Cavitation Effects Research Articles

Nonlinear friction dynamics of water-lubricated bearings under transient shocks considering cavitation and turbulence effects

This study proposes a transient elastohydrodynamic mixed lubrication (EHML) model for water-lubricated bearings (WLBs) that incorporates cavitation and turbulence effects to evaluate the nonlinear friction dynamic performance under transient shock loads. The generalized average Reynolds equation is discretized using the control volume technique (CVM), and the constrained system is solved using the Fischer-Burmeister-Newton-Schur (FBNS) method. The validity of the model is verified by a comparison of experimental data from published literature. On this basis, the effects of cavitation, turbulence, shock load amplitude, direction, time, and rotational speed on WLB nonlinear friction dynamics characteristics are investigated. The results show that cavitation induces hydrodynamic loss under transient shock conditions, significantly increases contact time and load, and exacerbates the hydrodynamic instability phenomenon. In contrast, the turbulence effect effectively reduces frictional contact. The stability of WLBs under transient shock conditions is closely related to the load offset angle. Reducing the load offset angle improves the anti-shock stability of the bearings. Nevertheless, an increase in the amplitude and duration of the shock load may result in a deterioration of the frictional contact behavior. Increasing the rotational speed appropriately favors accelerating the lubrication regime transition and improving WLB’s anti-shock stability. This study provides a reference for enhancing WLB anti-shock performance and optimizing structural design.

Synthesis and characterization of MWCNTs nanocomposite for fabrication of tensometric transducers

A nanocomposite was prepared using MWCNTs and micro-sized bronze particles dispersed in elastomer silicone organic compound (SILAGER 8030). The nano-composite was characterized by FT-IR, SEM, EDS and Raman spectroscopy; showing the rough surface of the composite with interweaving of nano threads. This nano-composite was used to manufacture strain gauge. The conductivities were measured concerning wt% of micro-sized bronze, compression and time. The maximum electrical conductivity obtained was 2.1 S/m at 5.0 wt% bronze metal alloy and MWCNT (3.0 wt%) at 16% compression. With increasing amplitude and frequency of ultrasonic exposure, an increase in the pressure associated with cavitation in the liquid was observed. Each value of ultrasound exposure corresponded to a certain value of electrical resistance. At the same time, with an increase in the intensity of the cavitation effect on the strain gauge transducer, extremum points appeared, which corresponded to a decrease in resistance. The developed material is highly useful for manufacturing strain gauges to be used in liquid ring vacuum pumps as a measuring transducer of liquid ring pressure into signals associated with changes in resistance. This allows liquid ring vacuum pumps to be precisely controlled; improving their energy efficiency and reliability.

Influence of ultrasonic power modulation on the optimisation of aluminium alloy micro-arc oxidation coating properties

Conventional micro-arc oxidation (MAO) technology, due to the randomness and transient nature of arc discharge, produces coatings with numerous defects, poor abrasion resistance, and inadequate ability to effectively block the intrusion of corrosive media. In this paper, ultrasonic-assisted technology was used to study the effect of different ultrasonic power regulation on the performance optimization of MAO coating on 6061 aluminum alloy. The coating microstructure and elemental composition were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer, and its hardness, wear resistance, corrosion resistance and other properties were tested. The results show that the prepared coating has the characteristics of high hardness, good wear resistance and excellent corrosion resistance under the assistance of ultrasonic power of 50 W. This is mainly attributed to the cavitation effect, mechanical effect and thermal effect generated by the corresponding ultrasonic power, which effectively enhances the surface quality, performance and service life of the coating. This study provides valuable insights into the interaction between ultrasound power and the resulting MAO coatings, and has important implications for optimizing ultrasound-assisted processes and improving coating properties.

