Air Nanobubbles Research Articles

Stability and Free Radical Production for CO2 and H2 in Air Nanobubbles in Ethanol Aqueous Solution.

In this study, 8% hydrogen (H2) in argon (Ar) and carbon dioxide (CO2) gas nanobubbles was produced at 10, 30, and 50 vol.% of ethanol aqueous solution by the high-speed agitation method with gas. They became stable for a long period (for instance, 20 days), having a high negative zeta potential (−40 to −50 mV) at alkaline near pH 9, especially for 10 vol.% of ethanol aqueous solution. The extended Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory was used to evaluate the nanobubble stability. When the nanobubble in ethanol alkaline aqueous solution changed to an acidic pH of around 5, the zeta potential of nanobubbles was almost zero and the decrease in the number of nanobubbles was identified by the particle trajectory method (Nano site). The collapsed nanobubbles at zero charge were detected thanks to the presence of few free radicals using G-CYPMPO spin trap reagent in electron spin resonance (ESR) spectroscopy. The free radicals produced were superoxide anions at collapsed 8%H2 in Ar nanobubbles and hydroxyl radicals at collapsed CO2 nanobubbles. On the other hand, the collapse of mixed CO2 and H2 in Ar nanobubble showed no free radicals. The possible presence of long-term stable nanobubbles and the absence of free radicals for mixed H2 and CO2 nanobubble would be useful to understand the beverage quality.

Air nanobubbles (ANBs) incorporated sandwich-structured carbon nanotube membranes (CNM) for highly permeable and stable forward osmosis

The selective transport of water/ions through conventional forward osmosis (FO) membranes is largely impeded by solution-diffusion and internal concentration polarization (ICP). Herein, we report a novel air nanobubbles (ANBs) incorporated sandwich-structured carbon nanotube membrane (CNM) for highly permeable and stable FO desalination by taking advantage of the nanofluidic transport at the solid/liquid/vapor interface. Fluorinated multi-walled carbon nanotubes (F-MWCNTs) were assembled as the superhydrophobic interlayer between a hydrophilic cellulose acetate (CA) layer and a hydrophilic polyacrylonitrile (PAN) nanofibrous layer. The trapped ANBs in the superhydrophobic F-MWCNT layer crucially regulated the continuous water flow and effectively prevented salt diffusion. When tested with DI water as feed solution (FS) and 1 ​M NaCl as draw solution (DS), the ANBs incorporated sandwich-structured CNM achieved high water flux (158.0 ​L ​m−2 ​h−1) and ultralow reverse salt flux (0.4 ​g ​m−2 ​h−1) simultaneously, far beyond the state-of-the-art FO membranes. The PAN nanofibrous layer well protected the entrapped ANBs to allow a more durable FO performance. An ANBs-regulated nanofluidic flow model was proposed to elucidate selective water/salt transport mechanism. This work revealed the feasibility of ANBs incorporated membranes for osmosis-driven processes.

Effect of Air Nanobubbles on Oxygen Transfer, Oxygen Uptake and, Diversity of Aerobic Microbial Consortium in Activated Sludge Reactors

Effect of Air Nanobubbles on Oxygen Transfer, Oxygen Uptake and, Diversity of Aerobic Microbial Consortium in Activated Sludge Reactors

Development of a continuous membrane nanobubble generation method applicable in liquid food processing

SummaryA novel continuous nanobubble generation method was developed using a commercial ceramic membrane as a nanobubble generator. CO2 and air were infused externally across the ceramic membrane (pore size 50 nm) into the water flowing inside the ceramic membrane tube. Infusion of each gas was done in a single (20 s) and multiple passes (180 s) at 20–21°C. Results showed that gaseous nanobubbles could be generated even in a single pass. Low power ultrasound (200 kHz, 30W) was applied for the rapid assessment of nanobubble stability. Single‐pass ultrasound treatment of the samples was carried out at two levels: 2.6 and 5.1 J mL−1. Among the samples in which gases were infused for multiple passes, air nanobubbles were found more stable than CO2. In contrast, an opposite trend was observed in those samples in which gases were infused in the single‐pass only (20 s). This process has the potential to be applied to food processing industries, such as to enhance the products’ sensory attributes, the efficiency of membrane separation, food drying and liquid food transportation systems.

