| 1. |
- Chen, Yuran, et al.
(författare)
-
Effect of the ultrasonic standing wave frequency on the attractive mineralization for fine coal particle flotation
- 2021
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 77
-
Tidskriftsartikel (refereegranskat)abstract
- Froth flotation for mineral beneficiation is one of the most important separation techniques; however, it has several challenges for processing fine and ultrafine particles. Attractive mineralization between particles and bubbles by ultrasonic standing wave (USW) is a novel and high-efficiency method that could assist fine particle flotation. Frequency is an important ultrasound parameter, whose effectiveness mechanisms on the attractive mineralization did not compressively address. This study explored the effect of the USW field with various frequencies on the fine coal flotation for filling this gap. Herein, a high-speed camera and a focused beam reflectance measurement (FBRM) were used to analyze three sub-processes of the attractive mineralization, including the microbubbles’ formation, the conventional flotation bubbles (CFBs)’ dispersion, and the particles’ movement. It was found that the maximum flotation metallurgical responses were obtained under the highest examined USW frequency (600 kHz). However, the flotation outcomes by a low USW frequency (50 kHz) were even lower than the conventional flotation tests. Observation and theoretical calculation results revealed these results were originated from the influence of frequency on the carrier bubbles’ formation and the action of the secondary acoustic force during USW-assisted flotation. These outcomes demonstrated that frequency is a key factor determining the success of attractive mineralization for fine particles’ flotation.
|
|
| 2. |
- Gao, Jixuan, et al.
(författare)
-
Pickering emulsion prepared by nano-silica particles – A comparative study for exploring the effect of various mechanical methods
- 2022
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 83
-
Tidskriftsartikel (refereegranskat)abstract
- Pickering emulsions are eco-friendly, stabilized by solid particles, and have an essential role in leading industries. Although Pickering emulations have found several applications, surprisingly few investigations have attempted to explore the effectiveness of various mechanical processes for its production. To fill these gaps, the present investigation comprehensively examined the application of various Pickering emulsion preparation processes such as rotor-stator homogenization emulsification (R-SH), ultrasonic emulsification, and their combined processes by using nano-silica particles. The influences of emulsification time and intensity on emulsion droplets' distribution were analyzed as indicative factors. The kerosene/water nano-silica Pickering emulsion was utilized for all assessments. The obtained results demonstrated that the main distribution peak of the emulsion prepared by R-SH occurred where the chord length was greater than 40 μm. Micro-scale nano-silica-aggregates generated large droplets, while the fine-emulsion fraction was significantly increased after ultrasonic treatment. The experimental results showed that the emulsion prepared only by ultrasound needed substantial power to form a Pickering emulsion since the oil phase was difficult to disperse in the water phase. Finally, it was concluded that preprocessing by R-SH could form a stable and uniform emulsion speedily, which is essential for ultrasound emulsion preparation.
|
|
| 3. |
- Johansson, Örjan, 1963-, et al.
(författare)
-
Extraction of tungsten from scheelite using hydrodynamic and acoustic cavitation
- 2021
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 71
-
Tidskriftsartikel (refereegranskat)abstract
- The primary purpose of this study is to investigate the effects of hydrodynamic and acoustic cavitation (HAC) on the leaching efficiency of tungsten. The aim is to reduce energy use and to improve the recovery rate. The goal is also to carry out a leaching process at a much lower temperature than in an autoclave process that is currently used in the industry. Energy-efficient initiation and collapse of cavitation bubbles require optimization of (i) vibro-acoustic response of the reactor structure, (ii) multiple excitation frequencies adapted to the optimized reactor geometry, and (iii) hydrodynamic cavitation with respect to orifice geometry and flow conditions. The objective is to modify and apply a previously in house developed high power cavitation reactor in order to recover tungsten by leaching of the dissolution of scheelite in sodium hydroxide. In this process, various experimental conditions like dual-frequency excitation, different orifice geometry have been investigated. The numerically optimized reactor concept was excited by two frequencies 23 kHz and 39–43 kHz in various flow conditions. The effects of leaching time, leaching temperature, ultrasonic power and geometry of orifice plates have been studied. The leaching temperature was varied from 40 °C to 80 °C. The concentration of leaching reagent sodium hydroxide (NaOH) was 10 mol/L.The results were compared to conventional chemical leaching. Energy supplement with acoustic cavitation of 130 kWh/kg concentrate resulted in a leaching recovery of tungsten (WO3) of 71.5%, compared to 36.7% obtained in absence of ultrasound. The results confirm that the method developed is energy efficient and gives a recovery rate potentially better than current autoclave technology.
