Gold ores in the Jiaozhou region of China are characterized by their abundant reserves,low grade,fine dissemination,and chal-lenges in upgrading.Froth flotation,with xanthate as the collector,is a commonly employed me...Gold ores in the Jiaozhou region of China are characterized by their abundant reserves,low grade,fine dissemination,and chal-lenges in upgrading.Froth flotation,with xanthate as the collector,is a commonly employed method for enriching auriferous pyrite from these ores.This study aimed to develop a more efficient flotation process by utilizing cavitation nanobubbles for a low-grade gold ore.Batch flotation tests demonstrated that nanobubbles significantly enhanced the flotation performance of auriferous pyrite,as evidenced by improved concentrate S and Au grades and their recoveries.The mechanisms underlying this enhancement were explored by investigat-ing surface nanobubble(SNB)formation,bulk nanobubble(BNB)attachment to hydrophobic pyrite surfaces,and nanobubble-induced agglomeration using atomic force microscopy(AFM)and focused beam reflectance measurement(FBRM).The results revealed that nan-obubble coverage on the pyrite surface is a critical factor influencing surface hydrophobicity and agglomeration.SNBs exhibited higher coverage on pyrite surfaces with increased surface hydrophobicity,flow rate,and cavitation time.Similarly,BNB attachment on pyrite surfaces was significantly increased with surface hydrophobicity and cavitation time.Enhanced surface hydrophobicity,along with higher flow rates and cavitation times,promoted pyrite particle agglomeration owing to the increased nanobubble coverage,ultimately leading to improved flotation performance.展开更多
To investigate the mechanisms of how nanobubbles enhance the flotation separation performance of galena from pyrite,the effects of nanobubbles on the surface properties of galena and pyrite and the interactions betwee...To investigate the mechanisms of how nanobubbles enhance the flotation separation performance of galena from pyrite,the effects of nanobubbles on the surface properties of galena and pyrite and the interactions between mineral particles and air bubbles were examined in this study.Various analytical techniques,including focused beam reflectance measurement(FBRM),three-phase contact line(TPCL)analysis,atomic force microscopy(AFM),and contact angle measurement,were employed.It has been demonstrated that nanobubbles significantly enhanced the flotation recovery of galena and its flotation selectivity from pyrite,as compared to the conventional flotation process.The preferential formation of nanobubbles on the galena surface,which is more hydrophobic than pyrite surface,further increased the surface hydrophobicity and agglomeration of galena particles.The introduction of nanobubbles into the flotation system also increased in the maximum TPCL length and detachment length between the galena surface and bubbles,contributing to the enhanced flotation efficiency.展开更多
The stable nanobubbles adhered to mineral surfaces may facilitate their efficient separation via flotation in the mining industry.However,the state of nanobubbles on mineral solid surfaces is still elusive.In this stu...The stable nanobubbles adhered to mineral surfaces may facilitate their efficient separation via flotation in the mining industry.However,the state of nanobubbles on mineral solid surfaces is still elusive.In this study,molecular dynamics(MD)simulations are employed to examine mineral-like model surfaces with varying degrees of hydrophobicity,modulated by surface charges,to elucidate the adsorption behavior of nanobubbles at the interface.Our findings not only contribute to the fundamental understanding of nanobubbles but also have potential applications in the mining industry.We observed that as the surface charge increases,the contact angle of the nanobubbles increases accordingly with shape transformation from a pancake-like gas film to a cap-like shape,and ultimately forming a stable nanobubble upon an ordered water monolayer.When the solid–water interactions are weak with a small partial charge,the hydrophobic gas(N_(2))molecules accumulate near the solid surfaces.However,we have found,for the first time,that gas molecules assemble a nanobubble on the water monolayer adjacent to the solid surfaces with large partial charges.Such phenomena are attributed to the formation of a hydrophobic water monolayer with a hydrogen bond network structure near the surface.展开更多
We study the effects of gas adsorption on the dynamics and stability of nanobubbles at the solid–liquid interface. The phase diagram and dynamic evolution of surface nanobubbles were analyzed under varying equilibriu...We study the effects of gas adsorption on the dynamics and stability of nanobubbles at the solid–liquid interface. The phase diagram and dynamic evolution of surface nanobubbles were analyzed under varying equilibrium adsorption constant.Four distinct dynamic behaviors appear in the phase diagram: shrinking to dissolution, expanding to bursting, shrinking to stability, and expanding to stability. Special boundary states are identified in phase diagram, where the continuous growth of nanobubbles can take place even under very weak gas–surface interaction or with very small initial bubble size. Surface adsorption plays a critical role in the stability, lifetime, radius, and contact angle of nanobubbles, thereby demonstrating that pinning is not a prerequisite for stabilization. Furthermore, stable equilibrium nanobubbles exhibit a characteristic range of footprint radius, a limited height, and a small contact angle, consistent with experimental observations.展开更多
Taking advantage of the extremely small size of the gold nanodisk electrode,the single hydrogen nanobubble generated on the surface of the nanoelectrode was studied to evaluate its hydrogen evolution performance.It wa...Taking advantage of the extremely small size of the gold nanodisk electrode,the single hydrogen nanobubble generated on the surface of the nanoelectrode was studied to evaluate its hydrogen evolution performance.It was found that compared with the bare gold nanodisk electrode,the bubble formation potential of the gold nanodisk electrode modified with tungsten disulfide quantum dots(WS_(2)QDs)on the surface was more positive,indicating that its hydrogen evolution activity was higher.Microdynamic model analysis shows that the average standard rate constant of the rate-determining step of the hydrogen evolution reaction of gold nanoelectrodes modified with WS_(2)QDs is approximately 12 times larger than that of gold nanoelectrodes.This work based on the formation of nanobubbles provides new ideas for the design and performance evaluation of hydrogen evolution reaction catalysts.展开更多
