Use Of Nanobubbles Research Articles

Use of Nanobubbles to Improve Mass Transfer in Bioprocesses

Nanobubble technology has emerged as a transformative approach in bioprocessing, significantly enhancing mass-transfer efficiency for effective microbial activity. Characterized by their nanometric size and high internal pressure, nanobubbles possess distinct properties such as prolonged stability and minimal rise velocities, allowing them to remain suspended in liquid media for extended periods. These features are particularly beneficial in bioprocesses involving aerobic strains, where they help overcome common obstacles, such as increased culture viscosity and diffusion limitations, that traditionally impede efficient mass transfer. For instance, in an experimental setup, nanobubble aeration achieved 10% higher soluble chemical oxygen demand (sCOD) removal compared to traditional aeration methods. Additionally, nanobubble-aerated systems demonstrated a 55.03% increase in caproic acid concentration when supplemented with air nanobubble water, reaching up to 15.10 g/L. These results underscore the potential of nanobubble technology for optimizing bioprocess efficiency and sustainability. This review delineates the important role of the mass-transfer coefficient (kL) in evaluating these interactions and underscores the significance of nanobubbles in improving bioprocess efficiency. The integration of nanobubble technology in bioprocessing not only improves gas exchange and substrate utilization but also bolsters microbial growth and metabolic performance. The potential of nanobubble technology to improve the mass-transfer efficiency in biotechnological applications is supported by emerging research. However, to fully leverage these benefits, it is essential to conduct further empirical studies to specifically assess their impacts on bioprocess efficacy and scalability. Such research will provide the necessary data to validate the practical applications of nanobubbles and identify any limitations that need to be addressed in industrial settings.

An investigation of nanobubble enhanced flotation for fly ash decarbonization

Froth flotation is often employed to remove unburned carbon in the fly ash produced as a coal combustion by-product before it can be utilized in the cement or similar industries. However, with the deterioration of coal quality and environmental regulations getting stricter, fly ash has become increasingly more difficult to be purified by the flotation process and the limitations of traditional flotation techniques have become more obvious for ultrafine particles such as fly ash. Nanobubbles have proven effective in enhancing the flotation performance with fine and ultrafine particles. In this study the effect of nanobubbles on fly ash flotation decarbonization and underlying mechanisms have been investigated with a flotation column under various experimental conditions using a Chinese fly ash sample. The results have demonstrated that nanobubbles are able to significantly improve the efficiency of decarbonization of fly ash flotation. Typically the use of nanobubbles increased the recovery of unburnt carbon by 3–15 % and reduced the fly ash LOI by 0.2 %–3.5 %. It has also been shown that nanobubble flotation reduced the required dosages of frother and collector by approximately one half. New mechanisms of nanobubbles improving fly ash decarbonization flotation performance were explored from the perspectives of bubble-particle interactions and solution surface tensions.

Generation and Influence of Carbon Dioxide Nanobubbles on Physicochemical Properties Including the Surface Tension of Clarified Apple Juice

AbstractThis work aims at examining the impact of generated CO2 nanobubbles (NBs) via the membrane-based method on physicochemical properties and surface tension of commercial clarified apple juice. The gas was injected at 300 kPa pressure for variable liquid circulation times (5, 13 and 26 min) to produce the CO2 NBs. Sets of 13- and 26-min circulation time to mix CO2 and liquid gave the desirably nano-size (~ 80–200 nm) NBs and significantly (p ≤ 0.05) reduced surface tension (by ~ 20–25%) of the juice dispersed with these formed tiny gas bubbles (NB-juice). An increase in circulation time also resulted in more negative zeta potential and higher dissolved CO2 concentration of the NB-juice. Density values of apple juice remained unchanged with and without incorporating CO2 NBs. These experimental outcomes provide the potential use of NBs in controlling the characteristics of liquid food as an environment-friendly approach to minimise chemical usages.

Unlocking the Potential of Nanobubbles: Achieving Exceptional Gas Efficiency in Electrogeneration of Hydrogen Peroxide.