Study on high-order-mode oscillation and migration characteristics of single bubble in the ultrasonic field

Abstract Investigating the motion characteristics of cavitation bubbles in an ultrasonic field is important for industries such as ultrasonic cleaning and ultrasonic therapy. This paper investigated the oscillation and migration characteristics of a single cavitation bubble in a 20 kHz ultrasonic field. Peristaltic pump syringe injection tests were performed at different locations in a 20 kHz ultrasonic field, and a high-speed camera was used to observe the bubble motion characteristics. The bubble was found to resonate with the ultrasonic waves at a higher order mode, changing from spherical shape to honeycomb and golf ball shapes. Also, we found that the ultrasonic waves may prevent the buoyancy of the bubble. Through revealing the motion characteristics of the bubble in the ultrasonic field, we may control the bubble motion by ultrasonic, and strengthen the bubble cavitation effect.

Ultrasonic-induced crystallization for efficient extraction of hazardous sodium oxalate with ultra-low alkali loss in alumina industry: From laboratory-scale to continuous pilot-scale

Since sodium oxalate (Na2C2O4) in Bayer liquor seriously threatens the sustainable development of the alumina (Al2O3) industry, efficient extraction of Na2C2O4 and reduction of alkali loss have received widespread attention. A new process for extracting Na2C2O4 from mother aluminate liquor by ultrasonic-induced crystallization (UIC) is established at laboratory scale. Due to the controlled sound field and cavitation effect, compared with conventional crystallization (CC) process, the UIC process increases the Na2C2O4 extraction rate from 61 % to 70 %, and reduces the alkali loss rate from 41 % to 19 %. Numerical simulation and sonochemiluminescence confirm that the cavitation effect is mainly concentrated near the axis and at the tip of the titanium alloy horn, and the average life of the cavitation bubble is maintained at 0.9 ms. Density functional theory (DFT) calculations, crystal structure observations and simulations show that the UIC process successfully promotes the development of Na2C2O4 from long strips to lamellar forms, maintaining the safety of Al2O3 production. Additionally, UIC process operates stably on continuous pilot-scale (CPSC) system, with the Na2C2O4 extraction rate and TOC emission rate remaining at around 50 % and 85 % respectively. The UIC method for extracting Na2C2O4 is expected to generate annual profits of $ 267.3 million for China, while also providing support for the innovation and application of ultra-low alkali loss in Al2O3 industry.

Effect of organic solvent additives on the enhancement of ultrasonic cavitation effects in water for lithium-ion battery electrode delamination

Ultrasonic delamination is a low energy approach for direct recycling of spent lithium-ion batteries. The efficiency of the ultrasonic delamination relies both on the thermophysical properties (such as viscosity, surface tension, and vapour pressure) of the solvent in which the delamination process is carried out, and the properties of the ultrasound source as well as the geometry of the containment vessel. However, the effect of tailoring solutions to optimise cavitation and delamination of battery cathode coatings has not yet been sufficiently investigated. Acoustic detection, high-speed imaging, and sonochemiluminescence (SCL) are employed to study the cavitation processes in water-glycol systems and identify the effect of tailoring solvent composition on cavitation strength. The addition of small volume fractions of organic solvent (ca. 10–30 vol%), including ethylene glycol or glycerol, to the aqueous delamination solution were found to significantly improve the delamination efficiency of lithium-ion battery cathode coatings due to the alteration of these thermophysical properties. However, greater volume fractions of glycol decrease delamination efficiency due to the signal-dampening effect of viscosity on the ultrasonic waves. The findings of this study offer valuable insights for optimising ultrasonic bath solution composition to enhance film delamination processes.

The impact of solid particles and oil characteristics on the separation efficacy of oil sludge ultrasonic treatment

This study assesses the efficiency of ultrasonic treatment on oil sludge, with a specific focus on the impact of particle size and content, crude oil viscosity, and the interactions between crude oil and solid particles. The findings indicated that lower solids content correlates with increased oil recovery. For example, oil recovery rose from 15.09 % to 34.34 % as the solid content changed from 80 % to 40 % (200∼300 mesh). Furthermore, the study underscores the significant role of cavitation, particularly in the aqueous phase, and its dependency on fluid viscosity. Elevated viscosity raises the cavitation threshold of the medium, hindering the occurrence of cavitation effects and weakening the microjet. Acoustic energy attenuation during treatment should be emphasized, and both the propagation medium and the distance have an effect on the acoustic energy, which can be weaken by changing the ultrasonic irradiation method or by adjusting the size of the reaction unit. These findings provide valuable guidance for the ultrasonic treatment of oil sludge for optimizing crude oil recovery.