The anoxia of coastal water has already been a serious problem all over the word.Nanobubbles are proved to have great applications in water remediation because they could effectively increase the oxygen content and de...The anoxia of coastal water has already been a serious problem all over the word.Nanobubbles are proved to have great applications in water remediation because they could effectively increase the oxygen content and degrade organic matters in water.But the existing methods to produce nanobubbles are complicated and high cost to operate,especially in deep sea.In this paper,we presented a low-cost method,hydraulic air compression(HAC),to produce a large number of nanobubbles and proved that nanoscale gas bubbles could be produced by HAC for the first time.Nanoparticle tracking analysis was used to measure the size and concentration of produced nanobubbles.It indicated that the concentration of nanobubbles would increase as the downpipe height increases.Degassed measurements proved that produced“nanoparticles”are gas nanobubbles indeed.More dissolved oxygen in water would provide the source for larger number of nanobubble formation.Those results are expected to be very helpful for water remediation in ocean in the future.展开更多
A special nanobubble generation system has been developed for evaluating the effect of nanobubble on froth flotation. In this study, an eight-factor five-level Central Composite Experimental Design was conducted for i...A special nanobubble generation system has been developed for evaluating the effect of nanobubble on froth flotation. In this study, an eight-factor five-level Central Composite Experimental Design was conducted for investigating eight important parameters governing the median size and the volume of nanobubbles. These process parameters included surfactant concentration, dissolved oxygen (O2) content, dissolved carbon dioxide gas (CO2) content, pressure drop in cavitation tube nozzle, <50 nm hydrophobic particle concentration, <50 nm hydrophilic particle concentration, slurry temperature and the time interval after nanobubble generation. The properties, stability and uniformity of nanobubbles were investigated. The study of the produced nanobubble’s effects on the characteristics of microbubble solutions and millimeter scale bubble solutions was performed in a 50.8 mm column.展开更多
Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing pla...Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing plants to reduce milling cost and increase valuable mineral recovery. Based on this, the effects of nanobubbles(NBs) and hydrodynamic parameters on coarse quartz particle flotation were systematically investigated. Mechanical flotation experiments were carried out using the 7 cm and 9 cm diameter impellers in order to produce different hydrodynamic conditions. 900–1300 rpm impeller speeds were used for the 7 cm diameter impeller and 554–786 rpm for the 9 cm diameter impeller. The results show that the presence of NBs increased the flotation recovery of à425 + 106 lm quartz by up to 21%. For the7 cm diameter impeller, the maximum flotation recoveries of 86.4% and 98% were obtained in the absence and presence of NBs at Reynolds number(Re) of 81,000 and 66,000, respectively. For the 9 cm diameter impeller, the maximum recoveries of 86.3% and 97.5% were obtained in the absence and presence of NBs at Re of 90,000 and 75,000, respectively. NBs increased the flotation rate constant up to 36%.展开更多
Froth flotation is a commonly employed technology to improve the quality of raw coal and minerals.Coal and minerals particle size and surface hydrophobicity are two main parameters that affect three key steps in froth...Froth flotation is a commonly employed technology to improve the quality of raw coal and minerals.Coal and minerals particle size and surface hydrophobicity are two main parameters that affect three key steps in froth flotation process:particle-bubble collision,adhesion,and detachment.This paper fundamentally investigated the effects of nanobubble on coal and phosphate flotation.It has been found that the presence of nanobubble in flotation pulp could widen the coal and phosphate flotation particle size range,increase the particle surface hydrophobicity,and thus improve the coal and phosphate froth flotation recovery.展开更多
Nanobubble flotation technology is an important research topic in the field of fine mineral particle separation.The basic characteristics of nanobubbles,including their size,concentration,surface zeta potential,and st...Nanobubble flotation technology is an important research topic in the field of fine mineral particle separation.The basic characteristics of nanobubbles,including their size,concentration,surface zeta potential,and stability have a significant impact on the nanobubble flotation performance.In this paper,bulk nanobubbles generated based on the principle of hydrodynamic cavitation were investigated to determine the effects of different parameters(e.g.,surfactant(frother)dosage,air flow,air pressure,liquid flow rate,and solution pH value)on their size distribution and zeta potential,as measured using a nanoparticle analyzer.The results demonstrated that the nanobubble size decreased with increasing pH value,surfactant concentration,and cavitation-tube liquid flow rate but increased with increasing air pressure and increasing air flow rate.The magnitude of the negative surface charge of the nanobubbles was positively correlated with the pH value,and a certain relationship was observed between the zeta potential of the nanobubbles and their size.The structural parameters of the cavitation tube also strongly affected the characteristics of the nanobubbles.The results of this study offer certain guidance for optimizing the nanobubble flotation technology.展开更多