The electrogeneration of hydrogen peroxide (H2 O2 ) via the oxygen reduction reaction is a crucial process for advanced water treatment technologies. While significant effort is being devoted to developing highly reactive materials, gas provision systems used in these processes are receiving less attention. Here, using oxygen nanobubbles to improve the gas efficiency of the electrogeneration of H2 O2 is proposed. Aeration with nanobubbles is compared to aeration with macrobubbles under an identical experimental set-up, with nanobubbles showing a much higher gas-liquid volumetric mass transfer coefficient (KL a) of 2.6 × 10-2 min-1 compared to 2.7 × 10-4 min-1 for macrobubbles. Consequently, nanobubbles exhibit a much higher gas efficiency using 60% of O2 delivered to the system compared to 0.19% for macrobubbles. Further, it is observed that the electrogeneration of H2 O2 using carbon felt electrodes is enhanced using nanobubbles. Under the same dissolved oxygen levels, nanobubbles boost the reaction yield to 84%, while macrobubbles yield only 53.8%. To the authors' knowledge, this is the first study to investigate the use of nanobubbles in electrochemical reactions and demonstrate their ability to enhance gas efficiency and electrocatalytic response. These findings have important implications for developing more efficient chemical and electrochemical processes operating under gas-starving systems.

Nanobubble-mediated co-delivery of Ce6 and miR-195 for synergized sonodynamic and checkpoint blockade combination therapy with elicitation of robust immune response in hepatocellular carcinoma

MicroRNAs (miRNAs) is the tiny and highly conserved noncoding RNAs, regulate gene expression at the post-transcriptional level by binding to the 3′-UTR of target mRNAs. Several studies found that miR-195 plays an unavoidable role in the regulation of cell proliferation, cycle and apoptosis in hepatocellular carcinoma (HCC). Here, we constructed miR-195 and Chlorine e6 (Ce6) co-loading NBs (nanobubbles), making use of NBs as carriers to deliver miR-195 and Ce6 to mouse tumor models. Our results showed that the binding between PD-1 and PD-L1 was blocked by upregulating miR-195 expression. The analysis of CTL (Cytotoxic T Cell) immune activity in the treatment group was higher than the control group. Simultaneously, Ce6 was used as sonosensitizer to induce SDT (sonodynamic therapy) and trigger ICD (immunogenic cell death) of tumor cell via generation of ROS. Recent studies have found that ICD may further enhance anti-tumor immunity against PD-L1. Results indicated that combination treatment effectively stimulated infiltration of T cell and the activation of natural killer (NK) cells as well as the maturation of dendritic cells (DCs), and the combination treatment group exibited the highest CTL killing activity. These results indicate that a stronger antitumor immunity was triggered via combination of SDT-induced tumor cell ICD and immune checkpoint blockade of PD-1/PD-L1 mediated by upregulation of miR-195. In conclusion, we have successfully constructed an efficient delivery system with great potential to provide a new strategy for synergistic immunotherapy.

Influence of Nanobubble Size Distribution on Ultrasound-Mediated Plasmid DNA and Messenger RNA Gene Delivery.

The use of nanobubbles (NBs) for ultrasound-mediated gene therapy has recently attracted much attention. However, few studies have evaluated the effect of different NB size distribution to the efficiency of gene delivery into cells. In this study, various size of albumin stabilized sub-micron bubbles were examined in an in vitro ultrasound (1 MHz) irradiation setup in the aim to compare and optimize gene transfer efficiency. Results with pDNA showed that gene transfer efficiency in the presence of NB size of 254.7 ± 3.8 nm was 2.5 fold greater than those with 187.3 ± 4.8 nm. Similarly, carrier-free mRNA transfer efficiency increased in the same conditions. It is suggested that NB size greater than 200 nm contributed more to the delivery of genes into the cytoplasm with ultrasound. Although further experiments are needed to understand the underlying mechanism for this phenomenon, the present results offer valuable information in optimizing of NB for future ultrasound-mediate gene therapy.

Nanobubble-assisted scaling inhibition in membrane distillation for the treatment of high-salinity brine