Research on the influence of unsteady cavitation on the dynamics structures of a twisted hydrofoil based on variational mode decomposition method

Cavitation will produce complex dynamic effects on hydrofoil structures. In this paper, the effects of unsteady cavitation conditions on the dynamics of twisted hydrofoil structures are studied by using variational mode decomposition (VMD) and pearson correlation coefficient (PCC), etc. The research results indicate that there is a certain synergy between the flow field pressure pulsation signal and the structural field stress-strain signal in the frequency distribution of the hydrofoil under cavitation conditions. The second-order center frequency of ΔP1 and the first-order center frequency of ΔP7 are close to the second-order center frequency of the stress-strain signal of the hydrofoil (1202.4Hz). Unsteady cavitation can lead to the increase of the high effective force region of the hydrofoil, especially the high effective force region connecting the leading edge and the root, which is the reason for the degradation of the hydrofoil performance. Cavitation increases the natural frequency of the hydrofoil, but has no obvious effect on the natural mode of the hydrofoil. The research results of this study reveal the effect of unsteady cavitation on the dynamics of hydrofoil structure, and provide important theoretical support for the optimization design and performance improvement of hydrofoil structure.

Enhanced oil recovery in tight reservoirs by ultrasonic-assisted CO2 flooding: Experimental study and molecular dynamics simulation

CO2-enhanced oil recovery (CO2-EOR) has attracted great attention due to its dual effects of geological carbon storage and economic benefits, but the clay swelling, asphaltene deposition and gas channeling induced by CO2 still restrict its field application. The employment of chemical agents for the purpose of improving CO2-EOR performance is often limited by the heterogeneity of reservoirs and the potential for formation damage. Physical methods, such as ultrasonic-assisted CO2 flooding, appear to offer a promising alternative for CO2-EOR and geological sequestration. This study has conducted oil displacement experiments to investigate the EOR potential of ultrasonic-assisted CO2 flooding in tight reservoirs and clarify the effects of different ultrasound parameters. The ultrasonic waves with 20 kHz of acoustic frequency, 30 W/cm2 of sound intensity, 30 min of sonication time and moderate intermittent working mode can yield violent cavitation effects and avoid undesirable energy dissipation. Nearly a quarter of the saturated crude oil can be recovered from the tight core through ultrasonic-assisted CO2 flooding. It can be attributed to the composition alterations of crude oil and property changes of core matrix. Coupling with ultrasonic waves, CO2 would extract and vaporize crude oil more easily, which promotes oil swelling, lowers oil density and viscosity, decreases oil–gas interfacial tension and thus improves oil recovery. Besides, the ultrasound can help to mitigate the impact of CO2 adsorption-induced clay swelling on pore sizes through fluctuating pressure. And the strong hydrodynamic shear forces generated by mechanical vibration of ultrasound may also help to connect individual small pores and extend micro-fractures. These synergistic effects result in the transformation of micropores into mesopores and macropores. Furthermore, the wettability alteration of core samples implies that the ultrasonic-assisted CO2 flooding can induce the detachment of oil films from the rock surface. Finally, the results of molecular dynamics simulations indicate that the improvement in pressure inside the core sample resulting from ultrasonic cavitation facilitates the mixing of CO2 and oil, thereby weakening gas channeling and improving the displacement efficiency.