Do Gas Nanobubbles Enhance Aqueous Photocatalysis? Experiment and Analysis of Mechanism

The performance of photocatalytic advanced oxidation must be improved in order for the technology to make the jump from academic research to widespread use. Research is needed on the factors that cause photocatalysis to become self-limiting. In this study, we introduced, for the first time, nanobubbles continuously into a running photocatalytic reactor. Synthetic air, O2, and N2 bubbles in the size range of 40 to 700 nm were added to a reaction system comprising P25 TiO2 photocatalyst in stirred aqueous solution excited by UV-A lamps, with methyl orange as a target contaminant. The removal of methyl orange was tested under conditions of changing pH and with the addition of different radical scavengers. Results indicated that the oxygen and air nanobubbles improved the photocatalytic degradation of methyl orange—the removal efficiency of methyl orange increased from 58.2 ± 3.5% (N2 aeration) to 71.9 ± 0.6% (O2 aeration). Dissolved oxygen (DO) of 14.93 ± 0.13 mg/L was achieved using O2 nanobubbles in comparison to 8.43 ± 0.34 mg/L without aeration. The photodegradation of methyl orange decreased from 70.8 ± 0.4% to 53.9 ± 0.5% as pH increased from 2 to 10. Experiments using the scavengers showed that O2− was the main reactive species in photocatalytic degradation under highly dissolved oxygen conditions, which also accounted for the observation that the removal efficiency for methyl orange decreased at higher pH. However, without photocatalyst, nanobubbles alone did not improve the removal of methyl orange, and nanobubbles also did not increase the degradation of methyl orange by only photolysis. These experiments show that oxygen and air nanobubbles can act as environmentally friendly catalysts for boosting the performance of photocatalytic water treatment systems.

Reduction of organic and biological pollutants from affluents of the Ancón wastewater treatment plant using microanobubbles of air and graphene [Reducción de contaminantes orgánicos y biológicos de afluentes de la planta de tratamiento de aguas residuales de Ancón utilizando micronanoburbujas de aire y grafeno

The objective of this research was to reduce the organic and biological load of tributaries of the Ancón Wastewater Treatment Plant using microanobubbles of air and graphene. A preliminary sample of the affluent (3L) was taken, which had an initial concentration of Biochemical Oxygen Demand (BOD5) of 410 mg/L, Chemical Oxygen Demand (COD) of 483 mg/L, Thermotolerant Coliforms of 44,000 NMP/100mL and turbidity of 63.33 NTU. The experimental part was carried out with 03 samples of 20 liters with 03 repetitions with a treatment time of 20, 40 and 60 minutes applying air nanobubbles and 6, 12 and 18 grams of graphene respectively. The results of the treated samples were: 87 mg/L representing 78.8% reduction in Biochemical Oxygen Demand (BOD5), 114 mg/L representing 76.4% reduction in Chemical Oxygen Demand (COD), 2,900 NMP/100mL that represents 93.41% reduction of Thermotolerant Coliforms and 12.4 NTU that represents 80.11% reduction of turbidity.

Capillary deformation of ultrathin glassy polymer films by air nanobubbles

Confined glasses and their anomalous interfacial rheology raise important questions in fundamental research and numerous practical applications. In this Letter, we study the influence of interfacial air nanobubbles on the free surface of ultrathin high-molecular-weight glassy polystyrene films immersed in water, in ambient conditions. In particular, we reveal the counterintuitive fact that a soft nanobubble is able to deform the surface of a rigid glass, forming a nanocrater with a depth that increases with time. By combining in-situ atomic-force-microscopy measurements and a modified lubrication model for the liquid-like layer at the free surface of the glass, we demonstrate that the capillary pressure in the nanobubble together with the liquid-like layer at the free surface of the glass determine the spatiotemporal growth of the nanocraters. Finally, from the excellent agreement between the experimental profiles and the numerical solutions of the governing glassy thin-film equation, we are able to precisely extract the surface mobility of the glass. In addition to revealing and quantifying how surface nanobubbles deform immersed glasses, until the latter eventually dewet from their substrates, our work provides a novel, precise, and simple measurement of the surface nanorheology of glasses.

Stability of pinned surface nanobubbles against expansion: Insights from theory and simulation

While growth and dissolution of surface nanobubbles have been widely studied in recent years, their stability under pressure changes or a temperature increase has not received the same level of scrutiny. Here, we present theoretical predictions based on classical theory for pressure and temperature thresholds (pc and Tc) at which unstable growth occurs for the case of air nanobubbles on a solid surface in water. We show that bubbles subjected to pinning have much lower pc and higher Tc compared to both unpinned and bulk bubbles of similar size, indicating that pinned bubbles can withstand a larger tensile stress (negative pressure) and higher temperatures. The values of pc and Tc obtained from many-body dissipative particle dynamics simulations of quasi-two-dimensional (quasi-2D) surface nanobubbles are consistent with the theoretical predictions, provided that the lateral expansion during growth is taken into account. This suggests that the modified classical thermodynamic description is valid for pinned bubbles as small as several nanometers. While some discrepancies still exist between our theoretical results and previous experiments, further experimental data are needed before a comprehensive understanding of the stability of surface nanobubbles can be achieved.