In this study, we report the use of nanobubbles (NBs) as a simple and facile approach to effectively delay scaling in membrane distillation (MD) during the treatment of highly saline feed (100 g L−1). Unlike conventional gas bubbling in MD for improving the hydrodynamic flow conditions in the feed channel, here we generated air NBs with an average size of 128.81 nm in the feed stream and examined their impact on membrane scaling inhibition during MD operation. Due to their small size, neutral buoyancy, and negative surface charge, NBs remain in suspension for a longer time (14 days), providing homogenous mixing throughout the entire feed water. The MD performance results revealed that severe membrane scaling happened during the DCMD treatment of high salinity brine in the absence of nanobubbles, which dramatically reduced the distillate flux to zero after 13 h. A one-time addition of air NBs in the saline feed significantly reduced salt precipitation and crystal deposition on the PVDF membrane surface, delayed the occurrence of flux decline, prevented membrane wetting, thereby prolonging the effective MD operating time. With similar feed concentration and operating conditions, only 63% flux decline after 98 h operation was recorded in nanobubble-assisted MD. Two key explanations were suggested for the delayed membrane scaling upon addition of air NBs in the MD feed: (1) NB-induced turbulent flow in the feed channel that increases the surface shear forces at the membrane surface, alleviating both temperature and concentration polarization effect, (2) electrostatic attractions of the counterions to the negatively charged NBs, which reduces the availability of these ions in the bulk feed for scale formation.

Stability of Oxygen Nanobubbles under Freshwater Conditions

The use of nanobubbles (NBs) has gained significant attention in various applications (e.g., aeration in biological water treatment, water disinfection, membrane defouling, and ground water and sediment remediation) in recent decades because of their superior characteristics such as the improved mass transfer at the gas-liquid interfaces, their lifetime up to a couple of weeks, the formation of reactive oxygen species (ROS) with high oxidative potential. However, there is a lack of information about the effect of various factors on the stability of NBs for a long storage period under freshwater conditions. In this study, a comprehensive investigation was conducted to systematically examine the stability of oxygen NBs in water under various conditions which are closely related to a typical freshwater or the drinking water treatment. The oxygen NB stability in water was evaluated by monitoring the change in the bubble concentrations, size distribution, average diameter, and zeta potential for 60 days of storage time under different pH, hardness, ionic strength, natural organic matter (NOM), chlorine, and temperature conditions. In addition, the formation of hydroxyl radical (•OH) was investigated using disodium terephthalate which form fluorescent adducts with •OH in the presence of oxygen NBs. Among the parameters investigated, the impacts of cations, low pH, and high SUVA254 NOM on the stability of oxygen NBs were more significant than other conditions. The half-lives of oxygen NBs under various conditions follow the order Ca2+ < Na+ < pH 3 < high SUVA254 NOM < pH 5 < 30 °C. Oxygen NBs were more stable in softwater than hardwater. Oxygen NBs were relatively stable for 3 days regardless of pH. For a longer storage period, oxygen NBs disappeared faster at pH 3 than at high pH. High SUVA254 NOM destabilized NBs more than low SUVA254 NOM, indicating the impact of hydrophobicity on the NB stability. The temperature effect on the NB stability was negligible for a short storage time, while higher temperature destabilized oxygen NBs for a longer storage time. One of the main disappearance pathway of oxygen NBs in water was found to be coalescing, rising, and leaving the container, which would be promoted greatly by cations, low pH and NOM with high aromaticity. The formation of hydroxyl radical in NB solutions was detected at pH 3 by a florescent probe molecule. When oxygen NBs are released in water bodies, high calcium, high SUVA254 NOM, and low pH would significantly reduce the availability of NBs and their residence time in freshwater.

A novel microbubble platform for cancer immunotherapy

The innate immune sensor cyclic GMP–AMP synthase–stimulator of interferon genes (cGAS-STING) has recently emerged as a potential therapeutic target to boost antitumor immune responses. However, STING is a cytoplasmic protein, and its natural activator cGAMP is a negatively charged dinucleotide that is difficult to deliver intracellularly. We have developed a new platform called Microbubble-assisted UltraSound (US)-guided Immunotherapy of Cancer (MUSIC) to activate STING with spatio-temporal control to treat cancer. MUSIC showed greater STING activation compared to cGAMP alone in vitro. In murine models, MUSIC showed dramatic tumor growth inhibition and increased survival in both syngeneic breast cancer models. The absence of antitumor immune responses in STING-/- mice shows that MUSIC action is STING-dependent. Furthermore, 6/10 MUSIC-treated mice were tumor-free versus 2/10 cGAMP-treated mice. All the rechallenged MUSIC-treated mice remained tumor-free 30 days after rechallenge. MUSIC also resulted in a 7-fold decrease in metastatic burden when compared to cGAMP alone. In summary, MUSIC showed efficient STING activation invitro. In addition, local MUSIC treatment of primary tumors produced systemic antitumor immune responses in vivo as well as anticancer immune memory preventing tumor growth upon rechallenge. We are now exploring the use of nanobubbles for systemic administration. [Work supported by CPRIT Grants RR150010 and RP190233. R.F.M. is a CPRIT Established Investigator.]

