Size Distribution Characteristics Research Articles

Pore Size Distribution and Fractal Characteristics of Deep Coal in the Daning-Jixian Block on the Eastern Margin of the Ordos Basin.

Important breakthroughs have recently been achieved in deep coalbed methane (CBM) exploration and development in regions such as the eastern margin of the Ordos Basin, China. Investigating the development characteristics of various-scale pores in deep coalbeds is of great significance for resource assessment and selection of favorable zones for CBM exploration. Herein, six deep coal samples were selected from the Shanxi and Taiyuan Formations in the Daning-Jixian block on the eastern margin of the Ordos Basin. Low-pressure CO2/N2 adsorption (LP-CO2/N2GA) and high-pressure mercury intrusion (HPMI) methods were employed to analyze pore volume, specific surface area, and pore size distribution, thereby evaluating the full-scale pore characteristics. Furthermore, the fractal dimension characteristics of deep coal rock pores were elucidated, revealing the influence of pore structure, burial depth, and coal composition. The results indicate that micropores in deep coal rocks have the highest volume and specific surface area proportions, while mesopores have the smallest volume proportion, and macropores make the least contribution to the total specific surface area. The V-S, Frenkel-Halsey-Hill, and Sierpinski models were suitable for calculating the fractal dimensions of micropores, mesopores, and macropores with LP-CO2GA, LP-N2GA, and HPMI experimental data, respectively. Other than the relatively smaller mesopore fractal dimension of samples 20-8 and 20-10, the micropore, mesopore, and macropore fractal dimensions successively increased in the other four samples. The comprehensive fractal dimension, which exhibited a decreasing trend with increasing pore volume and specific surface area, was negatively correlated with burial depth, mineral and moisture contents, and ash and volatile component yields, while it was positively correlated with vitrinite and fixed carbon contents.

Raindrop size distribution characteristics of pre-monsoon precipitation observed over eastern India

The knowledge of raindrop size distribution (DSD) is crucial for understanding the microphysical processes involved with the precipitation. Different empirical relationships established with DSD parameters, like radar reflectivity– rainfall rate (Z–R) relationships and shape–slope (μ–Ʌ) relationships, can progress the rainfall estimation algorithms and cloud modeling simulations. In the present study, long-term (2018–2021) measurements of a Laser Precipitation Monitor (LPM) disdrometer installed at the National Institute of Technology, Rourkela, India is used to investigate the DSD characteristics of pre-monsoon (March–May) rainfall. Along with the disdrometer data, auxiliary parameters like convective available potential energy (CAPE), total column water vapor (TCWV), vertical profiles of temperature and relative humidity from reanalysis data sets of ECMWF (European Centre for Medium-Range Weather Forecasts) fifth-generation reanalysis (ERA5) are also used in this study. Based on standardized rainfall anomaly, the pre-monsoon precipitation days are classified into strong, moderate, and weak rainy days, and they contributed to 58.69%, 32.7%, and 8.61% of total rainfall, respectively. The average DSD indicated noteworthy variations among strong, moderate, and weak rainy days with maximum (minimum) concentration of raindrops in strong (weak) rainy days. The mean value of rain rate (R), normalized intercept parameter (Nw), and mass-weighted mean diameter (Dm) is maximum during days of strong rainfall. Strong rainy days showed high-value CAPE, TCWV and vertical profile of relative humidity. The majority of R is contributed by moderate-sized raindrops with a significant difference in the Z–R and μ–Λ relationships among three types of rainy days.

