Ultrasonics Sonochemistry最新文献

Zein-based films exhibit high efficiency in ethylene adsorption. However, its brittleness limits the practical applications. To address this issue, this study synergizes the plasticizing effects of high-intensity ultrasound (HIU) and castor oil (CO) to reduce the brittleness of zein-based films. The plasticizing mechanism was demonstrated through the formation of new intermolecular hydrogen bonds and electrostatic interactions, as evidenced by fourier transform infrared spectroscopy (FTIR) and zeta potential measurements. The tensile strength of 6 % CO-zein film increased eightfold. Additionally, the freshness of mangoes stored with 6 % CO-zein film significantly improved, extending their shelf life from 5 days to 15 days. Therefore, this study investigated the synergistic plasticization of zein-based films through the addition of CO, based on HIU. It also provides a theoretical basis for fruit packaging.

Metal additive manufacturing (AM) is a disruptive technology that provides unprecedented design freedom and manufacturing flexibility for the forming of complex components. Despite its unparalleled advantages over traditional manufacturing methods, the existence of fatal issues still seriously hinders its large-scale industrial application. Against this backdrop, U-FAAM is emerging as a focus, integrating ultrasonic energy into conventional metal AM processes to harness distinctive advantages. This work offers an up-to-date, specialized review of U-FAAM, articulating the integrated modes, mechanisms, pivotal research achievements, and future development trends in a systematic manner. By synthesizing existing research, it highlights future directions in further optimizing process parameters, expanding material applicability, etc., to advance the industrial application and development of U-FAAM technology.

In this study, we estimated the equilibrium bubble size of acoustic cavitation in a molten metal, which is basic information in ultrasonic casting. For this, the bubble shape instability of acoustic cavitation in the melt was numerically investigated by solving the Keller–Miksis equation and dynamic equation of the distortion amplitude. The acoustic cavitation bubbles are more stable in aluminum and magnesium melts than in water, and the parametric instability mainly determines the bubble stability at 20–160 kHz in molten metals. However, the afterbounce instability does not significantly affect the bubble stability in molten metals owing to the small number of bubble oscillations after the first rapid compression, and the distortion amplitude cannot grow significantly after the first compression. The bubbles in the melt become more unstable with an increase in the ultrasonic frequency owing to the corresponding increase in the bubble wall velocity. Through this stability analysis, we can estimate that the stable bubble size in the aluminum or magnesium melt is approximately three or four times larger than that in water at the same ultrasonic pressure amplitude.

Cavitation noise is the major noise in underwater, and the study of acoustic radiation from bubble clusters is the primary means to reveal the mechanism of cavitation noise. In this study, direct numerical simulation (DNS) of bubble clusters with volume fractions of 20–40 % with different bubble sizes and bubble position distributions are performed, and the far-field sound pressure is calculated using the Ffowcs Williams–Hawkings (FW-H) method. Then, we compare the collapse and acoustic radiation of bubble clusters with equivalent bubble. The results show that the collapse times of bubble clusters at the same volume fraction are identical and close to equivalent bubble, despite the different bubble sizes and positions in the bubble cluster. Further, in terms of acoustic radiation, the layered arrangement of bubble positions results in bubble clusters exhibiting layer-by-layer collapse and emitting multiple sound pressure pulses. In contrast, a random arrangement of bubble positions lacks this feature, resulting in the collapse of the bubble cluster without a layered phenomenon and radiating only a single primary sound pulse, which is consistent with the equivalent bubble. Additionally, the distribution of bubble sizes in the bubble cluster has almost no effect on the acoustic radiation of the bubble cluster. Notably, when the volumetric fraction exceeds 25 %, the sound pressure levels of bubble clusters with different distributions in the frequency domain are nearly identical, with differences from the equivalent bubble within 5 dB.