Sustainability and feasibility assessments of nanobubble aeration technology in economic-socio environment of Penaeus vannamei shrimp farming

Penaeus vannamei shrimp farming in Indonesia is faced with several challenges in the environmental, economic, and social aspects. Therefore, this study aims to assess the benefits of novel nanobubble aeration systems for the ecosystem, businesses, and communities. This is an experimental study conducted by comparing P. vannamei post larva 10 reared at a density of 2000 inds./L in a pond treated with nanobubble and without treatments (control). Furthermore, the Net Present Value (NPV) and payback period were calculated to assess the economic feasibility of nanobubble, while community interviews were used for the social sectors. Based on the results, environmental wastes of shrimp farming in form of total ammonia nitrogen (TAN) were reduced by 9% from 2.58 mg/l (95%CI: 0,91, 4,25) in control compared to 2.35 mg/l (95%CI: 0,86, 3,84) in treatment. Furthermore, the revenues from post larva sales for five years and nanobubble investment costs showed that the estimated NPV was IDR 64,824,374 with a payback period of 1.7 years. The interviews on traditional shrimp farming showed that 61.1% to 72.2% of community members agreed on the use of nanobubble aeration to support livelihoods. Therefore, the use of nanobubbles is feasible to support sustainable P. vannamei farming.

Nanobubbles as corrosion inhibitor in acidic geothermal fluid

Metallic corrosion is a major issue that leads to an efficiency loss and eventual failure of the system in geothermal power plants. Despite the growing understanding of mechanisms of corrosion, inhibiting steel corrosion in the acidic geothermal fluids, remains to present formidable challenges due to its intrinsic physicochemical complexity. Here, we study the use of nanobubbles as a possible corrosion inhibitor by testing alteration of the low-carbon steel plates immersed in acidic geothermal water with continuously injected air-nanobubbles. Nanobubbles have been used in a broad range of areas as they are eco-friendly, low-cost, easy-to-use and high-functional materials. We, for the first time to our knowledge, found that air-nanobubbles could inhibit steel corrosion, with inhibition efficiency of up to 50 % in the studied acidic geothermal fluid. Air-nanobubbles could act as a nanoscopic coating material in the acidic geothermal fluid, through generating a bubble mattress and/or promoting nucleation and aggregation of a very small quantity of silica precipitation on the surface of steel plates. Our finding suggests that nanobubbles can inhibit steel corrosion in various chemically different geothermal fluids, highlighting the physicochemical significance of nanobubbles as the coating material for inhibiting metal degradation in the geothermal infrastructures.

Effects of nanobubbles in column flotation of Chinese sub-bituminous coal

ABSTRACT Effects of nanobubbles on fine coal column flotation and underlying mechanisms have been investigated under different operating parameters including frother dosage, collector dosage, feed flow rate, air flow rate and wash water flow rate with a Chinese sub-bituminous coal sample. Experimental results show that the use of nanobubbles significantly improved the column flotation efficiency with fine coal particles. The collector dosage was reduced by almost one half in the presence of nanobubbles as a result of nanobubbles playing a role as a secondary collector and a similar reduction in the frother dosage was observed due to distinctly different mechanisms of nanobubble generation as compared to traditional bubble formation methods. Nanobubbles generated based on the hydrodynamic cavitation mechanism also reduced required air dosage and improved carrying capacity. The aggregation effect of fine coal particles caused by the preferential formation of nanobubbles on the surface of hydrophobic coal particles in the flotation system improves the rate of mineralization of bubbles. The flotation efficiency enhancement by nanobubbles is a result of multiple benefits to flotation processes brought by nanobubbles that form directly on the surface of coal particles.

Development and characterization of nanobubbles containing paclitaxel and survivin inhibitor YM155 against lung cancer

Lung cancer remains 23% of cancer-related death worldwide, ranking on first place for men and second place for women. Almost each cancer type has a great deal in common, overexpression of the apoptosis inhibitor survivin. Chemotherapy with anticancer drugs is leading to side effects. Drug targeting by the use of nanobubbles is a useful strategy to reduce side effects. Nanobubbles in cancer are one of the most investigated carriers in the last years. The size of nanobubbles (1–500 nm) is bigger than the pore size of healthy tissues, but smaller than the pores of cancer tissues. Thus, it is not possible for the drug to leave the blood stream and enter the tissue, but it can enter the cancer tissue through the pores, where it can accumulate. Therefore, the probability of undesired side effects decreases. For that reason, the development of nanobubbles containing paclitaxel and survivin inhibitor sepantronium bromide (YM155) were carried out. Characterization studies in terms of particle size, size distribution, zeta potential and morphology, and investigation of their effects on lung cancer cells were performed. To the best of our knowledge, there is no information in the literature about combining paclitaxel and YM155 loaded nanobubbles with ultrasound exposure.

