Micro-nano Bubbles Research Articles

Indirect catalytic oxidation of multi-pollutants in diesel exhaust by ozone/micro-nano bubbles system

ABSTRACT Wet oxidation absorption is an efficient and promising method of exhaust gas treatment. When the micro-nano bubbles collapse, they can generate hydroxyl radicals with strong oxidising ability, which can oxidise a variety of pollutants in diesel exhaust. Ozone has strong oxidising properties, and the coupling of ozone and micro-nano bubbles can improve the oxidation and removal effects of polluted gases. In this study, the ozone micro-nano bubbles system was used to oxidise NO x , SO2, and CO to gases that were more readily dissolved in water, such as NO2, SO3, and CO2, and the gases were removed through the absorbent solution. The effects of surfactant, catalyst, urea, pH value, and salinity on the removal efficiency of NO x , SO2, and CO from diesel exhaust were investigated. Through experiments, it was found that the removal efficiency of pollutants was enhanced and then weakened with the increasing concentrations of surfactants, catalysts, and salinity, and continued to decrease with increasing concentrations of urea. When the pH value was < 7, the removal efficiency increased first and then weakened with the increase of the pH value. When the pH value was > 7, it mainly depended on the absorption of acid gas by the alkali solution. Under optimal conditions, the removal efficiencies were 86.3% for NO, 92.1% for SO2, and 65.4% for CO. This study could provide important theoretical support for the industrial application of this technology.

Photo-sterilization of groundwater by tellurium and enhancement by micro/nano bubbles

In rural areas where low-temperature groundwater is used as a drinking water source, cost-effective sterilization techniques are needed to prevent groundwater consumers from the disease risks triggered by pathogenic microorganisms like Escherichia coli and fungal spores. In this study, micro/nano bubbles (MNBs) coupled with the tellurium (Te)-based catalysts were used to considerably enhance the solar disinfection (SODIS) efficiency while overcoming the intrinsic defects of SODIS, particularly in low-temperature. Sterilization tests showed that 6.5 log10 cfu/mL of E. coli K-12 and 4.0 log10 cfu/mL of Aspergillus niger spores were completely inactivated within 5 min while applying this novel process for disinfection of raw groundwater, even in low-temperature. The underlying mechanisms of the extraordinary sterilization efficiency were revealed through comprehensive characterization of the catalysts and the physiological changes of the microorganisms. The localized surface plasmon resonance (LSPR) effect of the Te catalysts was identified to take advantage of photothermal synergism to achieve cell death. The integration of MNBs with the facet-engineered Te catalysts improved the photothermal catalytic effect and extracellular electron transfer, which substantially strengthened disinfection efficiency. This study provides a targeted solution into microbial inactivation in groundwater and emphasizes a cost-effective groundwater sterilization process.

Brief Discussion on the Application of the New Melting-Deicing Device (MDD) on the Flap Gate of the Yitong River

In order to solve the winter operation problem of the flap gate of the Yitong River in Jilin Province, 4 sets of new Melting-Deicing Devices(MDD) were arranged in front of the flat gate, and the prototype observation research were carried out as well. The analysis results showed that MDD mixed compressed air into the water body during its work so that micro-nano bubbles were formed, and then the water body mixed with bubbles was pushed out and diffused horizontally under the drive of the motor, which had a high disturbance ability to the water body, and could realize the heat exchange between the bottom water body and the surface water body, thereby having an ice-thawing effect on the frozen layer, and effectively reducing the generation rate of ice nucleus in the water for the unfrozen water body, thus avoiding the generation of ice flowers and preventing the freezing of the water surface.