Computational microfluidics of reactive transport processes with solid dissolution and self-induced multiphase flow

There are still many unclear mechanisms in the multiphase reactive flow with solid dissolution processes. In this study, the reactive transport processes coupled with solid dissolution and self-induced multiphase flow in three-dimensional (3D) structures with increasing complexity is studied by developing a 3D computational microfluidic method, which considers multiphase flow, interfacial mass transport, heterogeneous chemical reactions, and solid structure evolution. Solid dissolution diagram in a simple channel in the framework of multiphase flow is proposed, with six coupled multiphase flow and solid dissolution patterns identified and the transition between different patterns discussed. Then, multiphase reactive flow in a porous chip is further studied, and the interesting 3D phenomena are discovered, including enhanced solid dissolution in the middle and enriched bubble generation at the corner along the thickness direction. Considering the importance of reactive surface area, correlations of reactive surface area-porosity-saturation with different dissolution patterns are proposed based on the pore-scale results. Finally, the computational microfluidic model is extended to investigate the multiphase reactive flow in a 3D digital core. Different dissolution patterns are recognized using the local porosity evolution character, and the corresponding pore size distribution and bubble characteristics are deciphered. These findings advance understanding of multiphase reactive transport processes and contribute to improve continuum-scale reactive transport modeling.

Whole Process Analysis and Fate Behavior of Microplastics in Urban Wastewater Treatment Plants, Including their Occurrence Forms, Components, and Removal Efficiency

Microplastics are among the most difficult new pollutants to remove in wastewater treatment plants. In order to explore the occurrence form, size distribution, composition, removal efficiency, migration law, and fate behavior characteristics of microplastic particles in sewage plants, taking a sewage treatment plant in Hohhot as an example, a total of 17 sampling sites were set up. The LAS X software counted the shape, abundance, and size of microplastics and conducted a full-process analysis. The results showed that： fibrous microplastics had the highest abundance and widest distribution and were the main form of existence, accounting for 61.8% of the total abundance； the size of microplastics ranged mainly between 0 and 1.00 mm, and among the four sizes, the abundance of microplastics 0.25 to 0.50 mm in China was the highest, accounting for 32.9%. Among the eight types of plastic components detected, polyester substances （PET, PBT）, cellulose, and polypropylene （PP） were the main components, accounting for 25%, 21%, and 17%, respectively. The influent abundance of the sewage plant was （73 ±5） n·L-1, the effluent abundance was （14 ±2） n·L-1, and the overall removal rate was （80.8 ±12.1）%. Among the three treatment stages of the sewage plant, only the primary treatment played a role in removal, and the abundance of microplastics surged in the secondary treatment. Different structures playing a major role in the removal of microplastics were fine grids （49.2 ±7.4）% and secondary sedimentation tanks （92.4 ±13.9）%. Microplastics mainly existed in the form of fibers, fragments, and films. The proportion of fibers was approximately 70%, and the size of fragments was mainly concentrated between 0.50 and 5.00 mm. Most fragments were in the range of 5.00 mm, accounting for 50%, making them the main form apart from fibrous. The film-like size was mostly concentrated in the range of less than 0.50 mm, accounting for more than 10%. Therefore, improving the removal of small-sized fibrous and film-like microplastics and large-sized fragmented microplastic particles can effectively reduce the pollution risk of microplastics in the environment caused by sewage plant drainage.

Characterisation of urban aerosol size distribution by radiocarbon and PIXE analyses in a middle-European urban environment for source identification: a pilot study

This study, conducted in Debrecen, Hungary, aimed to analyse atmospheric particulate matter (APM or PM) through radiocarbon and PIXE analyses during the winter smog (23–25 January) and spring (15–18 May) seasons. The information presented in this pilot study aims to provide insight into the importance of utilising detailed characteristics of the mass size distributions of fossil carbon (ff) and contemporary carbon (fC) content. Additionally, it seeks to compare these characteristics with the size distributions of various elements to enable even more accurate PM source identification. In winter, APM concentrations were 86.27 μg/m3 (total), 17.07 μg/m3 (fC) and 10.4 μg/m3 (ff). In spring, these values changed to 29.5 μg/m3, 2.64 μg/m3 and 7.01 μg/m3, respectively. Notably, differences in mass size distribution patterns were observed between the two seasons, suggesting varied sources for contemporary carbon. Biomass burning emerged as a crucial source during the smog period, supported by similar MMAD (Mass Median Aerodynamic Diameter) values and a strong correlation (r = 0.95, p < 0.01) between potassium and fC. In spring, a significant change in the concentration and distribution of fC occurred, with a broad, coarse mode and a less prominent accumulation mode. Ff was found to have similar distributions as PM, with nearly the same MMADs, during both periods. Finally, a comprehensive comparison of modal characteristics identified specific sources for the various components, including biomass burning, vehicle exhaust, coal and oil combustion, vehicle non-exhaust, road dust, tyre abrasion, mineral dust and biogenic emission. This study showcases how using radiocarbon and PIXE analysis in size distribution data can enhance our understanding of the sources of PM and their effects on different size fractions of PM.

