Particle Interception Research Articles

Simple preparation of V2O5-WO3/TiO2/SiC catalytic membrane with highly efficient dust removal and NO reduction

Simplifing the preparation process is an efficient method to reduce process energy consumption and product costs. In this work, a one-step vacuum impregnation technology was developed for the preparation of V2O5-WO3/TiO2 catalyst modified SiC (VWTi/SiC) catalytic membranes. In comparison to VWTi/SiC (II) catalytic membrane prepared by the traditional two-step method, the VWTi/SiC (I-X) catalytic membrane prepared via one-step vacuum impregnation technology demonstrate significant advantages in terms of energy saving and consumption reduction. Owing to the strongest activation ability for O2 and NH3 induced by high V4+ species and strong V-W interaction, the optimal VWTi/SiC (I-500) can achieve 90 % ammonia selective catalytic reduction (NH3-SCR) denitrition efficiency at the temperature range from 200 °C to 350 °C, presenting a much higher NH3-SCR activity than VWTi/SiC (II-500). The evaluation of sulfur resistance, long-term stability and dust filtration performance proposed that VWTi/SiC (I-500) demonstrated excellent sulfur resistance and outstanding long-term stability and excellent dust filtration performance (particle interception rate exceeds 99.9 % for typical 2.5 μm silicon dioxide particles) at various condition. Therefore, the VWTi/SiC catalytic membrane prepared by one-step vacuum impregnation method holds great promise and development potential for high-temperature flue gas purification.

Solute-particle separation in microfluidics enhanced by symmetrical convection.

The utilization of microfluidic technology for miniaturized and efficient particle sorting holds significant importance in fields such as biology, chemistry, and healthcare. Passive separation methods, achieved by modifying the geometric shapes of microchannels, enable gentle and straightforward enrichment and separation of particles. Building upon previous discussions regarding the effects of column arrays on fluid flow and particle separation within microchips, we introduced a column array structure into an H-shaped microfluidic chip. It was observed that this structure enhanced mass transfer between two fluids while simultaneously intercepting particles within one fluid, satisfying the requirements for particle interception. This enhancement was primarily achieved by transforming the originally single-mode diffusion-based mass transfer into dual-mode diffusion-convection mass transfer. By further optimizing the column array, it was possible to meet the basic requirements of mass transfer and particle interception with fewer microcolumns, thereby reducing device pressure drop and facilitating the realization of parallel and high-throughput microfluidic devices. These findings have enhanced the potential application of microfluidic systems in clinical and chemical engineering domains.

Effects of microtopography shaping on characteristics of eroded sediment particles of a dump slope in an opencast coal mine in China

AbstractThe properties of sediment particles are crucial research areas for understanding soil erosion on dump slopes. In this study, the slope of the southern dump of the ATB opencast coal mine in the Pingshuo mining area in Shanxi Province, China, was selected to conduct microtopographical shaping and artificial rainfall simulation experiments. Three different gradients of rainfall intensity, 20, 50, and 80 mm·h−1, were set. The main component of rainwater was water (chemistry H2O) by a rainfall duration of 30 min. A Microtrac S3500 laser particle size analyzer was used to measure the collected erosion sediment particles. This study conducted level benches and fish‐scale pits microtopography shaping on the slope of the waste dump. The dimensions of the level bench design were 1, 2, and 1 m for the step width, for the step length, and between each level bench, respectively. The fish‐scale pits were 60 cm (length), 40 cm (width), and 30 cm (depth). The horizontal and row spacing of each fish‐scale pit was 1 m, and an unshaped terrain was used as the control group. Through dynamic monitoring and statistical analysis of the data, the impacts of rainfall intensity and microtopography shaping mode on the features of the eroded sediment particles were analyzed. Fine silt particles (53%) were lost as a result of the surface erosion of the slope. The mean starting periods of sediment particle loss decreased with the increase in rainfall intensity (589 s > 402 s > 305 s). Additionally, the clay and silt particle enrichment ratios decreased (ER >1), whereas the sand particle enrichment ratios increased (ER <1). The level benches had a stronger interception effect on fine sediment, whereas the fish‐scale pits had a weaker interception effect on sediment particles under heavy rain. The distribution properties of erosion sediment particles on a slope can be assessed using fractal dimension as an index. This study is significant for understanding the erosion mechanism of eroded sediment particles on dump slopes and provides a scientific foundation for soil erosion control on opencast coal mine dump slopes in the Loess Plateau. These results highlight the potential for the level bench to effectively delay the occurrence of runoff and greatly enhance the interception of sediment particles.