|
|
| 4. |
- Maghami, Sara, 1989-, et al.
(författare)
-
Structural acoustic design of a sonicator to enhance energy transfer efficiency
- 2024
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 103
-
Tidskriftsartikel (refereegranskat)abstract
- The study focuses on developing a comprehensive design approach for a flow-through ultrasonic reactor (sonicator) to tackle challenges like low energy transfer efficiency and unstable system performance. The simulation accounts for structural vibrations, structural-fluid interactions, and pressure distributions within the cavitation zone under single-frequency excitation. Different geometrical designs of cylindrical sonicators are analyzed, with input parameters tailored to acquire higher acoustic cavitation intensity. The findings reveal a novel hexagonal ring-shaped excitation structure that reduces coupling losses, ensures uniform acoustic pressure distribution, and generates symmetric vibration mode shapes. The study emphasizes the separation of parasitic modes from the desired resonance frequency response and simulates the influence of bubbly liquid properties through complex wave numbers and harmonic responses. Experimental validation on a manufactured prototype, including mechanical and electrical impedance, sound pressure spectrum, and cavitation intensity, supports the simulated results. Ultimately, the sonicator exhibits three feasible resonance frequencies to be used pairwise at the certain temperature and input power interval for different applications.
|
|
| 5. |
- Naghdi, Shahab, et al.
(författare)
-
Ultrasonic-assisted enzymatic extraction of sulfated polysaccharide from Skipjack tuna by-products
- 2023
-
Ingår i: Ultrasonics Sonochemistry. - : Elsevier BV. - 1873-2828 .- 1350-4177. ; 95
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of ultrasound pretreatment on extraction efficiency of sulfate polysaccharides (SPs) using alcalase from different by-products of Skipjack tuna including head, bone and skin was evaluated. Structural, functional, antioxidant and antibacterial properties of the recovered SPs using the ultrasound-enzyme and enzymatic method were also investigated. Ultrasound pretreatment significantly increased the extraction yield of SPs from all the three by-products compared with the conventional enzymatic method. All extracted SPs showed high antioxidant potential in terms of ABTS, DPPH and ferrous chelating activities where the ultrasound treatment enhanced antioxidant activities of the SPs. The SPs exerted strong inhibiting activity against various Gram-positive and Gram-negative bacteria. The ultrasound treatment remarkably increased antibacterial activity of the SPs against L. monocytogenes but its effect on other bacteria was dependent on the source of the SPs. Altogether, the results suggest that ultrasound pretreatment during enzymatic extraction of SPs from tuna by-products can be a promising approach to improve extraction yield but also bioactivity of the extracted polysaccharides.
|
|
| 6. |
- Pamidi, Taraka Rama Krishna, et al.