Top-Down Phenomenon Observed in the Outer Rainbands of Typhoon Maysak (2020): Insights from the Comparative Analysis of Cloud and Precipitation Microphysics with a Typical Precipitation Event in Northeast China

Abstract Cloud and precipitation microphysics in tropical cyclones (TCs) moving toward Northeast China may exhibit significant distinctions compared with the typical precipitation of this region. In this study, observations from ground-based particle size velocity (Parsivel) disdrometers in Liaoning Province, China, and cloud property data from the Himawari geostationary satellite were utilized to analyze the raindrop size distribution (DSD) characteristics and cloud vertical evolution associated with the outer rainbands of Typhoon Maysak (2020). A comparative analysis was conducted with a typical precipitation event in Northeast China induced by a cold vortex (cold-core low). Our findings reveal distinctive DSD characteristics related to the TC, where medium-sized raindrops dominate, with a smaller diameter but higher concentration in the TC case compared to the typical cold-vortex-induced precipitation case in Northeast China. Convective precipitation falls between maritime-like and continental-like patterns, leaning more toward continental convection. This varies significantly with TCs in Southeast China but is similar to that observed in coastal-front-like rainbands, suggesting extratropical influence. A detailed analysis of the vertical profile of cloud droplets shows a unique “top-down” phenomenon during the extratropical transition process of the TC, where the development of lower-level clouds follows that of upper-level clouds, inconsistent with previous studies and the case for comparison. Further investigation indicates the significant role of the intrusion of dry and cold air from upper levels and the presence of high humidity in low levels in driving this phenomenon. Our results will provide novel insights into cloud and precipitation microphysics associated with TCs in midlatitude regions.

Study on the Population Balance Dynamics Simulation of Grinding under Impact Crushing

During the grinding process, the crushing of minerals mainly depends on the impact action of the grinding medium. Based on the JK drop weight test data of quartz and pyrrhotite and the research results of their impact crushing characteristic parameters, this paper calculates the specific crushing energy (Ecs) of mineral samples subjected to impact in a ball mill using the grinding medium motion theory and then calculates the cumulative particle size distribution under screening under any mesh size using the JK drop weight test method. On this basis, the breakage distribution function of mineral samples is calculated, and a selection function is obtained based on grinding experiments. Finally, using Matlab programming and function-fitting mathematical methods, as well as a particle size population balance dynamics simulation of grinding, the particle size distribution characteristics of the grinding products of the two mineral samples in the mill that are only subjected to impact action are calculated. The results show that the selection function of quartz and pyrrhotite decreases overall with the prolongation of the grinding time, and the selection function of the coarse particle size changes more significantly than that of the fine particle size. At the same time, the selection function decreases with the decrease in feed particle size, and the smaller the feed particle size, the lower the probability of impact crushing. The Ecs values of quartz and pyrrhotite at each particle level in the mill are different, and the degree of mineral crushing is closely related to the impact energy, feed particle size, and mineral properties.

Evaluation of methane adsorption isotherms at ambient temperature on carbon materials from NLDFT pore size analysis derived from standard N2 and CO2 adsorption isotherms

In this paper, we attempt to estimate CH4 adsorption on carbon materials based on the pore size distribution (PSD) characteristics evaluated from standard nitrogen and carbon dioxide adsorption isotherms using the nonlocal density functional theory (2D-NLDFT), or more precisely, its two-dimensional version (2D-NLDFT). The PSDs of the carbons were calculated by the simultaneous fit of the NLDFT models to the corresponding N2 and CO2 adsorption data. This method is referred to in the literature as the dual gas analysis method which is implemented in SAIEUS software. Essential features of carbon PSDs affecting the shapes of methane adsorption isotherms measured at ambient temperature were identified as related to micro and mesopores carbon structure. We discuss how different micro and mesopore size ranges contribute to methane adsorption isotherms in the low and higher-pressure ranges. The results of the present study may serve as guidance for selecting and designing suitable carbon materials for practical applications such as PSA recovery of CH4 from its mixtures or for methane storage.