Nanobubble Technologies Offer Opportunities To Improve Water Treatment.

Since first hypothesizing the existence of nanobubbles (NBs) in 1994, the empirical study of NB properties and commercialization of NB generators have rapidly evolved. NBs are stable spherical packages of gas within liquid and are operationally defined as having diameters less than 1000 nm, though they are typically in the range of 100 nm in one dimension. While theories still lack the ability to explain empirical evidence for formation of stable NBs in water, numerous NB applications have emerged in different fields, including water and wastewater purification where NBs offer the potential to replace or improve efficiency of current treatment processes. The United Nations identifies access to safe drinking water as a human right, and municipal and industrial wastewaters require purification before they enter water bodies. These protections require treatment technologies to remove naturally occurring (e.g., arsenic, chromium, fluoride, manganese, radionuclides, salts, selenium, natural organic matter, algal toxins), or anthropogenic (e.g., nitrate, phosphate, solvents, fuel additives, pharmaceuticals) chemicals and particles (e.g., virus, bacteria, oocysts, clays) that cause toxicity or aesthetic problems to make rivers, lakes, seawater, groundwater, or wastewater suitable for beneficial use or reuse in complex and evolving urban and rural water systems. NBs raise opportunities to improve current or enable new technologies for producing fewer byproducts and achieving safer water. This account explores the potential to exploit the unique properties of NBs for improving water treatment by answering key questions and proposing research opportunities regarding (1) observational versus theoretical existence of NBs, (2) ability of NBs to improve gas transfer into water or influence gas trapped on particle surfaces, (3) ability to produce quasi-stable reactive oxygen species (ROS) on the surface of NBs to oxidize pollutants and pathogens in water, (4) ability to improve particle aggregation through intraparticle NB bridging, and (5) ability to mitigate fouling on surfaces. We conclude with key insights and knowledge gaps requiring research to advance the use of NBs for water purification. Among the highest priorities is to develop techniques that measure NB size and surface properties in complex drinking and wastewater chemistries, which contain salts, organics, and a wide variety of inorganic and organic colloids. In the authors' opinion, ROS production by NB may hold the greatest promise for usage in water treatment because it allows movement away from chemical-based oxidants (chlorine, ozone) that are costly, dangerous to handle, and produce harmful byproducts while helping achieve important treatment goals (e.g., destruction of organic pollutants, pathogens, biofilms). Because of the low chemical requirements to form NBs, NB technologies could be distributed throughout rapidly changing and increasingly decentralized water treatment systems in both developed and developing countries.

Effect of frother type and operational parameters on nano bubble flotation of quartz coarse particles

In this work, the effects of the types of frother (MIBC, pine oil, and A65) and operational parameters (impeller speed and air flow rate) on the flotation of quartz coarse particles was investigated using nano bubbles (NBs). Quartz particles of the size of -425+106 mm and three types of frother were used for the flotation experiments. Also the impeller speed was 600 to 1300 rpm, and the air flow rates were 30 and 60 L/h. In the absence of NBs, the maximum recovery was achieved with the pine oil frother, an impeller speed of 1000 rpm, and an air flow rate of 60 L/h. In the presence of NBs, the maximum recovery was achieved using pine oil at an impeller speed of 900 rpm and an air flow rate of 30 L/h. However, increasing the recovery in the presence of NBs, compared to the absence of NBs for MIBC, was more than the other two frothers, and the recovery using this frother to increase up to 25% but using pine oil, the recovery increased up to 23%. The lowest recovery in the presence of NBs was obtained using A65. Also the use of NBs increased recovery in all the three fractions compared to the absence of NBs but the presence of NBs increased the recovery of particles with size of -212+106 mm more than the particle size in the ranges of -300+212 and -425+300 mm.