Training on Making NPK Liquid Organic Fertilizer With The Application of Econobiotechnology

Policy reforms and research on agricultural ecology need to be intensified to reduce land degradation and the massive ecological and chemical impacts of soil chemical pollution. This is related to the increase in population that requires clothing, food, and welfare. Furthermore, although there has been a shift toward a form of agriculture with high-added value. This problem must be solved by diversifying efforts, applying ecology to agricultural cultivation land, and making breakthroughs in making organic fertilizers with various sources and environmentally friendly ways. This is rational and can be done by involving the industry, universities, and farmer groups who are smart and productive. Regarding farming diversification, The results obtained are by the solutions offered, farmers can make liquid organic fertilizers by utilizing water measuring 200 nm to 10 m of Micro-Nano-Bubbles (MNBs). This is following the concept and is the application of Econobiotechnology. Knowledge before participating in the training in making fertilizers Organic Liquid is 74%, while knowledge after attending training on making Liquid Organic Fertilizer is 91%. The interest in learning and making Liquid Organic Fertilizer is 40%.

Advanced Simulation of Quartz Flotation Using Micro-Nanobubbles by Hybrid Serving of Historical Data (HD) and Deep Learning (DL) Methods

The present study investigates the optimization and advanced simulation of the flotation process of coarse particles (–425 + 106) using micro-nanobubbles (MNBs). For this purpose, flotation experiments in the presence and absence of MNBs were performed on coarse quartz particles, and the results were statistically analyzed. Methyl isobutyl carbinol (MIBC) was employed as a frother for generating MNBs through hydrodynamic cavitation. The significance of the operating variables, including impeller speed, air flow rate, together with the bubble size, and particle size on the flotation recovery was assessed using historical data (HD) design and analysis of variance (ANOVA). The correlation between the flotation parameters and process response in the presence and absence of MNBs was modeled using hybrid convolutional neural networks (CNNs) and recurrent neural networks (RNNs) as the deep learning (DL) frameworks to automatically extract features from input data using a CNN as the base layer. The ANOVA results indicated that all variables affect process responses statistically and meaningfully. Significant interactions were found between air flow rate and particle size as well as impeller speed and MNB size. It was found that a CNN-RNN model could finally be used to model the process based on the intelligent simulation results. Based on Pearson correlation coefficients (PCCs), it was evident that particle size had a strong linear relationship with recovery. However, Shapley additive explanations (SHAP) was considerably more accurate in predicting relationships than Pearson correlations, even though the model outputs agreed well.

Full-Scale O3/Micro-Nano Bubbles System Based Advanced Oxidation as Alternative Tertiary Treatment in WWTP Effluents

Wastewater treatment plant effluents can be an important source of contamination in agricultural reuse practices, as pharmaceuticals are poorly degraded by conventional treatments and can enter crops, thereby becoming a toxicological risk. Therefore, advanced tertiary treatments are required. Ozone (O3) is a promising alternative due to its capacity to degrade pharmaceutical compounds, together with its disinfecting power. However, mass transfer from the gas to the liquid phase can be a limiting step. A novel alternative for increased ozone efficiency is the combination of micro-nano bubbles (MNBs). However, this is still a fairly unknown method, and there are also many uncertainties regarding their implementation in large-scale systems. In this work, a combined O3/MNBs full-scale system was installed in a WWTP to evaluate the removal efficiency of 12 pharmaceuticals, including COVID-19-related compounds. The results clearly showed that the use of MNBs had a significantly positive contribution to the effects of ozone, reducing energy costs with respect to conventional O3 processes. Workflow and ozone production were key factors for optimizing the system, with the highest efficiencies achieved at 2000 L/h and 15.9 gO3/h, resulting in high agronomic water quality effluents. A first estimation of the transformation products generated was described, jointly with the energy costs required.

Cyclic solubilization and release of polycyclic aromatic hydrocarbons (PAHs) using gemini photosensitive surfactant combined with micro-nano bubbles: a promising enhancement technology for groundwater remediation