Effect of nanosilica on the hydrological properties of loess and the microscopic mechanism

Loess areas, such as the Loess Plateau, are characterized by a fragile ecological environment, high soil erosion, and frequent geological disasters due to the unique hydrological properties of loess (e.g., collapsibility and permeability). Therefore, the loess must be stabilized for use in engineering construction. Traditional stabilizers (lime, cement, and fly ash) cause environmental problems, such as soil salinization and greenhouse gas emissions. Therefore, this study investigated the effect of nanosilica on the hydrological properties of loess and the microscopic mechanism. Different nanosilica contents (0.2%, 0.4%, 0.8%, 1%, and 3%) were added to loess sample, and the particle size distribution, Atterberg limits, collapsibility, and soil water characteristics were analyzed. The results revealed the following. The addition of nanosilica changed the particle size distribution, liquid limit, plastic limit, and plasticity index of loess. After the addition of nanosilica with different contents, the loess collapsibility coefficient curve shifted downward, the soil water retention curve shifted upward, and the unsaturated permeability coefficient curve shifted downward. The pores between particles were filled, and the number of large and medium pores and the pore connectivity were lower after the nanosilica addition. The surface of the coarse particles adsorbed more fine particles, and a large number of micro-aggregates or clay aggregates were present in the pores between particles. In conclusion, the environmentally friendly material nanosilica can be used to improve the hydrological properties of loess, which is applicable to alleviating soil erosion and preventing geological disasters on the Loess Plateau.

Pore Size Distribution and Pore Connectivity Response Characteristics of Anthracite Injected with Carbon Dioxide in Different Phases

The adsorption of CO2 changes the pore content in coal. After CO2 adsorption, pore content in coal shows a trend of first increasing, then decreasing and then increasing. CO2 adsorption pressure, CO2 adsorption time and CO2-H2O slightly change the variation range of pore size, but the trend remains unchanged. For example, in the case of CO2 adsorption for 72 hours, the pore content of 2~10nm and &gt;700nm is generally increased, and the pore content of 10~700nm is significantly reduced. In the case of 144 hours of CO2 adsorption, the pore content of 2~20nm and &gt;700nm generally increased, and the pore content of 20~700nm significantly decreased. When water +CO2 was adsorbed for 144 hours, the pore content of 2~12nm and &gt;700nm generally increased, and the pore content of 12~700nm generally decreased. The coal samples show a certain lag of mercury removal before and after CO2, which indicates that there are some ineffective pores in the coal. The mercury removal efficiency of the coal sample after CO2 adsorption is generally lower than that of the dry sample, indicating that a large number of inefficiently connected pores are generated after CO2 adsorption. That is, CO2 does increase a large number of pores in coal, but the pores are mainly non-connected pores, that is, CO2 has a weak improvement in the connectivity of the pores in coal

Microstructure and damage characteristics of cement mortar with different aggregate sizes after cooling based on nuclear magnetic resonance technology

