min was detrimental on cellular viability (P < 0.05). This was attributed to the disruption of membrane lipid bilayer, cell lysis and membrane lipid peroxidation upon ultrasound treatment at higher intensity and duration. Nevertheless, the effect of ultrasound on membrane properties was reversible, as the viability of ultrasound-treated lactobacilli was increased (P < 0.05) after fermentation at 37 °C for 20 h. The removal of cholesterol by ultrasound-treated lactobacilli via assimilation and incorporation of cholesterol into the cellular membrane also increased significantly (P < 0.05) upon treatment, as observed from the increased ratio of membrane C:P. Results from fluorescence anisotropies showed that most of the incorporated cholesterol was saturated in the regions of phospholipids tails, upper phospholipids, and polar heads of the membrane bilayer.
Recently, chitin and chitosan are widely investigated for food preservation and active packaging applications. Chemical, as well as biological methods, are usually adopted for the production of these biopolymers. In this study, modification to a chemical method of chitin synthesis from shrimp shells has been proposed through the application of high-frequency ultrasound. The impact of sonication time on the deproteinization step of chitin and chitosan preparation was examined. The chemical identities of chitin and chitosan were verified using infrared spectroscopy. The influence of ultrasound on the deacetylation degree, molecular weight and particle size of the biopolymer products was analysed. The microscopic characteristics, crystallinity and the colour characteristics of the as-obtained biopolymers were investigated. Application of ultrasound for the production of biopolymers reduced the protein content as well as the particle size of chitin. Chitosan of high deacetylation degree and medium molecular weight was produced through ultrasound assistance. Finally, the as-derived chitosan was applied for beef preservation. High values of luminosity, chromatid and chrome were noted for the beef samples preserved using chitosan films, which were obtained by employing biopolymer subjected to sonication for 15, 25 and 40 min. Notably; these characteristics were maintained even after ten days of packaging. The molecular weight of these samples are 73.61 KDa, 86.82 KDa and 55.66 KDa, while the deacetylation degree are 80.60%, 92.86% and 94.03%, respectively; in the same order, the particle size of chitosan are 35.70 μm, 25.51 μm and 20.10 μm.
The aim of this study was to evaluate the effect of ultrasound on the intestinal adherence ability, cell growth, and cholesterol removal ability of parent cells and subsequent passages of Lactobacillus fermentum FTDC 1311. Ultrasound significantly decreased the intestinal adherence ability of treated parent cells compared to that of the control by 11.32% (P<0.05), which may be due to the protein denaturation upon local heating. Growth of treated parent cells also decreased by 4.45% (P<0.05) immediately upon ultrasound (0-4h) and showed an increase (P<0.05) in the viability by 2.18-2.34% during the later stage of fermentation (12-20 h) compared to that of the control. In addition, an increase (P<0.05) in assimilation of cholesterol (>9.74%) was also observed for treated parent cells compared to that of the control, accompanied by increased (P<0.05) incorporation of cholesterol into the cellular membrane. This was supported by the increased ratio of membrane cholesterol:phospholipids (C:P), saturation of cholesterol in the apolar regions, upper phospholipids regions, and polar regions of membrane phospholipids of parent cells compared to that of the control (P<0.05). However, such traits were not inherited by the subsequent passages of treated cells (first, second, and third passages). Our data suggested that ultrasound treatment could be used to improve cholesterol removal ability of parent cells without inducing permanent damage/defects on treated cells of subsequent passages.
Degradation of xanthan polymer in aqueous solution by ultrasonic irradiation was investigated. The effects of selected variables i.e. sonication intensity, irradiation time, concentration of xanthan gum and molar concentration of NaCl in solution were studied. Combined approach of full factorial design and conventional one-factor-at-a-time was applied to obtain optimum degradation at sonication power intensity of 11.5Wcm-2, irradiation time 120min and 0.1gL-1xanthan in a salt-free solution. Molecular weight reduction of xanthan gum under sonication was described by an exponential decay function with higher rate constant for polymer degradation in the salt free solution. The limiting molecular weight where fragments no longer undergo scission was determined from the function. The incorporation of NaCl in xanthan solution resulted in a lower limiting molecular weight. The ultrasound-mediated degradation of aqueous xanthan polymer chain agreed with a random scission model. Side chain of xanthan polymer is proposed to be the primary site of scission action.