(författare)
-
Comparison of two different ultrasound reactors for the treatment of cellulose fibers
- 2020
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 62
-
Tidskriftsartikel (refereegranskat)abstract
- The pulp and paper industry is in continuous need for energy-efficient production processes. In the refining process of mechanical pulp, fibrillation is one of the essential unit operations that count for up to 80% of the total energy use. This initial study explores the potential and development of new type of scalable ultrasound reactor for energy efficient mechanical pulping. The developed reactor is of continuous flow type and based on both hydrodynamic and acoustic cavitation in order to modify the mechanical properties of cellulose fibers. A comparison of the prototype tube reactor is made with a batch reactor type where the ultrasonic horn is inserted in the fluid. The pulp samples were sonicated by high-intensity ultrasound, using tuned sonotrodes enhancing the sound pressure and cavitation intensity by a controlled resonance in the contained fluid. The resonant frequency of the batch reactor is 20.8 kHz and for the tube reactor it is 22.8 kHz. The power conversion efficiency for the beaker setup is 25% and 36% in case of the tube reactor in stationary mode. The objective is to verify the benefit of resonance enhanced cavitation intensity when avoiding the effect of Bjerkenes forces. The setup used enables to keep the fibers in the pressure antinodes of the contained fluid. In case of the continuous flow reactor the effect of hydrodynamic cavitation is also induced. The intensity of the ultrasound in both reactors was found to be high enough to produce cavitation in the fluid suspension to enhance the fiber wall treatment. Results show that the mechanical properties of the fibers were changed by the sonification in all tests. The continuous flow type was approximately 50% more efficient than the beaker. The effect of keeping fibers in the antinode of the resonant mode shape of the irradiation frequency was also significant. The effect on fiber properties for the tested mass fraction was determined by a low-intensity ultrasound pulse-echo based measurement method, and by a standard pulp analyzer.
|
|
| 7. |
- Patel, Alok, Dr. 1989-, et al.
(författare)
-
A comparative study on de novo and ex novo lipid fermentation by oleaginous yeast using glucose and sonicated waste cooking oil
- 2019
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 52, s. 364-374
-
Tidskriftsartikel (refereegranskat)abstract
- There are only a few reports available about the assimilation of hydrophobic substrates by microorganisms, however, it is well known that oleaginous microorganisms are capable of utilizing both hydrophilic and hydrophobic substrates and accumulate lipids via two different pathways namely de novo and ex novo lipid synthesis, respectively. In the present study, an oleaginous yeast, Cryptococcus curvatus, was investigated for its potentials to utilize a waste substrate of hydrophobic nature (waste cooking oil – WCO) and compared with its ability to utilize a hydrophilic carbon source (glucose). To facilitate the utilization of WCO by C. curvatus, the broth was sonicated to form a stable oil-in-water emulsion without adding any emulsifier, which was then compared with WCO samples without any ultrasound treatment (unsonicated) for the yeast cultivation. Ultrasonication reduces the size of hydrophobic substrates and improves their miscibility in an aqueous broth making them easily assimilated by oleaginous yeast. Under de novo lipid fermentation, the yeast synthesized 9.93 ± 0.84 g/L of cell dry weight and 5.23 ± 0.49 g/L lipids (lipid content of 52.66 ± 0.93% w/w) when cultivated on 40 g/L of glucose (C/N ratio of 40). The amount of cell dry weight, lipid concentration, and lipid content were considerably higher during the ex novo lipid synthesis. More specifically, the highest lipid content achieved was 70.13 ± 1.65% w/w with a corresponding dry cell weight and lipid concentration of 18.62 ± 0.76 g/L and 13.06 ± 0.92 g/L respectively, when grown on 20 g/L sonicated WCO. The highest lipid concentration, however, was observed when the yeast was cultivated on 40 g/L sonicated WCO. Under these conditions, 20.34 g/L lipids were produced with a lipid content of 57.05% w/w. On the other hand, lipid production with unsonicated WCO was significant lower, reaching 11.16 ± 1.02 g/L (69.14 ± 1.34% w/w of lipid content) and 12.21 ± 1.34 g/L (47.39 ± 1.67% w/w of lipid content) for 20 g/L and 40 g/L of WCO, respectively. This underpins the significance of the sonication treatment, especially at elevated WCO concentrations, to improve the accessibility of the yeast to the WCO. Sonication treatment that was used in this study assisted the utilization of WCO without the need to add emulsifiers, thus reducing the need for chemicals and in turn has a positive impact on the production costs. The microbial lipids produced presented a different fatty acid composition compared to the WCO, making them more suitable for biodiesel production as suggested by the theoretical estimation of the biodiesel properties.
|
|
| 8. |
- Patel, Alok, Dr. 1989-, et al.