Combination of contact ultrasound and infrared radiation for improving the quality and flavor of air-dried beef during hot air drying

Air-dried beef, a traditional dry fermented meat product in China, whose quality is largely influenced by processing conditions. In this study, contact ultrasound (CU) and infrared radiation (IR) were employed to enhance hot air drying (HAD), with an investigation into the mechanisms underlying improvements in quality and flavor. Samples subjected to CU and IR treatments during HAD (CU-IRD) demonstrated superior color (L* = 42.68, a* = 5.05, b* = −3.86) and tenderness (140.59 N) than HAD group, primarily attributed to reduced drying times and alterations in ultrastructure. Analyses utilizing SDS-PAGE and total volatile basic nitrogen (TVB-N) revealed that HAD and CU-HAD resulted in significant protein oxidation (197.85 mg TVB-N/kg and 202.23 mg TVB-N/kg, respectively), while IR treatments were associated with increased thermal degradation of proteins, producing lower molecular weight peptides. Compared with HAD group, the activities of certain lipases and proteases were enhanced by ultrasound and infrared treatments, leading to the release of greater amounts of free fatty acids and flavor amino acids. Furthermore, the thermal effects of infrared and the cavitation effects of ultrasound contributed to increased fat oxidation, amino acid Strecker degradation, and esterification reactions, thereby augmenting the diversity and concentration of volatile flavor compounds, including alkanes, ketones, aldehydes, and esters. These findings indicate that the synergistic application of CU and IR represents a promising strategy for enhancing the quality of air-dried beef.

Improving efficiency of road transport through the use of hydrodiodes in hydraulic systems taking into account cavitation phenomena

Introduction. One of the promising ways to reduce dynamic loads during operation of hydraulic crane manipulator installations is the use of hydrodiodes. In hydraulic systems operating at high speeds of the working fluid, cavitation phenomena may occur in the hydrodiode, which are accompanied by increased noise and vibration, and may lead to the destruction of the hydrodiode, which is not acceptable. The paper compares the results of calculating the flow of liquid in the flow part of a vortex hydrodiode, taking into account cavitation phenomena and without cavitation phenomena, with the results of research tests. The analysis of the effect of cavitation on the working processes in a vortex hydrodiode for crane manipulator installations is presented.Materials and method. Computational fluid dynamics (CFD) models using the FLUENT CFD code to study the working processes occurring in the working chamber of a vortex hydrodiode were developed. The commercial CFD code ANSYS FLUENT to simulate the flow of liquid in the flow part of a vortex hydrodiode was used.Results. The paper verifies the results of a numerical experiment with the results of research tests. A quantitative and qualitative analysis of the effect of cavitation on the working processes of a vortex hydrodiode has been carried out.Discussion and conclusion. It has been found that the values of pressure and diode in calculations taking into account cavitation and without cavitation practically do not differ, thus, the effect of cavitation at Reynolds numbers Re<30000 does not significantly affect the quantitative values of the parameters of the vortex hydrodiode and the cavitation calculation module can not be used. However, at higher values of the Reynolds numbers, cavitation appears in the working cavity of the vortex hydrodiode and the calculated values of the parameters of the hydrodiode without cavitation and taking cavitation into account differ significantly. Therefore, when calculating high-speed flows, it is necessary to use the cavitation calculation module. The analysis of the effect of cavitation on the working processes of a vortex hydrodiode showed that in the forward direction of the flow, cavitation does not significantly affect the parameters of the hydrodiode and the place of its formation, the upper inlet region of th tangential chamber. In the opposite direction of flow, cavitation has a significant effect on the pattern of fluid flow in the vortex hydrodiode. Cavitation covers almost the entire inlet volume of the radial tube and partially captures the central part of the vortex chamber

Research on a harmless treatment method for oily sludge in coal chemical wastewater and the pollutant transformation mechanism of oily sludge during the treatment process

This study developed an ultrasound synergistic subcritical hydrothermal treatment method (U-SHT) to address the challenges posed by the high oil and water content, complex composition, and hazardous nature of oily sludge (OS) generated during the pretreatment of coal chemical wastewater. The study investigated the efficiency of this method for the harmless disposal and resource recovery of OS, and the migration-transformation mechanism of hazardous organic pollutants in OS. The findings revealed that U-SHT achieved a removal efficiency of chemical oxygen demand in OS of 91.16 %, an oil resource recovery efficiency of 96.60 %, and a residual oil rate of 0.28 %, meeting API emission standards. Further research indicated that the solubilizing effect of the surfactant on the oil enhanced the demulsifying effect of ultrasonic cavitation on the emulsified structure of OS, enabling ultrasound to efficiently release and disperse pollutants within OS. This promoted the decomposition and transformation of pollutants under subcritical hydrothermal conditions, with synergistic removal efficiencies for typical pollutants such as long-chain alkanes, polycyclic aromatic hydrocarbons, and phenols reaching 96.61 %, 97.63 %, and 97.76 %, respectively. Economic evaluation indicated that the cost of OS treatment was $29.66/m3, significantly lower than existing methods, demonstrating promising practical application prospects.