Ultrasonic irradiation greatly improved the Candida antarctica lipase B mediated ring opening polymerization of ε-caprolactone to poly-6-hydroxyhexanoate in the ionic liquid 1-ethyl-3-methylimidazolium tetraflouroborate. Compared to the conventional nonsonicated reaction, sonication improved the monomer conversion by 63% and afforded a polymer product of a narrower molecular weight distribution and a higher degree of crystallinity. Under sonication, the polydispersity index of the product was ~1.44 compared to a value of ~2.55 for the product of the conventional reaction. With sonication, nearly 75% of the monomer was converted to product, but the conversion was only ~16% for the reaction carried out conventionally. Compared to conventional operation, sonication enhanced the rate of polymer propagation by >2-fold and the turnover number of the lipase by >3-fold.
An upsurge in sustainable energy demands has ultimately made supercapattery one of the important choice for energy storage, owing to highly advantageous energy density and long life span. In this work, novel strontium based mixed phased nanostructures were synthesized by using probe sonicator with sonication power 500 W at frequency of 20 kHz. The synthesized material was subsequently calcined at different temperature ranging from 200 to 800 °C. Structural and morphological analysis of the synthesized materials reveals the formation of mixed particle and rod like nanostructures with multiple crystal phases of strontium oxides and carbonates. Crystallinity, grain size and morphology of grown nanomaterials significantly improved with the increase of calcination temperature due to sufficient particle growth and low agglomeration. The electrochemical performance analysis confirms the redox activeness of the Sr-based electrode materials. Material calcined at 600 °C show high specific capacitance of 350 F g-1 and specific capacity of 175 C g-1 at current density of 0.3 A g-1 due to less particle agglomeration, good charge transfer and more contribution of electrochemical active sites for redox reactions. In addition, the developed supercapattery of Sr-based nanomaterials//activated carbon demonstrated high performance with maximum energy density of 21.8 Wh kg-1 and an excellent power density of 2400 W kg-1 for the lower and higher current densities. Furthermore, the supercapattery retain 87% of its capacity after continuous 3000 charge/discharge cycles. The device characteristics were further investigated by analyzing the capacitive and diffusion controlled contributions. The versatile strategy of developing mixed phased nanomaterials pave the way to synthesize other transition metal based nanomaterials with superior electrochemical performance for hybrid energy storage devices.
Optimum ultrasonication time will lead to the better performance for heat transfer in addition to preparation methods and thermal properties of the nanofluids. Nano particles are dispersed in base fluids like water (water-based fluids), glycols (glycol base fluids) &oils at different mass or volume fraction by using different preparation techniques. Significant preparation technique can enhance the stability, effects various parameters & thermo-physical properties of fluids. Agglomeration of the dispersed nano particles will lead to declined thermal performance, thermal conductivity, and viscosity. For better dispersion and breaking down the clusters, Ultrasonication method is the highly influential approach. Sonication hour is unique for different nano fluids depending on their response to several considerations. In this review, systematic investigations showing effect on various physical and thermal properties based on ultrasonication/ sonication time are illustrated. In this analysis it is found that increased power or time of ideal sonication increases the dispersion, leading to higher stable fluids, decreased particle size, higher thermal conductivity, and lower viscosity values. Employing the ultrasonic probe is substantially more effective than ultrasonic bath devices. Low ultrasonication power and time provides best outcome. Various sonication time periods by various research are summarized with respect to the different thermophysical properties. This is first review explaining sonication period influence on thermophysical properties of graphene nanofluids.