This article studies the effects of cooling methods and aggregate sizes (particle size: 0.63–1.25 mm, 1.25–2.5 mm, 2.5–5.0 mm, 5.0–10.0 mm) on the microscopic properties and damage characteristics of cement mortar specimens. After heating the specimens to 400 °C, air cooling (cooling in air as a whole, A), water cooling (cooling in water as a whole, W), and semi-water cooling (half in air and the other half in water, AW) cooling methods are applied. The T2 spectrum, magnetic resonance imaging (MRI), permeability and P-wave velocity of the specimens were tested by low-field nuclear magnetic resonance (NMR), pulse pore permeability tester and digital acoustic wave instrument, respectively. The effect of cooling method and aggregate size on pore size distribution and fractal characteristics, permeability and tortuosity, P wave and damage degree of cement mortar specimens were studied. The relationship between MRI pixel value and damage degree was deeply explored. The results show that the average permeability and MRI pixel value increase after high temperature, and the pore tortuosity decreases. The mass loss rate, the increase of the most probable pore size and the increase of the pore volume are negatively correlated with the aggregate size, and the permeability ratio, the decrease of the tortuosity and the damage degree are positively correlated with the aggregate size. At the same time, the influence of cooling method on mass loss rate, porosity and permeability from large to small is: A, AW, W, while the decrease rate of pore tortuosity from large to small is: AW, W, A. The most probable pore size and pore volume change most obviously after high temperature treatment of W and AW. In addition, with the increase of aggregate size, the fractal dimension increases under air cooling, and the U-shaped change with W2.5 particle size as the threshold decreases first and then increases under semi-water cooling. Finally, there is a good exponential relationship between the average ratio of MRI pixel values and the damage degree, and the damage degree of the sample can be obtained by the average ratio of MRI pixel values.

Experimental investigation on fractal mechanism and shear failure characteristics of cement mortar at different curing ages

In this paper, the NMR and direct shear tests were conducted successively on cement mortar specimens with different curing ages (7 days, 14 days and 28 days). The porosity, shear strength, shear stiffness and shear energy of cement mortar are measured and analyzed through interpreting the pore distribution patterns and their corresponding fractal dimensions. The cross-sections of shear surface were characterized into point cloud data via 3D laser scanning and quantified by three dimensionless parameters (the root mean square value of the first derivative, root mean square value and joint roughness coefficient). The grey relation analysis (GRA) method and principal component analysis (PCA) is employed to analyze the relationship between the pore structures (i.e., gel pores, transition pores, capillary pores and pores or cracks) and distribution and the fractal dimensions. The results indicate that the shear peak strength is linearly correlated with the joint roughness coefficient. Compared to the fractal characteristics of pore size (T2 spectra) and pore distribution (MRI), we demonstrated that there is a strong correlation between the peak shear strength and the fractal dimension of shear fracture surface, which suggests that the quantitative characterization of internal pores and shear strength variations in cement mortar specimens can be achieved through the numerical values of fractal dimensions.

Research on dust control technology and numerical simulation of conical guiding air curtain in fully mechanized excavation face

The dust pollution caused by the operation of fully mechanized heading face poses a serious threat to the safety production of operators and working face. To reduce dust concentration at the fully mechanized heading face, this study analyzed dust samples collected from various positions to understand the particle size distribution characteristics. Based on these findings, a conical diversion air conditioning (CDAC) device was designed to create a radial air curtain for dust control in the roadway cross-section. Computational Fluid Dynamics (CFD) was then employed to investigate the airflow and particle dynamics when the cone-shaped deflector was in closed and open states. The results show that in the fully mechanized heading face, the dust distribution in the working area of the roadheader driver is relatively dense, and the dust particles with particle size ≤ 8 μm account for a large proportion. When the CDAC device is deployed, the axial airflow in the roadway is changed into a rotating airflow along the roadway wall, and an air screen is established in the working area of the roadheader driver to block the outward diffusion of dust. When the pressure air outlet is arranged 30 m away from the tunneling head, the pressure air volume is set to 400 m3/min, and the CDAC device can better form the air curtain barrier to block the dust particles. It provides a new method for effectively controlling the dust concentration of the fully mechanized heading face and directly ensuring the health of the roadheader driver.