Physical upgrading of graphite is typically achieved with many stages of grinding and flotation to produce a concentrate with approximately 95% carbon grade.An innovative grinding and column flotation process has been...Physical upgrading of graphite is typically achieved with many stages of grinding and flotation to produce a concentrate with approximately 95% carbon grade.An innovative grinding and column flotation process has been developed for efficient graphite upgrading to substantially simplify the process flowsheet and reduce operating costs.In this process,a high-pressure grinding roller(HPGR) and a stirred mill were employed as primary comminution techniques and a nanobubble flotation column as a key separation process.The results obtained with a crystalline flake graphite sample with a carbon grade of 11.15% show that the novel process can produce a concentrate with 94.82% carbon grade and 97.89% recovery from an open circuit of one rougher and two cleaner flotation stages.Scanning electron microscope(SEM)microphotographs indicate that HPGR offers the advantage of more effective protection of graphite flakes during crushing.Grinding test results show that stirred mill could not only protect graphite flakes but also promote the efficient liberation of graphite.Compared with the traditional flotation process,nanobubble flotation can effectively recover ultrafine graphite.The new process possesses a number of important advantages over the traditional method,including substantially higher graphite recovery,greatly simplified process flowsheet,better protection of flake size,reduced reagent consumption and process costs,etc.展开更多
Froth flotation is used widely for upgrading raw phosphate.The flotation recovery of coarse phosphate(-1.18+0.425 mm) is much lower than that achieved on the-0.425+0.15 mm size fraction.Enhanced recovery of coarse pho...Froth flotation is used widely for upgrading raw phosphate.The flotation recovery of coarse phosphate(-1.18+0.425 mm) is much lower than that achieved on the-0.425+0.15 mm size fraction.Enhanced recovery of coarse phosphate particles is of great economic and environmental importance for phosphate industry.In this investigation,four different phosphate samples were aquired,characterized and tested in a specially designed laboratory-scale flotation column.Significant recovery improvement of coarse phosphate flotation was achieved using cavitation-generated nanobubble though its effects differ among the four testing phosphate samples.The laboratory-scale flotation column test results indicate that nanobubble increased P_2O_5 recovery by up to 10%～30%for a given Acid Insoluble(A.I.) rejection,depending on the characteristic of phosphate samples.The improvement effect of nanobubble on the hard-to-float particles was more significant than that on easy-to-float particles,especially at lower collector dosages.Nanobubbles reduced the collector dosage by 1/3 to 1/2.Nanobubbles almost doubled the coarse phosphate flotation rate constant and increased the flotation selectivity index by up to 25%.展开更多
Coal is the world's most abundant fossil fuel.Coal froth flotation is a widely used cleaning process to separate coal from mineral impurities.Flotation of coarse coal particles,ultrafine coal particles and oxidize...Coal is the world's most abundant fossil fuel.Coal froth flotation is a widely used cleaning process to separate coal from mineral impurities.Flotation of coarse coal particles,ultrafine coal particles and oxidized coal particles is well known to be difficult and complex.In this paper,the nanobubbles' effects on the flotation of the varying particle size,particle density and floatability coal samples were evaluated using a bank of pilot scale flotation cells,a laboratory scale and a pilot scale specially designed flotation column.The parameters evaluated during this study include the flow rate ratio between the nanobubble generator and the conventional size bubble generator,the superficial air velocity,collector dosage,frother concentration,flotation feed rate,feed solids concentration,feed particle size,and the superficial wash water flow rate,etc.The results show that the use of nanobubbles in a bank of mechanical cells flotation and column flotation increased the flotation recovery by 8%～27% at a given product grade.Nanobubbles increased the flotation rate constants of 600～355,355～180,180～75,and 75～0 microns size coal particles by 98.0%,98.4%,50.0% and 41.6%,respectively.The separation selectivity index was increased by up to 34%,depending on the flotation feed characteristics and the flotation conditions.展开更多
Froth flotation is often used for fine-particle separation,but its process efficiency rapidly decreases with decreasing particle size.The efficient separation of ultrafine particles(UFPs)has been a major challenge in ...Froth flotation is often used for fine-particle separation,but its process efficiency rapidly decreases with decreasing particle size.The efficient separation of ultrafine particles(UFPs)has been a major challenge in the mineral processing field for many years.In recent years,the use of surface nanobubbles in the flotation process has been recognized as an effective approach for enhancing the recovery of UFPs.Compared with traditional macrobubbles,nanobubbles possess unique surface and bulk characteristics,and their effects on the UFP flotation behavior have been a topic of intensive research.This review article is focused on the studies on various unique characteristics of nanobubbles and their mechanisms of enhancing the UFP flotation.The purpose of this article is to summarize the major achievements on the two topics and pinpoint future research needs for a better understanding of the fundamentals of surface nanobubble flotation and developing more feasible and efficient processes for fine and UFPs.展开更多
Although various and unique properties of bulk nanobubbles have drawn researchers'attention over the last few years,their formation and stabilization mechanism has remained unsolved.In this paper,we use ultrasonic...Although various and unique properties of bulk nanobubbles have drawn researchers'attention over the last few years,their formation and stabilization mechanism has remained unsolved.In this paper,we use ultrasonic methods to produce bulk nanobubbles in the pure water and give a comprehensive study on the bulk nanobubbles properties and generation.The ultrasonic wave gives rise to constant oscillation in water where positive and negative pressure appears alternately.With the induced cavitation and presence of dissolved air,the bulk nanobubbles formed."Nanosight"(which is a special instrument that combines dynamic light scattering with nanoparticle tracking analysis)was used to analyze the track and concentration of nanobubbles.Our results show that in our experiment,sufficient bulk nanobubbles were generated and we have proven they are not contaminations.We also found nanobubbles in the ultrasonic water change in both size and concentration with ultrasonic time.展开更多