Reduction of the pollutants concentration in the effluents of the fish canning industry using air nanobubbles, Callao [Reducción de la concentración de contaminantes en los efluentes de la industria de conservas de pescado utilizando nanoburbujas de aire, Callao

The present investigation was carried out with the purpose of evaluating the reduction of pollutants in the effluents tested from the fish canning industry using air nanobubbles. The study was carried out on a laboratory scale using air nanobubble generator equipment. The results were reduced by 89.5% of total suspended solids (from 6180 mg/L to 645 mg/L), 76.5% of BOD5 (from 7350 mgO2/L to 1730 mgO2/L), 73.6% of COD (from 10356 mgO2/L to 2735 mgO2/L) and 79.4% of oils and fats (from 96.3 mg/L to 33.2 mg/L). It was concluded that the treatment using air nanobubbles can significantly reduce the concentration of the pollutants present in the effluents of the fish canning industry.

Multistable interaction between a spherical Brownian particle and an air-water interface.

We report the measurement of the interaction energy between a charged Brownian polystyrene particle and an air-water interface. The interaction potential is obtained from the Boltzmann equation by tracking particle interface distance with a specifically designed Dual-Wave Reflection Interference Microscopy (DW-RIM) setup. The particle has two equilibrium positions located at few hundreds of nanometers from the interface. The farthest position is well accounted by a DLVO model complemented by gravity. The closest one, not predicted by current models, more frequently appears in water solutions at relatively high ions concentrations, when electrostatic interaction is screened out. It is accompanied by a frozen rotational diffusion dynamics that suggests an interacting potential dependent on particle orientation and stresses the decisive role played by particle surface heterogeneities. Building up on both such experimental results, the important role of air nanobubbles pinned on the particle interface is discussed.

Application of air nanobubbles in washing sewage of a Soft drink bottling plant [Aplicación de nanoburbujas de aire en aguas residuales de lavado de una Embotelladora de Bebidas Carbonatadas

The research’s purpose was to apply air nanobubbles in washing sewage of a soft drink bottling plant. The methodology used was pre-experimental and applied. The air nanobubbles were applied in the 3 samples of 20 liters of washing sewage of a Soft drink bottling plant, from which 2 samples were extracted: one at 45 minutes and another at 90 minutes after starting treatment. The results showed that air nanobubbles reduced the concentration of: conductivity by 8.4% (from 2500 mS/cm to 2290 mS/cm), turbidity by 71.97% (from 152 NTU to 42.6 NTU), BOD5 by 99.89% (from 1892.7 mg/L to 1.9 mg/L) and COD in 99.13% (from 3681 mg/L to 32 mg/L).

On the Stability of Nanobubbles in Water

Conditions of stability of charged air nanobubbles in water are considered. Ranges of values of the charge and radius in which coalescence and division predominate are theoretically determined. The stability region is revealed in which the given processes are thermodynamically improbable. A comparison of the theory with the available experiment is performed. Based on the results of our analysis, it is concluded that the main stabilizing factor for nanosized particles is their surface charge.

Oxygen and air nanobubbles in water inhibit proliferation of dental follicle stem cells in vitro

Background Nanobubbles NBs are small gas particles with diameters less than nm and have unique properties such as long retention times and high gas content in liquids Oxygen and air NBs are reportedly bioactive promoting growth in animals however there are few reports on the mechanisms governing such effects Accordingly this study investigated the effects of oxygen and air NBs on the proliferation of dental follicle stem cells DFSCs in vitro Methods DFSCs were obtained from an impacted supernumerary tooth The cells were cultured with Dulbecco rsquo s modified Eagle rsquo s medium containing oxygen or air NBs water for or days Each cell number was measured by a colorimetric assay using CCK nbsp Results and discussion Oxygen and air NBs significantly inhibited cell proliferation in a dose dependent manner However there was no significant difference between oxygen and air NBs media High oxygen content may have inhibited cell proliferation nbsp

Reduction of COD and TSS of waste effluents from a sugar industry through the use of air micro-nanobubbles

The sugar industry uses large volumes of water for its production process. The discharge of effluents is one of the main problems that affects mainly rivers, seas, resulting in the high level of pollution that captures plant and aquatic life. The objective of this research is to reduce the concentration of Chemical Oxygen Demand and Total Suspended Solids by treating air nanobubbles. The experiment was carried out with a sample of sugar process effluent having as the initial concentration value of the Chemical Oxygen Demand of 412.15 mg O2/L. and Total Suspended Solids of 620 mg TSS/L. After treating the water in a time of 90 minutes it was obtained as final result the Chemical Oxygen Demand was 66.13 mg O2 /L and Total Suspended Solids 131 mg TSS/L, improving water quality as well as for reuse for another type of use.

Ceramic membrane defouling (cleaning) by air Nano Bubbles.