Size distribution of brake wear particulate matter based on a brake dynamometer investigation

A brake dynamometer has been modified to accurately study the concentration and size distribution of wear particles in different testing conditions. The test equipment was a charged low-pressure impactor ELPI+ from Dekati, Finland. 29 test conditions were defined based on speed, acceleration and initial brake temperature. Additionally, five different types of brake pads were selected for testing to provide a more comprehensive understanding of the particle size distribution characteristics of brake wear particles. The results showed that the mass of BWPs was unimodal in the range of 0.01–8.11 μm, with peak sizes at 2–5 μm or &amp;gt;8.11 μm, and particles of 0.5–3.0 μm accounted for an average of 49.09% of the total particulate mass, while particles with sizes of 3.0–8.11 μm accounted for an average of 49.72% of the total particulate mass. The number of particles emitted by abrasion had a bimodal distribution, with one in the nucleation mode and the other in the accumulation mode, with peak sizes of &amp;lt;10 nm and 1 μm, respectively; the nucleation mode particles accounted for an average of 60.11% of the total PN10, and the ultrafine particles accounted for an average of 82.15%.

Reformulation of white chocolate with soy- and coconut-based vegetable ingredients incorporating encapsulated cinnamon extract: investigation of physicochemical, antioxidant, and sensory properties

ABSTRACT White chocolate, which does not contain cocoa mass, is less healthy than dark and milk chocolate. Due to its milk content, white chocolate can also cause issues for those with lactose intolerance or dairy allergies. To overcome these problems, a study was conducted by adding highly antioxidant encapsulated cinnamon extract (ECE) to vegan white chocolate formulated with different levels of soy protein isolate (SPI) and coconut flour (CF). This study aimed to examine the chocolate’s total phenolics, flavonoids, antioxidant activity (IC₅₀), protein and fat content, particle size distribution, texture, color, melting point, and sensory characteristics. The results showed that the addition of SPI and CF had a significant impact on the properties of the white chocolate, except for hardness. Incorporating 2% (w/w), ECE significantly increased the total phenolics, flavonoids, and antioxidant activity. Total phenolics and flavonoids were positively correlated with antioxidant activity. Vegan white chocolate formulated with 27% SPI, 10% CF, and 2% ECE was acceptable to panelists, and thus, this product can be potentially consumed by lactose-intolerant and vegan consumers.

Engineering High-Performance Li Metal Batteries through Dual-Gradient Porous Cu-CuZn Host.

Porous copper (Cu) current collectors show promise in stabilizing Li metal anodes (LMAs). However, insufficient lithiophilicity of pure Cu and limited porosity in three-dimensional (3D) porous Cu structures led to an inefficient Li-Cu composite preparation and poor electrochemical performance of Li-Cu composite anodes. Herein, we propose a porous Cu-CuZn (DG-CCZ) host for Li composite anodes to tackle these issues. This architecture features a pore size distribution and lithiophilic-lithiophobic characteristics designed in a gradient distribution from the inside to the outside of the anode structure. This dual-gradient porous Cu-CuZn exhibits exceptional capillary wettability to molten Li and provides a high porosity of up to 66.05%. This design promotes preferential Li deposition in the interior of the porous structure during battery operation, effectively inhibiting Li dendrite formation. Consequently, all cell systems achieve significantly improved cycling stability, including Li half-cells, Li-Li symmetric cells, and Li-LFP full cells. When paired synergistically with the double-coated LiFePO4 cathode, the pouch cell configured with multiple electrodes demonstrates an impressive discharge capacity of 159.3 mAh g-1 at 1C. We believe this study can inspire the design of future 3D Li anodes with enhanced Li utilization efficiency and facilitate the development of future high-energy Li metal batteries.

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions.

Bubble dynamics significantly impact mass transfer and energy conversion in electrochemical gas evolution reactions. Micro-/nanostructured surfaces with extreme wettability have been employed as gas-evolving electrodes to promote bubble departure and decrease the bubble-induced overpotential. However, effects of the electrodes' wickability on the electrochemical reaction performances remain elusive. In this work, hydrogen evolution reaction (HER) performances are experimentally investigated using micropillar array electrodes with varying interpillar spacings, and effects of the electrodes' wettability, wickability as well as bubble adhesion are discussed. A deep learning-based object detection model was used to obtain bubble counts and bubble departure size distributions. We show that microstructures on the electrode have little effect on the total bubble counts and bubble size distribution characteristics at low current densities. At high current densities, however, micropillar array electrodes have much higher total bubble counts and smaller bubble departure sizes compared with the flat electrode. We also demonstrate that surface wettability is a critical factor influencing HER performances under low current densities, where bubbles exist in an isolated regime. Under high current densities, where bubbles are in an interacting regime, the wickability of the micropillar array electrodes emerges as a determining factor. This work elucidates the roles of surface wettability and wickability on enhancing electrochemical performances, providing guidelines for the optimal design of micro-/nanostructured electrodes in various gas evolution reactions.