In theory,nanobubbles can stably exist with a lifetime of microseconds at most,but numerous experimental observations demonstrate that nanobubbles in bulk solution can be stable from hours to weeks.Although various co...In theory,nanobubbles can stably exist with a lifetime of microseconds at most,but numerous experimental observations demonstrate that nanobubbles in bulk solution can be stable from hours to weeks.Although various conjectures on the stability mechanism of bulk nanobubbles,such as the contaminant mechanism,skin mechanism,surface zeta potential mechanism,are proposed,there has not yet been a unified conclusion.Since bulk nanobubbles show great potential in a wide spectrum of applications and are relevant to a number of unsolved questions on cavitation and nucleation,the debate over their stability mechanisms has been active.In the past,extensive studies have been carried out to understand the mechanism of nanobubble stability,and important insights have already been provided.This paper will provide a brief overview of our current understanding of the unexpected stability of bulk nanobubbles.展开更多
The great implication of nanobubbles at a solid/water interface has drawn wide attention of the scientific community and industries. However, the fundamental properties of nanobubbles remain unknown as yet. In this pa...The great implication of nanobubbles at a solid/water interface has drawn wide attention of the scientific community and industries. However, the fundamental properties of nanobubbles remain unknown as yet. In this paper, the temperature effects on the morphology of nanobubbles at the mica/water interface are explored through the combination of AFM direct image with the temperature control. The results demonstrate that the apparent height of nanobubbles in AFM images is kept almost constant with the increase of temperature, whilst the lateral size of nanobubbles changes significantly. As the temperature increases from 28℃ to 42℃, the lateral size of nanobubbles increases, reaching a maximum at about 37℃, and then decreases at a higher temperature. The possible explanation for the size change of nanobubbles with temperature is suggested.展开更多
Adhesion is an important process of particle-bubble interaction in fine particle(-10μm)flotation.This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a hig...Adhesion is an important process of particle-bubble interaction in fine particle(-10μm)flotation.This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera,atomic force microscope(AFM),adsorption capacity tests,and induction time tests.After being pretreated with nanobubbles(NBs)water,fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid(CHA)as a collector.The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage.The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration.The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals.Since NBs played a part of the role of collector,it can improve the flotation effect while reducing the amount of collector.The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles.On the other hand,NBs agglomerate cassiterite particles,increasing the probability of particles colliding with bubbles.展开更多
Interfacial gaseous nanobubbles which have remarkable properties such as unexpectedly long lifetime and significant potential applications, are drawing more and more attention. However, the recent dispute about the co...Interfacial gaseous nanobubbles which have remarkable properties such as unexpectedly long lifetime and significant potential applications, are drawing more and more attention. However, the recent dispute about the contamination or gas inside the nanobubbles causes a large confusion due to the lack of simple and clean method to produce gas nanobubbles. Here we report a convenient and clean method to effectively produce interfacial nanobubbles based on a pure water system. By adding the cold water cooled at 4 ℃ for more than 48 h onto highly oriented pyrolytic graphite （HOPG） surface, we find that the average density and total volume of nanobubbles are increased to a high level and mainly dominated by the concentrations of the dissolved gases in cold water. Our findings and methods are crucial and helpful for settling the newly arisen debates on gas nanobubbles.展开更多
Efficient and safe cell engineering by transfection of nucleic acids remains one of the long-standing hurdles for fundamental biomedical research and many new therapeutic applications,such as CAR T cell-based therapie...Efficient and safe cell engineering by transfection of nucleic acids remains one of the long-standing hurdles for fundamental biomedical research and many new therapeutic applications,such as CAR T cell-based therapies.mRNA has recently gained increasing attention as a more safe and versatile alternative tool over viral-or DNA transposon-based approaches for the generation of adoptive T cells.However,limitations associated with existing nonviral mRNA delivery approaches hamper progress on genetic engineering of these hard-to-transfect immune cells.In this study,we demonstrate that gold nanoparticle-mediated vapor nanobubble(VNB)photoporation is a promising upcoming physical transfection method capable of delivering mRNA in both adherent and suspension cells.Initial transfection experiments on HeLa cells showed the importance of transfection buffer and cargo concentration,while the technology was furthermore shown to be effective for mRNA delivery in Jurkat T cells with transfection efficiencies up to 45%.Importantly,compared to electroporation,which is the reference technology for nonviral transfection of T cells,a fivefold increase in the number of transfected viable Jurkat T cells was observed.Altogether,our results point toward the use of VNB photoporation as a more gentle and efficient technology for intracellular mRNA delivery in adherent and suspension cells,with promising potential for the future engineering of cells in therapeutic and fundamental research applications.展开更多
基金support from the National Natural Science Foundation of China(No.52204274)the Shandong Provincial Natural Science Foundation,China(No.ZR2021QE122)+1 种基金Shandong Provincial Department of Science and Technology Key Project,China(No.2023TZXD021)Shandong Provincial Department of Science and Technology,China(No.ZTYJY-KY-2033-11).