Ceramic membranes are among the most promising technologies for membrane applications, owing to their excellent resistance to mechanical, chemical, and thermal stresses. However, membrane fouling is still an issue that hampers the applications at large scales. Air Nano Bubbles (NBs), due to high mass transfer efficiency, could potentially prevent fouling of ceramic membrane filtration processes. In this study, bench and pilot scale ceramic membrane filtration was performed with air NBs to resist fouling. To simulate fouling, humic acid, as an organic foulant, was applied to the membrane flat sheet surface. Complete membrane clogging was achieved in less than 6 h. Membrane defouling (cleaning) was performed by directly feeding of air NBs to the membrane cells. The surface of the ceramic membrane was superbly cleaned by air NBs, as revealed by atomic force microscope (AFM) images before and after the treatment. The permeate flux recovered to its initial level (e.g., 26.7 × 10(-9) m(3)/m(2)/s at applied pressure of 275.8 kPa), which indicated that NBs successfully unclogged the pores of the membrane. The integrated ceramic membrane and air NBs system holds potential as an innovative sustainable technology.

Stable Encapsulated Air Nanobubbles in Water.

The dispersion into water of nanocapsules bearing a highly hydrophobic fluorinated internal lining yielded encapsulated air nanobubbles. These bubbles, like their micrometer-sized counterparts (microbubbles), effectively reflected ultrasound. More importantly, the nanobubbles survived under ultrasonication 100-times longer than a commercial microbubble sample that is currently in clinical use. We justify this unprecedented stability theoretically. These nanobubbles, owing to their small size and potential ability to permeate the capillary networks of tissues, may expand the applications of microbubbles in diagnostic ultrasonography and find new applications in ultrasound-regulated drug delivery.

Stable Encapsulated Air Nanobubbles in Water

AbstractThe dispersion into water of nanocapsules bearing a highly hydrophobic fluorinated internal lining yielded encapsulated air nanobubbles. These bubbles, like their micrometer‐sized counterparts (microbubbles), effectively reflected ultrasound. More importantly, the nanobubbles survived under ultrasonication 100‐times longer than a commercial microbubble sample that is currently in clinical use. We justify this unprecedented stability theoretically. These nanobubbles, owing to their small size and potential ability to permeate the capillary networks of tissues, may expand the applications of microbubbles in diagnostic ultrasonography and find new applications in ultrasound‐regulated drug delivery.

The continuous generation of hydrogen peroxide in water containing very low concentrations of unsymmetrical dimethylhydrazine

Continuous generation of hydrogen peroxide catalyzed by low concentrations of 1,1-dimethylhydrazine (heptyl)--a rocket fuel component--in air saturated water was shown by the method of enhanced chemiluminescence in the system of luminol-p-iodophenol-peroxidase. The concentration dependence and the influence of heat and light on the formation of hydrogen peroxide in the water under the influence of dimethylhydrazine at concentrations considerably lower than maximum allowable concentrations were studied, and the physical-chemical mechanism of this process was considered. It is supposed that dimethylhydrazine at ultra-low concentrations is associated with air nanobubbles and represents a long-lived complex performing catalysis of hydrogen peroxide formation under the influence of heat and light. We put forward the new concept of.toxicity of dimethylhydrazine at very low concentrations due to violation of homeostasis of reactive oxygen species formation in aqueous solutions entering the body of humans and animals.

Bovine serum albumin film as a template for controlled nanopancake and nanobubble formation: In situ atomic force microscopy and nanolithography study

Air nanobubbles and nanopancakes were investigated in situ by both tapping mode atomic force microscopy (TM AFM) and atomic force nanolithography techniques employing bovine serum albumin (BSA) film supported by highly oriented pyrolytic graphite (HOPG). The BSA denaturation induced by the water-to-ethanol exchange served for conservation of nanobubble and nanopancake sites appearing as imprints in BSA film left by gaseous cavities formerly present on the interface in the aqueous environment. Once the BSA film was gently removed by the nanoshaving technique applied in ethanol, a clean basal plane HOPG area with well-defined dimensions was regenerated. The subsequent reverse ethanol-to-water exchange led to the re-formation of nanopancakes specifically at the nanoshaved area. Our approach paves the way for the study of gaseous nanostructures with defined dimensions, formed at solid–liquid interface under controlled conditions.

Effects of static magnetic field on water at kinetic condition

Water was exposed for different times to weak static magnetic field (MF) generated from a stack of magnets ( B = 15 mT) or from a single permanent magnet ( B = 0.27 T) at flow conditions. The water conductivity and the amount of evaporated water were measured as a function of time following the application of MF. It was found that the MF decreases the water conductivity, which is inversely proportional to the flow rate, and increases the amount of evaporated water, even after the water's distillation. The effects are due to the hydrogen bond network strengthening and the perturbation of gas/liquid interface from the air nanobubbles in the water.