Multifunctional amphoteric heteropolymer for chromium free sustainable leather process

AbstractThe post‐tanning process of leather making involves the of large quantities of auxiliary chemicals to enhance the functionalities of the leather. Hence, developing multifunctional polymers are essential to reduce the pollution load and enhance sustainability. Herein, we report the synthesis of multifunctional retanning and fatliquoring agent using a hydroxyethyl methacrylate (HEMA) monomer by modifying the hydroxyl group to carboxyl and long‐chain hydrocarbon along with quaternary ammonium monomer. The resulting polymer has been subsequently used in the tanning and post‐tanning process. The influence of the carboxyl group increases the metal uptake of the aluminum (twofold) and zirconium (1.5‐fold) tanning agent, and hydrothermal stability of the polymer‐treated leathers is 74 and 81°C for aluminum and zirconium tanning, respectively. The experimental leather showed uniform pore size distribution and better organoleptic characteristics than the control. Introducing the quaternary ammonium group in the polymer increased dye exhaustion in the experimental process up to 97%. The anti‐bacterial studies show the polymer is effective against gram‐positive species due to electrostatic interaction. The biochemical analysis of the experiment process shows higher biodegradability (0.62). Thus, the present study opens a new avenue for a sustainable replacement for conventional post‐tanning chemicals.

Improving ion rejection by optimizing the structure and charge distribution of the Janus membrane

Due to the asymmetry of charge distribution and geometric structure, the Janus membrane can simultaneously intercept counter-ions and co-ions. This work constructed four Janus membrane configurations using numerical simulation methods. Due to the different potential within the membrane and the selectivity level, there is a significant deviation in the interception performance. The results found that the change in the height of the Janus membrane affects the distribution of anion and cation concentration inside the nanochannel, and the asymmetry of the nanochannel height is more conducive to interception than a uniform nanochannel. The effect of the nanochannel length of the first section on the rejection rate is higher than that of the second section. Considering the design of the membrane, we recommend that the pore length of the first section be set to about 50 nm. Since the flow potential balances the electroviscous force, the optimization of the flow rate for ion transport is often opposite to the interception effect. The Janus membrane has asymmetric pore size and charge distribution characteristics and has excellent retention ability for divalent salts under low-pressure intensity and high-concentration conditions.

Experimental study on the effect of circulating liquid velocity on bubble size distribution and turbulence characteristic in an external loop airlift reactor

AbstractThe influence of circulating liquid velocity on bubble size distribution (BSD) and turbulence characteristics of an external loop airlift reactor was studied in this paper. The instantaneous and time‐averaged velocity in the riser were studied using particle image velocimetry (PIV), and BSDs were measured by digital image analysis technique based on machine learning. Then turbulence kinetic energy (TKE) and energy dissipation rate (EDR) were calculated through the velocity field. The results indicate that as the circulating liquid velocity increased, the peak value of BSD rapidly decreased from nearly 6 mm to approximately 2 mm. The radial velocity of the liquid gradually decreased and changed direction, eventually increasing again. TKE first decreased and then increased. Compared with bubble flow with a BSD peak of 2–6 mm, bubble flow with a BSD peak of 2 mm had larger TKE. The radial movement of bubbles had great influence on the turbulence characteristics. This study demonstrates that selecting an appropriate circulating liquid velocity can reduce the diameter of bubbles while obtaining greater TKE, thereby improving the mass transfer and reaction efficiency in external loop airlift reactors (EL‐ALR).