文摘Gold ores in the Jiaozhou region of China are characterized by their abundant reserves,low grade,fine dissemination,and chal-lenges in upgrading.Froth flotation,with xanthate as the collector,is a commonly employed method for enriching auriferous pyrite from these ores.This study aimed to develop a more efficient flotation process by utilizing cavitation nanobubbles for a low-grade gold ore.Batch flotation tests demonstrated that nanobubbles significantly enhanced the flotation performance of auriferous pyrite,as evidenced by improved concentrate S and Au grades and their recoveries.The mechanisms underlying this enhancement were explored by investigat-ing surface nanobubble(SNB)formation,bulk nanobubble(BNB)attachment to hydrophobic pyrite surfaces,and nanobubble-induced agglomeration using atomic force microscopy(AFM)and focused beam reflectance measurement(FBRM).The results revealed that nan-obubble coverage on the pyrite surface is a critical factor influencing surface hydrophobicity and agglomeration.SNBs exhibited higher coverage on pyrite surfaces with increased surface hydrophobicity,flow rate,and cavitation time.Similarly,BNB attachment on pyrite surfaces was significantly increased with surface hydrophobicity and cavitation time.Enhanced surface hydrophobicity,along with higher flow rates and cavitation times,promoted pyrite particle agglomeration owing to the increased nanobubble coverage,ultimately leading to improved flotation performance.
基金financial support from the Major Science and Technology Special Project of Yunnan Province,China(No.202302AB080012)the National Natural Science Foundation of China(No.52204274)the Shandong Provincial Natural Science Foundation,China(No.ZR2021QE122).
文摘To investigate the mechanisms of how nanobubbles enhance the flotation separation performance of galena from pyrite,the effects of nanobubbles on the surface properties of galena and pyrite and the interactions between mineral particles and air bubbles were examined in this study.Various analytical techniques,including focused beam reflectance measurement(FBRM),three-phase contact line(TPCL)analysis,atomic force microscopy(AFM),and contact angle measurement,were employed.It has been demonstrated that nanobubbles significantly enhanced the flotation recovery of galena and its flotation selectivity from pyrite,as compared to the conventional flotation process.The preferential formation of nanobubbles on the galena surface,which is more hydrophobic than pyrite surface,further increased the surface hydrophobicity and agglomeration of galena particles.The introduction of nanobubbles into the flotation system also increased in the maximum TPCL length and detachment length between the galena surface and bubbles,contributing to the enhanced flotation efficiency.
基金supported by the National Natural Science Foundation of China(Grant Nos.12022508,12074394,and 22125604)Shanghai Supercomputer Center of ChinaShanghai Snowlake Technology Co.Ltd.
文摘The stable nanobubbles adhered to mineral surfaces may facilitate their efficient separation via flotation in the mining industry.However,the state of nanobubbles on mineral solid surfaces is still elusive.In this study,molecular dynamics(MD)simulations are employed to examine mineral-like model surfaces with varying degrees of hydrophobicity,modulated by surface charges,to elucidate the adsorption behavior of nanobubbles at the interface.Our findings not only contribute to the fundamental understanding of nanobubbles but also have potential applications in the mining industry.We observed that as the surface charge increases,the contact angle of the nanobubbles increases accordingly with shape transformation from a pancake-like gas film to a cap-like shape,and ultimately forming a stable nanobubble upon an ordered water monolayer.When the solid–water interactions are weak with a small partial charge,the hydrophobic gas(N_(2))molecules accumulate near the solid surfaces.However,we have found,for the first time,that gas molecules assemble a nanobubble on the water monolayer adjacent to the solid surfaces with large partial charges.Such phenomena are attributed to the formation of a hydrophobic water monolayer with a hydrogen bond network structure near the surface.
基金Project supported by the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2022GXNSFAA035487)the National Natural Science Foundation of China (Grant Nos. 12272100, 11474285, and 12074382)+2 种基金the Graduate Education Innovation Project of Guangxi Zhuang Autonomous Region, China (Grant No. XJCY2022012)the Guangxi Normal University Ideological and Political Demonstration Course Construction Project (Grant Nos. 2022kcsz15 and 2023kcsz29)the Innovation Project of Graduate Education of Guangxi Zhuang Autonomous Region, China (Grant No. YCBZ2024087)。
文摘We study the effects of gas adsorption on the dynamics and stability of nanobubbles at the solid–liquid interface. The phase diagram and dynamic evolution of surface nanobubbles were analyzed under varying equilibrium adsorption constant.Four distinct dynamic behaviors appear in the phase diagram: shrinking to dissolution, expanding to bursting, shrinking to stability, and expanding to stability. Special boundary states are identified in phase diagram, where the continuous growth of nanobubbles can take place even under very weak gas–surface interaction or with very small initial bubble size. Surface adsorption plays a critical role in the stability, lifetime, radius, and contact angle of nanobubbles, thereby demonstrating that pinning is not a prerequisite for stabilization. Furthermore, stable equilibrium nanobubbles exhibit a characteristic range of footprint radius, a limited height, and a small contact angle, consistent with experimental observations.
基金financial support from the National Natural Science Foundation of China(No.21775003)Anhui Provincial Natural Science Foundation(No.2308085MB56)the Key Project of Anhui Provincial Department of Education Scientific Research Project(No.2023AH040032).