Polycyclic aromatic hydrocarbons (PAHs) have posed serious risks to the groundwater environment. Surfactant-enhanced remediation (SER) is a promising strategy, as it can increase the solubilization efficiency of PAHs contaminants. However, this technology is still hampered due to low efficiency and high cost for the separation of pollutants after solubilization. Through the combination of micro-nano bubbles (MNBs) with a gemini photosensitive surfactant (N1, N2-bis[4-[4-[(4-butylphenyl) azo] phenoxy] butyl]-N1, N2-tetramethylethane-1,2-diammonium bromide, AzoPBT), herein we present a significantly enhanced efficiency of phenanthrene (Phe) solubilization and surfactant cycling. Notably, the presence of MNBs was conducive to the dissolution and release of Phe by reducing the CMC and γ of trans-AzoPBT (from 0.52 mmol/L and 28.94 mN·m−1 to 0.39 mmol/L and 27.88 mN·m−1) and increasing the difference of interfacial properties between trans and cis-AzoPBT, which was owing to the electrostatic interaction. Groundwater chemical parameters, i.e., ions, pH and organic matter would affect the solubilization ability of trans-AzoPBT. Mg2+ and Ca2+ inhibited the solubilization while SO42− promoted the solubilization, depending on their radius, electronic quantity and solution pH. A change in the HA level up to 8 mg/L had a negatively effect on the solubilization ability. High release rate (69.39 %) of cis-AzoPBT for Phe and high recovery rate (89.37 %) for tans-AzoPBT were obtained in the AzoPBT/MNBs mixed aqueous solution. Compared to MNBs combined with conventional cationic surfactants, AzoPBT/MNBs mixed aqueous solution exhibited better synergistic solubilization performance, and the apparent solubility of Phe increased from 26.74 % to 31.61 %. Overall, this study demonstrates the enhanced solubilization of PAHs by photosensitive surfactants combined with MNBs, which provides valuable insights of the effective utilization of surfactants in the remediation of PAHs-contaminated groundwater with SER technology.

Develop an optimal daily washing care for technical jacket by balancing washing efficiency and functional degradation

In order to reduce the functional degradation caused by improper daily washing-care and prolong the service life of technical jacket, the relationship between the daily washing conditions and functional degradation in the wearing performance of technical jacket (waterproof, windproof, warmth retention) was quantitatively investigated with the help of hydrostatic pressure, surface contact angle, air permeability, warmth retention, and scanning electron microscopy (SEM) of technical jacket after different daily washing conditions. Results showed that no matter what kind of washing modes, washing parameters, type and dosage of detergent, the wearing performance of technical jacket after washing were subjected to decrease compared with pre-washing. Additionally, it was also found that the effects of washing modes, type of detergents and washing parameters on the wearing performance of the technical jacket were significant, instead of the dosage of detergents. This indicates it was possible ways to minimize functional degradation by setting optimal washing conditions (washing parameters, washing mode, types and dosage of detergent). Balancing considerations of functional degradation and washing efficiency, the washing combination of mechanical agitation + micro-nano bubbles), type of detergent (neutral liquid detergent), dosage of detergent (3 g/L), water temperature (20°C), main washing bath ratio (1:10), main washing speed (15 rpm), main washing time (20 min), rinsing speed (30 rpm), rinsing cycles (2), belonged to the optimal washing combination in this study of washing condition. The results were of practical significance to guide manufacturers of washing machine to develop optimal daily washing produce for outdoor clothing, especially technical jacket.

A metal-organic framework regulated graphdiyne-based electrochemiluminescence sensor with a electrocatalytic self-acceleration effect for the detection of di-(2-ethylhexyl) phthalate.

In this work, a super-sensitive electrochemiluminescence (ECL) aptamer sensor was constructed using a multiple signal amplification strategy to realize ultra-sensitive detection of di-(2-ethylhexyl) phthalate (DEHP). The incorporation of a highly efficient electrocatalytic metal-organic framework (NH2-Zr-MOF) and graphdiyne (GDY) composite has significantly enhanced the overall electrochemically active surface area, facilitating electron transfer during the entire electrochemical reaction process, and the large number of pores in graphdiyne and NH2-Zr-MOF limited a series of redox reactions within a certain range. This resulted in the generation of a greater number of SO4˙- radicals, thereby boosting the ECL intensity of the GDY in the K2S2O8 system. To increase the performance of the sensor even further, sodium ascorbate (NaAsc) as an accelerator was added to the co-reactant system. Additionally, nitrogen micro-nano bubbles with higher stability and stronger mass transfer have been introduced into the ECL system for the first time. Based on these, the aptamer as the recognition element realized the ultra-sensitive detection of DEHP in the linear range of 1.0 × 10-12 to 1.0 × 10-4 mg mL-1 with the limit of detection (LOD) of 2.43 × 10-13 mg mL-1. In summary, we have utilized the electrocatalytic activity of the porous MOF and the reducing capability of sodium ascorbate to enhance the ECL emission of GDY, which has been successfully applied to the detection of DEHP in water samples.