Effect of Low-Temperature Argon Plasma and Ultrasonic Cavitation on the Course of Burn Wound Healing

Background: Various physical phenomena come into use in medicine; however, to date, universal physical methods have not been developed to optimize the course of the wound healing at all treatment stages. In combustiology, the first stage of burn treatment is debridement; then it is important to create an optimal biological environment, normalize blood circulation, suppress pathogenic flora, and stimulate proliferative processes in the wound.Objective: To determine the effectiveness of low-temperature argon plasma (LTAP) and ultrasonic cavitation in deep burn wound treatment based on clinical observations and cytological findings.Materials and methods: We studied impression smears from burn wounds of 36 patients with deep burns of various etiologies who were treated using LTAP and ultrasonic cavitation in the Thermal Injuries Unit at the Saint Petersburg I.I. Dzhanelidze Research Institute of Emergency Medicine (Saint Petersburg, Russian Federation) between 2022 and 2023.Results: We found that cytogram findings in the study area changed from the inflammatory type to the regenerative-inflammatory one on day 3-7 when LTAP and ultrasonic cavitation were used, while such change in the control area was observed only after 10 days of treatment. Thanks to the use of LTAP and ultrasound after necrosectomy for deep dermal burns, the wound preparation for autologous skin grafting takes less time than it does with standard methods of local burn wound care. Ultrasonic cavitation should be used in cases of severe exudation and slough, whereas LTAP should be used when reparative processes in a burn wound slow down.Conclusions: Burn wound treatment using ultrasonic cavitation and LTAP enables to prepare the wound surface for autologous skin grafting with a high engraftment rate. The procedure allows to effectively and atraumatically debride the wound and suppress pathogenic microflora. Further research is planned in patients with large deep burn wounds.

Effects of ultrasonic waves of different powers on the physicochemical properties, functional characteristics, and ultrastructure of bovine liver peptides

In recent years, ultrasound has emerged as a widely used technology for modifying proteins/peptides. In this study, we focused on the intrinsic mechanism of ultrasound-induced modification of bovine liver peptides, which were treated with ultrasound power of 0, 100, 200, 300, 400, and 500 W, and their physicochemical and functional properties, as well as ultrastructures, were investigated. The results show that ultrasound mainly affects hydrogen bonding and hydrophobic interactions to change the conformation of proteins and unfolds proteins through a cavitation effect, leading to an increase in biological activity. Fourier infrared spectroscopy showed that ultrasound inhibited the formation of hydrogen bonds and reduced intermolecular cross-linking. Molecular weight distribution showed that the antioxidant components of bovine liver polypeptides were mainly concentrated in fractions of 500–1,000 Da. Maximum values of ABTS (82.66 %), DPPH (76.02 %), chelated iron (62.18 %), and reducing power (1.2447) were obtained by treating bovine liver polypeptides with 500 W ultrasound. Combined with the scanning electron microscopy results, with the intervention of ultrasound, the impact force generated by ultrasonication may lead to the loosening of the protein structure, which further promotes the release of antioxidant peptides, and these findings provide new insights into the application of ultrasound in the release of antioxidant peptides from bovine liver.

Study on ultrasound-enhanced molecular transport in articular cartilage.