文摘Taking advantage of the extremely small size of the gold nanodisk electrode,the single hydrogen nanobubble generated on the surface of the nanoelectrode was studied to evaluate its hydrogen evolution performance.It was found that compared with the bare gold nanodisk electrode,the bubble formation potential of the gold nanodisk electrode modified with tungsten disulfide quantum dots(WS_(2)QDs)on the surface was more positive,indicating that its hydrogen evolution activity was higher.Microdynamic model analysis shows that the average standard rate constant of the rate-determining step of the hydrogen evolution reaction of gold nanoelectrodes modified with WS_(2)QDs is approximately 12 times larger than that of gold nanoelectrodes.This work based on the formation of nanobubbles provides new ideas for the design and performance evaluation of hydrogen evolution reaction catalysts.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874379,11575281,and U1532260)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KJZD-EW-M03and QYZDJ-SSW-SLH019)。
文摘The anoxia of coastal water has already been a serious problem all over the word.Nanobubbles are proved to have great applications in water remediation because they could effectively increase the oxygen content and degrade organic matters in water.But the existing methods to produce nanobubbles are complicated and high cost to operate,especially in deep sea.In this paper,we presented a low-cost method,hydraulic air compression(HAC),to produce a large number of nanobubbles and proved that nanoscale gas bubbles could be produced by HAC for the first time.Nanoparticle tracking analysis was used to measure the size and concentration of produced nanobubbles.It indicated that the concentration of nanobubbles would increase as the downpipe height increases.Degassed measurements proved that produced“nanoparticles”are gas nanobubbles indeed.More dissolved oxygen in water would provide the source for larger number of nanobubble formation.Those results are expected to be very helpful for water remediation in ocean in the future.
基金the Florida In-stitute of Phosphate Research (FIPR)the Center for Advanced Separation Technologies (CAST)the National Natural Science Foundation of China (Nos.50921002 and 90510002) for the financial support
文摘A special nanobubble generation system has been developed for evaluating the effect of nanobubble on froth flotation. In this study, an eight-factor five-level Central Composite Experimental Design was conducted for investigating eight important parameters governing the median size and the volume of nanobubbles. These process parameters included surfactant concentration, dissolved oxygen (O2) content, dissolved carbon dioxide gas (CO2) content, pressure drop in cavitation tube nozzle, <50 nm hydrophobic particle concentration, <50 nm hydrophilic particle concentration, slurry temperature and the time interval after nanobubble generation. The properties, stability and uniformity of nanobubbles were investigated. The study of the produced nanobubble’s effects on the characteristics of microbubble solutions and millimeter scale bubble solutions was performed in a 50.8 mm column.
文摘Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing plants to reduce milling cost and increase valuable mineral recovery. Based on this, the effects of nanobubbles(NBs) and hydrodynamic parameters on coarse quartz particle flotation were systematically investigated. Mechanical flotation experiments were carried out using the 7 cm and 9 cm diameter impellers in order to produce different hydrodynamic conditions. 900–1300 rpm impeller speeds were used for the 7 cm diameter impeller and 554–786 rpm for the 9 cm diameter impeller. The results show that the presence of NBs increased the flotation recovery of à425 + 106 lm quartz by up to 21%. For the7 cm diameter impeller, the maximum flotation recoveries of 86.4% and 98% were obtained in the absence and presence of NBs at Reynolds number(Re) of 81,000 and 66,000, respectively. For the 9 cm diameter impeller, the maximum recoveries of 86.3% and 97.5% were obtained in the absence and presence of NBs at Re of 90,000 and 75,000, respectively. NBs increased the flotation rate constant up to 36%.
基金The Center for Advanced Separation Technologies (CAST) and the National Natural Science Foundation of China (Nos.50921002 and 90510002) for the financial support
文摘Froth flotation is a commonly employed technology to improve the quality of raw coal and minerals.Coal and minerals particle size and surface hydrophobicity are two main parameters that affect three key steps in froth flotation process:particle-bubble collision,adhesion,and detachment.This paper fundamentally investigated the effects of nanobubble on coal and phosphate flotation.It has been found that the presence of nanobubble in flotation pulp could widen the coal and phosphate flotation particle size range,increase the particle surface hydrophobicity,and thus improve the coal and phosphate froth flotation recovery.
文摘Nanobubble flotation technology is an important research topic in the field of fine mineral particle separation.The basic characteristics of nanobubbles,including their size,concentration,surface zeta potential,and stability have a significant impact on the nanobubble flotation performance.In this paper,bulk nanobubbles generated based on the principle of hydrodynamic cavitation were investigated to determine the effects of different parameters(e.g.,surfactant(frother)dosage,air flow,air pressure,liquid flow rate,and solution pH value)on their size distribution and zeta potential,as measured using a nanoparticle analyzer.The results demonstrated that the nanobubble size decreased with increasing pH value,surfactant concentration,and cavitation-tube liquid flow rate but increased with increasing air pressure and increasing air flow rate.The magnitude of the negative surface charge of the nanobubbles was positively correlated with the pH value,and a certain relationship was observed between the zeta potential of the nanobubbles and their size.The structural parameters of the cavitation tube also strongly affected the characteristics of the nanobubbles.The results of this study offer certain guidance for optimizing the nanobubble flotation technology.