Effect of micro-nanobubbles with different gas sources on the growth and metabolism of chemoautotrophic microorganisms

Micro-nanobubbles (MNBs) have excellent stability and a long retention time in water; their properties vary greatly with different gas sources. In this study, the effects of MNBs with different gas sources, including CO2, N2, O2, and air, on growth and metabolism of the chemoautotrophic strain Sinomicrobium oceani WH-15, which fixes CO2 via the Calvin-Benson-Bassham pathway, were evaluated. MNBs at low concentrations (5–20 %) could promote microbial growth with a maximum increase of 55 % (air MNBs) whereas MNBs at high concentrations (20–50 %) inhibited microbial growth with a maximum decrease of − 79 % (CO2 MNBs). The influence of MNBs was achieved through indirect and direct roles. MNBs with different gas sources had different effects on physical and chemical factors (pH, dissolved oxygen, oxidation-reduction potential, and conductivity) of microbial culture medium. MNBs at high concentration led to an increased intracellular antioxidant capacity of microorganisms and a decrease in the intracellular reduced glutathione, which may be due to exogenous reactive oxygen species produced by MNBs. MNBs could bring reducing power to microorganisms and reduce their metabolic output of extracellular polysaccharides. Our results demonstrated that MNBs with different gas sources improved microbial CO2 fixation through different mechanisms.

A novel method for the separation of saponin from soybean meal by colloidal gas aphrons: optimization based on response surface methodology

Natural surfactants, such as soy saponins, are rich in triterpenoid saponins, which have significant biological activities and are used in different applications, such as cosmetics, food, and pharmaceutical industries. In this research, it was used colloidal gas aphrons (CGAs) as a green and cost-effective method to concentrate soy saponin from soybean meal extract. The production of micro-nano bubbles, in conjunction with the investigation of the effect of different chemical and process variables, significantly impacted the purity and recovery of saponins in this method. The response surface methodology (RSM) was employed to optimize the process. The purity and recovery percentage of saponins were found to be 75.12 and 25.87 in optimal conditions, respectively. Furthermore, when the maximum value for both responses was selected, the purity and recovery reached 57.61% and 71.94%, respectively. Eventually, the results indicate that this method is technically promising, straightforward, and cost-effective in separating saponins for various applications.

Effect of pore size distribution and colloidal fines of porous media on the transport behavior of micro-nano-bubbles

The key of successful application of micro-nano-bubbles (MNBs) for groundwater remediation is understanding the transport characteristics of MNBs in porous media. The effect of pore size distribution and colloidal fines on transport behavior of MNBs in saturated porous media was studied in this research. At first, the diameter of MNBs and pore distribution of porous media were measured. Then, the hydraulic conductivities of ten different kinds of porous media were tested by distilled water and MNBs solution. Finally, one-dimensional column transport experiments of MNBs in saturated porous media were conducted. The test results showed that the diameter of MNBs was mainly distributed in 61–172 nm and 1.635–3.270 µm. The size of pore in glass beads was bigger than the diameter of MNBs, while the size of most pores in mixture of silt and sand or kaolinite was smaller than the diameter of MNBs. When transporting in porous media, MNBs had no effect on the hydraulic conductivity of coarse, medium or fine glass beads. However, MNBs had detrimental effect on hydraulic conductivity of the mixture of silt and quartz sand or kaolinite. Advection-dispersion theory was suitable for fitting the breakthrough curve of MNBs. The values of retardation factor (R) and pseudo first order rate coefficients for attachment (μ) were largest in the mixtures of silt and kaolinite, followed by silt as well as mixtures of silt and quartz sand, and smallest in glass beads. The particle size of porous media, the relative size of MNBs and pores, and colloidal fines significantly affected the transport behavior of MNBs in porous media. Furthermore, the deformation and dissolution of MNBs as well as unfavorable surface interactions between sand particles and bubbles could promote the transport of MNBs in saturated porous media. Thus, MNBs injection and transport are expected to be effective in remediation of contaminated site composed of sand or fine-grained soil with few colloidal fines.