Local intra-articular administration with minimal side effects and rapid efficacy is a promising strategy for treating osteoarthritis(OA). Most drugs are rapidly cleared from the joint space by capillaries and lymphatic vessels before free diffusion into cartilage. Ultrasound, as a non-invasive therapy, enhances molecular transport within cartilage through the mechanisms of microbubble cavitation and thermal effects. This study investigated the mass transfer behavior of solute molecules with different molecular weights (479 Da, 40 kDa, 150 kDa) within porcine articular cartilage under low-frequency ultrasound conditions of 40 kHz and ultrasound intensities of 0.189 W/cm2 and 0.359 W/cm2. The results revealed that under the conditions of 0.189 W/cm2 ultrasound intensity, the mass transfer concentration of solute molecules were higher compared to passive diffusion, and with an increase in ultrasound intensity to 0.359 W/cm2, the mass transfer effect within the cartilage was further enhanced. Ultrasound promotes molecular transport in different layers of cartilage. Under static conditions, after 2 h of mass transfer, the concentration of small molecules in the superficial layer is lower than that in the middle layer. After applying ultrasound at 0.189 W/cm2, the molecular concentration in the superficial layer significantly increases. Under conditions of 0.359 W/cm2, after 12 h of mass transfer, the concentration of medium and large molecules in the deep layer region increased by more than two times. In addition, this study conducted an assessment of damage to porcine articular cartilage under ultrasound exposure, revealing the significant potential of low-frequency, low-intensity ultrasound in drug delivery and treatment of OA.

Recent Advances in Basic Studies of Low-Intensity Pulsed Ultrasound in Periodontal Tissue Regeneration: A Systematic Review.

Approximately half of the adult population is suffering from periodontal disease, and conventional periodontal treatment strategies can only slow the progression of the disease. As a kind of tissue engineering, periodontal regeneration brings hope for the treatment of periodontal disease. Low-intensity pulsed ultrasound (LIPUS) is a form of ultrasound with a frequency of 1-3MHz and a much lower intensity (< 1W/cm2) than traditional ultrasound energy and output. LIPUS has been adopted for a variety of therapeutic purposes due to its bioeffects such as thermal, mechanical, and cavitation effects, which induce intracellular biochemical effects and lead to tissue repair and regeneration ultimately. In this systematic review, we summarize the basic research of LIPUS in the treatment of periodontal disease in periodontal disease animal models and the influence of LIPUS on the biological behavior (including promoting osteogenic differentiation of stem cells and inhibiting inflammatory response) and potential mechanism of periodontal ligament stem cells (PDLSCs), hoping to provide new ideas for the treatment of periodontal disease. We believe that LIPUS can be used as an auxiliary strategy in the treatment of periodontal disease and play an exciting and positive role in periodontal regeneration.

Sea Bass Fish Head Broth Treated by Thermo-Ultrasonication: Improving the Nutritional Properties and Emulsion Stability.

This work investigated the underlying mechanism of thermo-ultrasonic treatment to improve the nutritional properties and emulsion stability of sea bass fish head broth. The effects of ultrasonication on the processing of fish broth were compared with boiling water treatment. The nutritional properties of fish broth mainly include protein, fat, total sugar, 5'-nucleotide and free amino acid content. To achieve a similar effect of nutrient extraction, the thermo-ultrasonic treatment required a shorter time (30 min) than boiling water (120 min). The water-soluble protein, fat and total sugar contents were at their maximum at 120 min of the thermo-ultrasonic treatment. In particular, the fat content increased with the time of thermo-ultrasonic treatment from 0.58% to 2.70%. The emulsion structure of the fish soup was characterized by measuring its color and particle size, using optical microscopy and confocal laser scanning microscopy, and determining its storage stability. Thermo-ultrasonic treatment reduced the particle size of the fish broth emulsion and the fat globules became smaller and more homogeneous. Ultrasonication not only accelerated the nutritional and flavor content of the fish head broth, but also reduced the particle size and enhanced the stability of the emulsified system of the fish broth. The fish head tissue was more severely disrupted by the cavitation effect of an ultrasound, and nutrients migrated more and faster. This was mainly due to the cavitation and mechanical breaking force of the ultrasound on the fish head tissue and the fat globules of the fish broth. Altogether, these findings suggest that the thermo-ultrasonic treatment technique is useful for processing nutrient-rich, storage-stable and ready-to-eat fish head broth.