Investigation of Effects of Nanobubbles on Phosphate Ore Flotation

Phosphorous is vital for life, including plants, animals, and human beings and it is an essential component in agricultural fertilizers and phosphorous-based chemicals. Phosphate ores, mainly in the form of apatite and collophanite, are non-renewable natural resources of phosphorus. Froth flotation has been used in the phosphate industry for more than half a century as the primary technique for upgrading phosphate. Nevertheless, flotation does not produce satisfactory performance for phosphate beneficiation in many cases, especially for very fine and coarse phosphate particles. This study was performed with an aim to develop a nanobubble enhanced flotation process to enhance phosphate flotation efficiency. A specially designed flotation column featured with a nanobubble generator and a conventional bubble generator was employed to assess the effects of nanobubbles on the phosphate ore flotation performance under different operating conditions. Flotation process parameters investigated include feed flow rate, dosage of collector, dosage of frother, flotation time, etc. The flotation results have shown that use of nanobubbles increased P 2 O 5 recovery by up to 30% for a given Acid Insoluble (A.I.) rejection, depending on phosphate concentrate grade. Nanobubbles reduced the collector and frother dosage by about 50% and also increased flotation kinetics. The improved flotation performance can be attributed to increased collection efficiency and surface hydrophobicity in the presence of nanobubbles.

Optimization of Nanobubble-Assisted Bunker Oil Flotation from Oil-Wet Sand via Response Surface Methodology (RSM)

Flotation technology is an effective method for the separation of oil from sand via gas-liquid-solid system. The mechanism of flotation lies in the generation of gas bubble that attaches itself to the hydrophobic particles. Therefore, one of the main parameters which could affect the efficiency of flotation is the bubble size distribution. This research aims to investigate the efficiency of nanobubbles (NBs) in the flotation process to remove high density bunker oil from oil/sand slurry in a laboratory-scale flotation cell. Experiments were carried out using NBs (approximate diameter of 200 nm) generated via ultrasonication for the flotation studies. In this investigation, four different variables including amplitude (sonication power), pH, duration of sonication (min) and input flowrate of NBs (ml/s) were studied. The second order response function was used for obtaining flotation efficiency, and was further optimized using response surface methodology (RSM) to maximize flotation efficiency within the experimentally studied range. The optimum parameters were found to be, 70% amplitude, pH 12, 10 min of flotation and an input flowrate of 57 ml/s to achieve the predicted maximum flotation efficiency of 19.83%. This was in agreement to the experimental results which show an optimum flotation efficiency of 19.98%. The test results indicated that the use of NBs alone provided unsatisfactory flotation. Even though NBs (larger surface area) are expected to increase the bubble-particle attachment and decrease the detachment probabilities, the low buoyancy/low rising velocity of NBs prevents efficient flotation despite the advantages they have. Future studies would include the optimization of bubble size to improve the flotation efficiency

Effect of nanobubbles on the flotation of different sizes of coal particle

Froth flotation is the most widely used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating idtrafine coal and coarse coal particles. Our previous fundamental test residts demonstrated that cavitation-generated nanobubbles around 700 tun in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubbles on the flotation performance of different particle size fractions of coal was investigated using a bank of 10-L flotation cells, a specially designed 50-nun inside diameter column and a 152-nun inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during the froth flotation process improved flotation efficiency. The use of nanobubbles in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.

Nanobubble generation and its applications in froth flotation (part IV): mechanical cells and specially designed column flotation of coal

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.

Improved Cleaning of Hydrophilic Protein-Coated Surfaces using the Combination of Nanobubbles and SDS

The use of nanobubbles, the common surfactant sodium dodecyl sulfate (SDS), and nanobubbles in combination with SDS as cleaning agents to remove lysozyme from the solid-liquid interface has been investigated using a quartz crystal microbalance on both hydrophobic and hydrophilic surfaces. On the hydrophobic surface, significant amounts of protein remained on the surface after 10 cycles of nanobubble treatment for 10 s periods in phosphate buffer. The cleaning efficiency of SDS was far superior and was shown to remove approximately 90% of the protein. The use of nanobubbles in combination with SDS failed to improve the cleaning efficiency further. On the other hand, lysozyme on the hydrophilic surface cannot be removed effectively by either 10 cycles of cleaning with nanobubbles or 10 cycles of cleaning with SDS. Nevertheless, the protein can be removed completely after 6 cycles of cleaning with nanobubbles in combination with SDS.