Boosting oxygen diffusion by micro-nano bubbles for highly-efficient H2O2 generation on air-calcining graphite felt

Electrochemical H2O2 generation via oxygen reduction has to face dissolved oxygen transfer limitation in aeration system. To mitigate this problem, we proposed to boost oxygen diffusion by micro-nano bubbles (MNBs) for highly-efficient H2O2 generation on air-calcining graphite felt (GF600). The oxygen transfer coefficient and rate of MNBs were 0.160 min−1 and 0.382 kg m−3 h−1, about 4 times and 5 times greater than those of conventional aeration, respectively. As a result, the GF600 electrode under MNBs aeration could produce 140.4 ± 1.6 mg L−1 H2O2 with an ultrahigh coulombic efficiency of 97.8 ± 0.9%, but only 47.9 ± 2.5 mg L−1 H2O2 with 65.9 ± 3.7% under conventional aeration. By increasing the potential on the GF600 electrode, the H2O2 production showed the first rising then descending trend with and the optimized potential of −0.6 V. Besides, during 5 cycles the H2O2 production of GF600 was stably ranged from 124.8 mg L‒1 to 145.2 mg L‒1 with high coulombic efficiency of 94.3%−97.8% under MNBs aeration. Thus, micro-nano bubbles could effectively solve O2 mass transfer limitation, paving a promising way for in-situ synthesis of H2O2.

Effects of aerated brackish water irrigation on growth of Lycium barbarum seedlings

The management of Lycium barbarum seedling has an important influence on its fruit yield and quality at mature stage. Pot experiments were conducted to investigate the effects of four water salinity levels (0.6 (fresh water), 1.5, 3.0 and 4.5 g/L) under non-aeration (O2 content of 8.5 mg/L) and aeration (15.0 mg/L) irrigation on soil enzyme activity and the physiological parameters and growth status of Lycium barbarum seedlings. The results showed that brackish water irrigation increased soil electrical conductivity by 1.8 – 5.8 times, inhibited soil enzyme activities by 12.1% – 52.0%, and decreased the net photosynthetic rate by 10.7% – 24.8%, transpiration rate by 24.3% – 27.3%, and plant water consumption by 0.9% – 18.0% compared with fresh water irrigation. Brackish water irrigation also significantly inhibited the growth of leaves, base stem, roots and biomass of Lycium barbarum seedlings. Compared with non-aeration irrigation, the micro-nano bubble aerated brackish water irrigation promoted the activities of urease and alkaline phosphatase by 0.5% – 33.0% and 4.4% – 9.0%, respectively, and increased net photosynthetic rate by 3.3% – 8.0%, plant transpiration rate by 0.1% – 25.3%, and water consumption by 0.7% – 5.0% under brackish water irrigation. It also promoted the growth of leaves, branches, base stem and roots, and increased the biomass accumulation of Lycium barbarum seedlings by 7.4% – 9.3%. The aerated water irrigation with micro-nano bubbles can alleviate the negative effects of salt stress on the growth of Lycium barbarum seedlings to varying degrees, so the salinity of irrigation water less than 3.0 g/L combining with the aerated disposal is suggested to be as an optional solution to the planting of Lycium barbarum seedlings in arid oasis regions.