High-speed synchrotron X-ray imaging of melt pool dynamics during ultrasonic melt processing of Al6061

Ultrasonic processing of solidifying metals in additive manufacturing can provide grain refinement and advantageous mechanical properties. However, the specific physical mechanisms of microstructural refinement relevant to laser-based additive manufacturing have not been directly observed because of sub-millimeter length scales and rapid solidification rates associated with melt pools. Here, high-speed synchrotron X-ray imaging is used to observe the effect of ultrasonic vibration directly on melt pool dynamics and solidification of Al6061 alloy. The high temporal and spatial resolution enabled direct observation of cavitation effects driven by a 20.2 kHz ultrasonic source. We utilized multiphysics simulations to validate the postulated connection between ultrasonic treatment and solidification. The X-ray results show a decrease in melt pool and keyhole depth fluctuations during melting and promotion of pore migration toward the melt pool surface with applied sonication. Additionally, the simulation results reveal increased localized melt pool flow velocity, cooling rates, and thermal gradients with applied sonication. This work shows how ultrasonic treatment can impact melt pools and its potential for improving part quality.

Enhanced La(III) adsorption performance and mechanism of urea-modified dolomite composite adsorbent

Dolomite, a prevalent mineral in rock formations, often coexists with various minerals, impacting their properties and typically being discarded as waste in the extraction process of other minerals. This research introduces a straightforward and effective technique for co-calcining urea with natural dolomite at 550℃, yielding a novel composite adsorbent designated as CN/xDO, where ‘x’ denotes the proportion of dolomite incorporated. During the preparation, urea promotes the conversion of dolomite to nano calcite, and the gas produced by urea pyrolysis during the calcination process has a cavitation effect on the material, enhancing its surface properties. BET analysis reveals that the specific surface area and total pore volume of CN/xDO notably surpass those of pure dolomite, with CN/0.6DO achieving 2.9479 m2/g and 0.0382 cm3/g, respectively. CN/0.6DO demonstrates an adsorption capacity of 237.91 mg/g for La(III) within 360 min at 298 K, which is 16.9 times greater than that of untreated dolomite (14.05 mg/g). The maximum adsorption capacity of CN/0.6DO for La(III) (C0 = 500 mg/L) reaches 382.94 mg/g at 308 K, exceeding the majority of adsorbents documented in the literature. The comparative analysis of batch adsorption experiments and material characterization before and after the adsorption process reveals that the mechanisms adsorption of La(III) adsorption by CN/xDO include physical adsorption, cation-π interactions, ion exchange, and complexation with oxygen-containing functional groups, especially −OH, CO32-. This study broadens the application of dolomite in adsorption and introduces a new strategy for the efficient recovery of rare earth elements from wastewater, consistent with the principles of sustainable development.

Effects of cavitation and erosion on submersible drainage pumps: A numerical study

Submersible drainage pumps are used around the world both residentially and industrially for draining water and sewage. However, these pumps are prone to wear and clogging when the flows inward contain particles and air bubbles, and the combined effects of cavitation and erosion directly affect the performance of such pumps and degrade their efficiency. Therefore, it is essential to design a submersible pump that mitigates the adverse effects of cavitation and erosion. Reported here is an energy-efficient submersible drainage pump for use in emergency response. The combined cavitation–erosion effects are established in order to reduce their adverse impact on the pump, and how erosion wear affects the cavitation characteristics of the water in the pump is investigated. An experiment was conducted to verify the numerical results pump, and then, the influences of particle concentration and size on two-stage existing and altered model submersible pumps were analyzed using computational fluid dynamics. The results show that the performance of the altered model pump increased by 4.34%, with the cavitation–erosion effects reduced significantly. In addition, higher particle concentration induced higher erosion rates at both the leading and trailing edges of the impeller blades. Furthermore, the altered model significantly reduced the cavitation–erosion impact on the pump impeller blades compared to the existing model.