基金supported by the Fundamental Research Funds for the Central Universities (No. 2019XKQYMS45)。
文摘Physical upgrading of graphite is typically achieved with many stages of grinding and flotation to produce a concentrate with approximately 95% carbon grade.An innovative grinding and column flotation process has been developed for efficient graphite upgrading to substantially simplify the process flowsheet and reduce operating costs.In this process,a high-pressure grinding roller(HPGR) and a stirred mill were employed as primary comminution techniques and a nanobubble flotation column as a key separation process.The results obtained with a crystalline flake graphite sample with a carbon grade of 11.15% show that the novel process can produce a concentrate with 94.82% carbon grade and 97.89% recovery from an open circuit of one rougher and two cleaner flotation stages.Scanning electron microscope(SEM)microphotographs indicate that HPGR offers the advantage of more effective protection of graphite flakes during crushing.Grinding test results show that stirred mill could not only protect graphite flakes but also promote the efficient liberation of graphite.Compared with the traditional flotation process,nanobubble flotation can effectively recover ultrafine graphite.The new process possesses a number of important advantages over the traditional method,including substantially higher graphite recovery,greatly simplified process flowsheet,better protection of flake size,reduced reagent consumption and process costs,etc.
基金the Florida Institute of Phosphate Research(FIPR),The Center for Advanced Separation Technologies(CAST) and the National Natural Science Foundation of China (Nos.50921002 and 90510002) for the financial supportCF Industry Inc and Mosaic Company for supplying specimens and ArrMaz Custom Chemicals Inc.for providing chemicals employed in this study.
文摘Froth flotation is used widely for upgrading raw phosphate.The flotation recovery of coarse phosphate(-1.18+0.425 mm) is much lower than that achieved on the-0.425+0.15 mm size fraction.Enhanced recovery of coarse phosphate particles is of great economic and environmental importance for phosphate industry.In this investigation,four different phosphate samples were aquired,characterized and tested in a specially designed laboratory-scale flotation column.Significant recovery improvement of coarse phosphate flotation was achieved using cavitation-generated nanobubble though its effects differ among the four testing phosphate samples.The laboratory-scale flotation column test results indicate that nanobubble increased P_2O_5 recovery by up to 10%～30%for a given Acid Insoluble(A.I.) rejection,depending on the characteristic of phosphate samples.The improvement effect of nanobubble on the hard-to-float particles was more significant than that on easy-to-float particles,especially at lower collector dosages.Nanobubbles reduced the collector dosage by 1/3 to 1/2.Nanobubbles almost doubled the coarse phosphate flotation rate constant and increased the flotation selectivity index by up to 25%.
文摘Coal is the world's most abundant fossil fuel.Coal froth flotation is a widely used cleaning process to separate coal from mineral impurities.Flotation of coarse coal particles,ultrafine coal particles and oxidized coal particles is well known to be difficult and complex.In this paper,the nanobubbles' effects on the flotation of the varying particle size,particle density and floatability coal samples were evaluated using a bank of pilot scale flotation cells,a laboratory scale and a pilot scale specially designed flotation column.The parameters evaluated during this study include the flow rate ratio between the nanobubble generator and the conventional size bubble generator,the superficial air velocity,collector dosage,frother concentration,flotation feed rate,feed solids concentration,feed particle size,and the superficial wash water flow rate,etc.The results show that the use of nanobubbles in a bank of mechanical cells flotation and column flotation increased the flotation recovery by 8%～27% at a given product grade.Nanobubbles increased the flotation rate constants of 600～355,355～180,180～75,and 75～0 microns size coal particles by 98.0%,98.4%,50.0% and 41.6%,respectively.The separation selectivity index was increased by up to 34%,depending on the flotation feed characteristics and the flotation conditions.
基金funded by a number of government and industrial grants,particularly the grant from the National Natural Science Foundation of China(No.51804188)。
文摘Froth flotation is often used for fine-particle separation,but its process efficiency rapidly decreases with decreasing particle size.The efficient separation of ultrafine particles(UFPs)has been a major challenge in the mineral processing field for many years.In recent years,the use of surface nanobubbles in the flotation process has been recognized as an effective approach for enhancing the recovery of UFPs.Compared with traditional macrobubbles,nanobubbles possess unique surface and bulk characteristics,and their effects on the UFP flotation behavior have been a topic of intensive research.This review article is focused on the studies on various unique characteristics of nanobubbles and their mechanisms of enhancing the UFP flotation.The purpose of this article is to summarize the major achievements on the two topics and pinpoint future research needs for a better understanding of the fundamentals of surface nanobubble flotation and developing more feasible and efficient processes for fine and UFPs.
文摘Although various and unique properties of bulk nanobubbles have drawn researchers'attention over the last few years,their formation and stabilization mechanism has remained unsolved.In this paper,we use ultrasonic methods to produce bulk nanobubbles in the pure water and give a comprehensive study on the bulk nanobubbles properties and generation.The ultrasonic wave gives rise to constant oscillation in water where positive and negative pressure appears alternately.With the induced cavitation and presence of dissolved air,the bulk nanobubbles formed."Nanosight"(which is a special instrument that combines dynamic light scattering with nanoparticle tracking analysis)was used to analyze the track and concentration of nanobubbles.Our results show that in our experiment,sufficient bulk nanobubbles were generated and we have proven they are not contaminations.We also found nanobubbles in the ultrasonic water change in both size and concentration with ultrasonic time.