A modelling approach to explore the optimum bubble size for micro-nanobubble aeration

Bubble aeration has been widely applied in water/wastewater treatment, however its low gas utilization rate results in high energy consumption. Application of micro-nanobubbles (MNB) has emerged as a process with the potential to significantly increase gas utilisation due to their high relative surface area and high gas-liquid mass transfer efficiency. In this study, we demonstrate through calibrated models that MNB of an optimum bubble size can shrink and burst at or below the water surface enabling (1) all encapsulated gas to thoroughly dissolve in water, and (2) the bursting of nanobubbles to potentially generate free radicals. Through the understanding of MNB dimensional characteristics and bubble behaviour in water, a dynamic model that integrated force balance (i.e. buoyancy force, gravity, drag force, Basset force and virtual mass force), and mass transfer was developed to describe the rising velocity and radius variation of MNB along its upward trajectory. Unlike for conventional millimetre-sized bubbles, intensive gas dissolution of MNBs led to radius reduction for small bubbles, while a large initial radius triggers bubble swelling. The initial water depth was also crucial, where greater depth could drive the potential for bubble shrinkage so that they were more liable to contract. For example, the optimum bubble size of air (42–194 μm) and oxygen (127–470 μm) MNB that could achieve complete gas transfer (100% gas utilisation) for a range of specific water depths (0.5–10 m) were calculated. The modelling results for microbubbles (10–530 μm) were well validated by the experimental data (R2>0.85). However, the validation of the modelling results for nanobubble (<1 μm) aeration requires further study due to a lack of available empirical data. In this study, the proposed model and analysis provided new insights into understanding bubble dynamics in water and offered fundamental guidance for practitioners looking to upgrade bubble aeration system.

Influence of Water with Oxygen and Ozone Micro-Nano Bubbles on Concrete Physical Properties.

In this study, the possibility of using mixing water containing O2 and O3 micro-nano bubbles (M-NBs) in concrete technology was investigated. In particular, the effect of micro-nano bubbles on the durability and frost resistance of concrete was analyzed. Concretes with two types of micro-nano bubbles were studied. The physical properties of both the modified concretes and the reference concrete were determined, i.e., specific and apparent density, porosity, weight absorption and coefficient of water absorption. Mechanical parameters based on compressive and flexural strength were tested after 14 and 28 days of curing. Concrete durability was determined on the basis of frost resistance and resistance to salt crystallization. The pore distribution in the cement matrix was determined based on porosimetry studies. The use of water with micro-nano bubbles of O2 and O3, among others, contributed to a reduction in the water absorption coefficient from 42.7% to 52.3%, in comparison to the reference concrete. The strength characterizing the concrete with O3 increased by 61% after 28 days, and the frost resistance after 150 F-T cycles increased by 2.4 times. Resistance to salt crystallization improved by 11% when water with O3 was used.

Co-coagulation of micro-nano bubbles (MNBs) for enhanced drinking water treatment: A study on the efficiency and mechanism of a novel cleaning process

MNBs (Micro-nano bubbles) are widely used in cleaning processes for environmental treatments, but few studies have examined the interaction of MNBs with coagulation. In this study, a novel process, i.e., MNBs-coagulation, was developed for enhanced drinking water treatment. The humic acid (HA) removal efficiency was used to evaluate the effectiveness of MNBs-coagulation for drinking water treatment. The hydrolysis component ratio of polymeric aluminum chloride (PACl) with and without MNBs, the complexation strength of HA and PACl, and flocculent functional group characterization were used to analyze the mechanism of the MNBs-coagulation process to enhance drinking water treatment. The results of a Jar test showed that the MNBs-coagulation process could improve the removal efficiency of HA (up to a 27.9% increase in DOC removal). In continuous-flow experiments to remove HA, MNBs-coagulation can increase the removal efficiency of UV254 by about 26.5% and with no significant change in turbidity. These results are attributed to the inherent hydroxyl radical generating properties of MNBs, the forced hydrolysis of PACl by MNBs to increase the Alc percentage, and the ability of MNBs to increase the complexation strength of HA with PACl. At the same time, the MNBs-coagulation process has a strong anti-interference ability, almost no interference from anions and cations such as Cl−, SO42− and Ca2+, and has a good performance in natural surface water. In summary, MNBs-coagulation has strong potential for practical applications to enhance the efficiency of drinking water treatment.