The accumulation of electric arc furnace slag (EAFS) in landfills has been causing severe environmental problems. This study examines the dissolution properties of EAFS minerals, including brownmillerite and gehlenite, essential for their possible use in resource recovery. An investigation was conducted to compare the effects of sonication and stirring on mineral dissolution while also assessing the usage of citrate as a complexing agent for gehlenite. Synthetic brownmillerite and gehlenite minerals were dissolved in aqueous solutions at room temperature using a 1:100 g/ml ratio. The dissolved elements were measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), while zeta potential and X-ray Photoelectron Spectroscopy (XPS) were used to assess changes in surface chemistry. Brownmillerite had significant dissolution extents, with Al and Ca dissolving up to 16 % and 8 %, respectively, in contrast to gehlenite, which dissolved less than 2 % under similar conditions. Sonication significantly increased the dissolution of brownmillerite by up to 100 %, although its impact on gehlenite dissolution varied depending on the duration of time. Besides, adding citrate enhanced the leaching of Al and Ca from gehlenite by facilitating complexation. XPS data demonstrated differences in elemental ratios on brownmillerite and gehlenite surfaces affected by the method used and the presence of citrate. Lastly, the dissolution extents of Al and Ca from EAFS were up to 12 %, depending on time and mixing method, with a preference for sonication over stirring. In conclusion, this study showed that minerals in EAFS have distinct dissolution characteristics, and sonication and citrate can considerably enhance dissolution.

Crystallization is an important process that affects the properties of final products and is essential in nearly all chemical processing industries. In recent years, ultrasonic technology has received widespread attention due to its ability to enhance crystallization yield, improve crystal morphology and shape, and regulate the particle size and distribution of crystal products. It holds promising prospects for industrial crystallization. In this work, the ultrasonic cavitation effect and ultrasonic crystallization mechanism are described, and the influence of ultrasound on the crystallization effect of products is analysed and discussed. In addition, the application status of ultrasonic reactors and ultrasonic crystallization processes is introduced in detail, and the change trend from laboratory to industrialization is analyzed. Finally, the challenges and opportunities facing the industrialization of ultrasonic crystallization in future developments are discussed. The purpose of this work is to make the selective promotion or inhibition of ultrasound more helpful for industrial crystallization.

How to precisely control and efficiently utilize the physical processes such as high temperature, high pressure, and shockwaves during the collapse of cavitation bubbles is a focal concern in the field of cavitation applications. The viscosity change of the liquid will affect the bubble dynamics in turn, and further affect the precise control of intensity of cavitation field. This study used high-speed photography technology and schlieren optical path system to observe the spatiotemporal evolution of shockwaves in liquid with different viscosities. It was found that as the viscosity of the liquid increased, the wave front of the collapse shockwave of the cavitation bubble gradually thickened. Furthermore, a high-frequency pressure testing system was used to quantitatively analyze the influence of viscosity on the intensity of the shockwave. It was found that the pressure peak of the shockwave in different viscous liquid was proportional to L^b (L represented the distance between the center of bubble and the sensor measuring point), and the larger the viscosity was, the smaller the value of b was. Through in-depth analysis, it was found that as the viscosity of the liquid increased, the proportion of the shockwave energy of first bubble collapse to the maximal mechanical energy of bubble gradually decreased. The proportion of the mechanical energy of rebounding bubble to the maximal mechanical energy of bubble gradually increased. These new findings have an important theoretical significance for the efficient utilization of ultrasonic cavitation.

The aim of the present study was to evaluate the effects of ultrasound-assisted intermittent tumbling (UT) at 300 W, 20 kHz and 40 min on the conformation, intermolecular interactions and aggregation of myofibrillar proteins (MPs) and its induced gelation properties at various tumbling times (4 and 6 h). Raman results showed that all tumbling treatments led the helical structure of MPs to unfold. In comparison to the single intermittent tumbling treatment (ST), UT treatment exerted more pronounced effects on strengthening the intermolecular hydrogen bonds and facilitating the formation of an ordered β-sheet structure. When the tumbling time was the same, UT treatment caused higher surface hydrophobicity, fluorescence intensity and disulfide bond content in the MPs, inducing the occurrence of hydrophobic interaction and disulfide cross-linking between MPs molecules, thus forming the MPs aggregates. Additionally, results from the solubility, particle size, atomic force microscopy and SDS-PAGE further indicated that, relative to the ST treatment, UT treatment was more potent in promoting the polymerization of myosin heavy chain. The MPs aggregates in the UT group were more uniform than those in the ST group. During the gelation process, the pre-formed MPs aggregates in the UT treatment increased the thermal stability of myosin, rendering it more resistant to heat-induced unfolding of the myosin rod region. Furthermore, they improved the protein tail–tail interaction, resulting in the formation of a well-structured gel network with higher gel strength and cooking yield compared to the ST treatment.