(författare)
-
A novel rapid ultrasonication-microwave treatment for total lipid extraction from wet oleaginous yeast biomass for sustainable biodiesel production
- 2019
-
Ingår i: Ultrasonics sonochemistry. - : Elsevier. - 1350-4177 .- 1873-2828. ; 51, s. 504-516
-
Tidskriftsartikel (refereegranskat)abstract
- Oleaginous yeasts have emerged as a sustainable source of renewable oils for liquid biofuels. However, biodiesel production from them has few constraints with respect to their cell disruption and lipid extraction techniques. The lipid extraction from oleaginous yeasts commonly includes dewatering and drying of cell biomass, which requires energy and time. The aim of this work was to establish a process for the lipid extraction techniques from wet biomass applying acid catalyzed hot water, microwave, rapid ultrasonication-microwave treatment together with conventional Bligh and Dyer method. In the wake of testing all procedures, it was revealed that rapid ultrasonication-microwave treatment has great potential to give high lipid content (70.86 % w/w) on the cell dry weight basis. The lipid profile after treatment showed the presence of appropriate quantities of saturated (10.39 ± 0.15%), monounsaturated (76.55 ± 0.19%) and polyunsaturated fatty acids (11.49 ± 0.23%) which further improves biodiesel quality compared to the rest of methods. To the best of our knowledge, this is the first report of using rapid ultrasonication-microwave treatment for the lipid extraction from wet oleaginous yeast biomass in the literature.
|
|
| 9. |
- Pezeshk, Samaneh, et al.
(författare)
-
Impact of ultrasound on extractability of native collagen from tuna by-product and its ultrastructure and physicochemical attributes
- 2022
-
Ingår i: Ultrasonics Sonochemistry. - : Elsevier BV. - 1873-2828 .- 1350-4177. ; 89
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of ultrasound treatment (300 W; 0, 5, 10, 15, 20 and 25 min) on the extractability of acid soluble collagen from yellowfin tuna skin and its structural, physicochemical and functional properties were investigated. Ultrasound treatments significantly increased collagen extraction yield from the tuna skin up to 2.7 times, compared to the conventional extraction with acetic acid. The level of proline, hydroxyproline and thermal stability of collagens increased by applying ultrasound while their native triple-stranded helical structure was well-preserved, as revealed by X-ray diffraction and FTIR spectroscopy. However, ultrasound treatment reduced the particle size of the collagens which increased their pH and salt induced solubility. The water holding capacity and the emulsifying properties of ultrasound treated collagens were also higher than those produced with the conventional method. Altogether, the results suggested that ultrasonication can be a promising assistant technology for improving native collagen extraction efficiency from tuna skin and its functionality but its duration should be carefully optimized.
|
|
| 10. |
- Santschi, Michaela V., et al.
(författare)
-
Ultrasound-aided pH-shift processing for resource-smart valorization of salmon and herring side streams
- 2023
-
Ingår i: Ultrasonics Sonochemistry. - 1873-2828 .- 1350-4177. ; 99
-
Tidskriftsartikel (refereegranskat)abstract
- The possibility of reducing the amount of fresh water used during alkaline the pH-shift processing of salmon head (SH) and herring frame (HF) was evaluated with ultrasound (US) as a tool to mitigate its negative effects on protein yield. The role of water ratio and US for homogenate viscosity, mass yield, crude composition, functional properties and lipid oxidation of the SH and HF protein isolates were also investigated. Applying US during the solubilization step of the pH-shift process completely compensated for the reduced protein yield coming from using 3 rather than 6 volumes of water for HF, but not for SH. Using US had no negative effect on the composition and protein functionality of the HF protein isolate. However, it slightly increased its level of secondary lipid oxidation products. Altogether, applying US during the pH-shift processing at low water ratios can be a promising solution for more resource-smart valorization of herring side streams.
|
|