Generation of micro-nano bubbles by magneto induced internal heat for protecting cells from intermittent hypoxic damage

Micro-nano bubbles (MNBs) have attracted extensive attention in recent years due to their distinctive features and physiological activities. The particle size and size distribution of MNBs are important properties of their application. This study presented a green method, namely magneto internal heat bubble generation (MIHBG), for preparing magnetic MNBs based on the magnetically internal heating technology. The effects of the operation conditions on the properties of the generated MNBs were discussed. The results showed that the MNBs with good uniformity could be successfully prepared via MIHBG. Under the preferred conditions, the average size of the MNBs was 341.5 ± 18.2 nm with the polydispersity index (PDI) of 0.240 ± 0.027 and the zeta potential of − 42.4 ± 4.2 mV, respectively. The concentration of the generated MNBs could reach 1.5 × 109 particles/mL. Transmission electron microscopy (TEM) image demonstrated that the MNBs had a gas core with the superparamagnetic iron oxide nanoparticles (SPIONs) adsorbed on the surface. The mechanism of the MNBs generation process was explained by the classical nucleation theory. The good uniformity of the magnetic MNB samples benefited from the uniform hotspots formed by the SPIONs via the alternating magnetic field. In addition, the lipid-encapsulated Xenon bubbles (Xe-LBs) were prepared based on the MIHBG process to improve the stability of MNBs for the determination of protecting cells from intermittent hypoxic damage. MTT assay and TUNEL experiments indicated that the Xe-LBs played a significant role in protecting cells from intermittent hypoxic damage and inhibiting apoptosis of cells. These results revealed that the MIHBG process provided a novel way to prepare MNBs for potential applications such as protecting hypoxic neurons.

Effects of micro-/nanobubble on membrane antifouling performance and the mechanism insights

Membrane fouling problem has become a painful point of the membrane industry by causing huge energy consumption, material wastage and high cost. Micro-/nanobubbles (MNBs) as a novel strategy can effectively inhibit adhesion of pollutants during the treatment processes. The introduction of MNBs technology into membrane separation systems can be a worthy research topic for membrane antifouling. In the current study, it was found that the MNBs displayed significant effects on membrane permeability, rejection performance and especially antifouling performance. The experimental results confirmed that the MNBs effectively improved the permeability of membranes during the filtration processes. The separation tests showed that the MNBs can delay the flux attenuation and promote antifouling ability of 165.9%. Nanoparticle tracking analysis (NTA) results indicated that the pollutants tended to larger size particles which can be attributed to the agglomeration effect of MNBs. The MNBs served as a “gas bridge” between pollutants and membrane surface therefore can efficiently prevent the adhesions of pollutants. The MNBs technology with “gas bridge” effects can provides a novel strategy for membrane fouling control.

Effects of Different Concentrations of Micro-Nano Bubbles on Grain Yield and Nitrogen Absorption and Utilization of Double Cropping Rice in South China

Micro-nano bubble (MNB) irrigation can effectively improve the hypoxia stress caused by conventional irrigation and shows great potential in plant development, yield improvement, and saving of water and fertilizer, and has been recognized as a new and high-efficiency technology in crop planting. However, former research on MNB concentration had no clear segmentation, and other MNB concentrations can achieve better or worse effects. This remains to be further explored in order to explore the optimal concentration of MNBs for the yield and nitrogen absorption and utilization of the double cropping rice. With early rice Ganxin203 and late rice WufengyouT025 as the experimental cultivars, the effects of MNBs on growth, yield, and nitrogen absorption and utilization of the potted double cropping rice were analyzed by setting three concentrations of MNBs (LM, low concentration; MM, middle concentration; HM, high concentration), compared with the ordinary running water (CK). Compared with CK, grain yield of the early rice under the MNB treatment increased by 4.84~10.95% and the late rice increased by 6.10~14.31%. It was found that the higher the concentration of the MNBs, the higher the yield of the rice. This is due to that the MNBs improved the tiller-bearing rate, increased the SPAD and Pn values of the flag leaves in the whole growth period, slowed down the drop of the leaf SPAD and Pn from heading stage to maturity, increased the number of the adventitious roots, improved the α-NA oxidation of the root, and simultaneously promoted the nitrogen accumulation, absorption, and utilization. The HM treatment obtained the best benefits, and the effect of the MNBs on the late rice was better than the early rice.