基金the National Natural Science Foundation of China(No.91434204)。
文摘In theory,nanobubbles can stably exist with a lifetime of microseconds at most,but numerous experimental observations demonstrate that nanobubbles in bulk solution can be stable from hours to weeks.Although various conjectures on the stability mechanism of bulk nanobubbles,such as the contaminant mechanism,skin mechanism,surface zeta potential mechanism,are proposed,there has not yet been a unified conclusion.Since bulk nanobubbles show great potential in a wide spectrum of applications and are relevant to a number of unsolved questions on cavitation and nucleation,the debate over their stability mechanisms has been active.In the past,extensive studies have been carried out to understand the mechanism of nanobubble stability,and important insights have already been provided.This paper will provide a brief overview of our current understanding of the unexpected stability of bulk nanobubbles.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 20403010 and 10335070） and the Science and Technology Commission of Shanghai Municipality （Grant Nos 0352nm116 and 0452nm007）.
文摘The great implication of nanobubbles at a solid/water interface has drawn wide attention of the scientific community and industries. However, the fundamental properties of nanobubbles remain unknown as yet. In this paper, the temperature effects on the morphology of nanobubbles at the mica/water interface are explored through the combination of AFM direct image with the temperature control. The results demonstrate that the apparent height of nanobubbles in AFM images is kept almost constant with the increase of temperature, whilst the lateral size of nanobubbles changes significantly. As the temperature increases from 28℃ to 42℃, the lateral size of nanobubbles increases, reaching a maximum at about 37℃, and then decreases at a higher temperature. The possible explanation for the size change of nanobubbles with temperature is suggested.
基金financially supported by the National Natural Science Foundation of China(Nos.U2003129 and 51504175)China Scholarship Council(No.201706955031)。
文摘Adhesion is an important process of particle-bubble interaction in fine particle(-10μm)flotation.This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera,atomic force microscope(AFM),adsorption capacity tests,and induction time tests.After being pretreated with nanobubbles(NBs)water,fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid(CHA)as a collector.The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage.The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration.The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals.Since NBs played a part of the role of collector,it can improve the flotation effect while reducing the amount of collector.The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles.On the other hand,NBs agglomerate cassiterite particles,increasing the probability of particles colliding with bubbles.
基金supported by the Key Laboratory of Interfacial Physics and Technology,Chinese Academy of Sciences,the Open Research Project of the Large Scientific Facility of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.11079050,11290165,11305252,11575281,and U1532260)+3 种基金the National Key Basic Research Program of China(Grant Nos.2012CB825705 and 2013CB932801)the National Natural Science Foundation for Outstanding Young Scientists,China(Grant No.11225527)the Shanghai Academic Leadership Program,China(Grant No.13XD1404400)the Program of the Chinese Academy of Sciences(Grant Nos.KJCX2-EW-W09 and QYZDJ-SSW-SLH019)
文摘Interfacial gaseous nanobubbles which have remarkable properties such as unexpectedly long lifetime and significant potential applications, are drawing more and more attention. However, the recent dispute about the contamination or gas inside the nanobubbles causes a large confusion due to the lack of simple and clean method to produce gas nanobubbles. Here we report a convenient and clean method to effectively produce interfacial nanobubbles based on a pure water system. By adding the cold water cooled at 4 ℃ for more than 48 h onto highly oriented pyrolytic graphite （HOPG） surface, we find that the average density and total volume of nanobubbles are increased to a high level and mainly dominated by the concentrations of the dissolved gases in cold water. Our findings and methods are crucial and helpful for settling the newly arisen debates on gas nanobubbles.
基金Funding by the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant No.648124)is acknowledged with gratitudeS.S.acknowledges the support of a VLAIO Grant(Grant Number:HBC.2017.0542.)+2 种基金J.C.F.(FWO Grant 1210120 N)J.V.H(FWO-SB grant 1S62519N)and R.X.(FWO Grants 1500418 N and 12Q8718N)gratefully acknowledge the financial support by the Flemish Research FoundationL.V.H.is a junior assistant of the Department of Biomedical Molecular Biology.
文摘Efficient and safe cell engineering by transfection of nucleic acids remains one of the long-standing hurdles for fundamental biomedical research and many new therapeutic applications,such as CAR T cell-based therapies.mRNA has recently gained increasing attention as a more safe and versatile alternative tool over viral-or DNA transposon-based approaches for the generation of adoptive T cells.However,limitations associated with existing nonviral mRNA delivery approaches hamper progress on genetic engineering of these hard-to-transfect immune cells.In this study,we demonstrate that gold nanoparticle-mediated vapor nanobubble(VNB)photoporation is a promising upcoming physical transfection method capable of delivering mRNA in both adherent and suspension cells.Initial transfection experiments on HeLa cells showed the importance of transfection buffer and cargo concentration,while the technology was furthermore shown to be effective for mRNA delivery in Jurkat T cells with transfection efficiencies up to 45%.Importantly,compared to electroporation,which is the reference technology for nonviral transfection of T cells,a fivefold increase in the number of transfected viable Jurkat T cells was observed.Altogether,our results point toward the use of VNB photoporation as a more gentle and efficient technology for intracellular mRNA delivery in adherent and suspension cells,with promising potential for the future engineering of cells in therapeutic and fundamental research applications.