Microplastic trapping efficiency and hydrodynamics in model coral reefs: A physical experimental investigation

Coastal ecosystems, such as coral reefs, are vulnerable to microplastic pollution input from proximal riverine and shoreline sources. However, deposition, retention, and transport processes are largely unevaluated, especially in relation to hydrodynamics. For the first time, we experimentally investigate the retention of biofilmed microplastic by branching 3D printed corals (staghorn coral Acropora genus) under various unidirectional flows (U = {0.15, 0.20, 0.25, 0.30} ms−1) and canopy densities (15 and 48 corals m−2). These variables are found to drive trapping efficiency, with 79–98% of microplastics retained in coral canopies across the experimental duration at high flow velocities (U = 0.25–0.30 ms−1), compared to 10–13% for the bare bed, with denser canopies retaining only 15% more microplastics than the sparse canopy at highest flow conditions (U = 0.30 ms−1). Three fundamental trapping mechanisms were identified: (a) particle interception, (b) settlement on branches or within coral, and (c) accumulation in the downstream wake region of the coral. Corresponding hydrodynamics reveal that microplastic retention and spatial distribution is modulated by the energy-dissipative effects of corals due to flow-structure interactions reducing in-canopy velocities and generating localised turbulence. The wider ecological implications for coral systems are discussed in light of the findings, particularly in terms of concentrations and locations of plastic accumulation.

Microchannel structure affects fine particulate pollutant interception characteristics

Deep filtration is an important technology for the separation of fine particle pollutants in industrial wastewater. The theoretical core of microchannel separation is the interaction between channel interface and pollutants. Here, microchannels with different shapes and sizes were designed by microfluidic technology and the particle migration process in microchannels was visualized by high-speed camera. This paper studied the effects of apparent depth, inlet structure and channel angle of the interception channel on fluid flow and particle interception. When apparent depth of the interception channel was equidistantly distributed, the flow rate in each channel was uniform, but interception efficiency gradually decreased with the increase of apparent depth. Interception efficiency of the first layer was 16.7 %, while for the 14th layer was only 0.4 %. Interception performance of the upper wall of the inlet of the interception channel was substantially higher than that of the lower wall. The smoother the angle between the interception channel and the mainstream channel was, the better the interception performance. When the angle between the upper and lower walls of the inlet and the mainstream channel was 30° and 60°, respectively, interception efficiency was the optimal, and cumulative interception efficiency of the three filtrations was 92.4 %. Additionally, flow rate and interception efficiency of the interception channel increased with decreasing channel angle. The total interception performance of the 30°–45° group was the optimal, and the total split ratio and total interception efficiency were 65.5 % and 85.5 %, respectively. This provides reference for the change of microchannel structure and the mechanism of particle migration and deposition.

Insights into the Mechanism of Coagulation Pretreatment for Membrane Fouling Control from the Perspective of Organic Removal Based on a Sensitive SEC-DAD-FLD-OCD/OND Method

Organic matters, especially low molecular (LMW) ones, contribute to the serious membrane fouling, but the traditional coagulants cannot efficiently remove LMW substances. Herein, the coagulation-ultrafiltration combined process (C-UF) was applied to the actual lake water treatment, and a novel polyaluminum titanium composite coagulant (PATC) was used as a pretreatment reagent for membrane fouling mitigation. The results indicated that PATC performed better to efficiently remove organic matters than polyaluminium chloride (PAC) and polytitanium chloride (PTC). Notably, PATC could effectively remove building blocks and LMW substances, particularly the protein-like fluorescent substances. The removal mechanism of LMW substances by PATC was mainly the adsorption of amorphous hydrolysates, rather than the charge neutralization of positively charged hydroxy complexes. No matter with or without the cake layer, the control performance of the three coagulants on membrane fouling was consistent with their removal efficiency of organics. It indicated that although the cake layer played an important role in the interception of organics and small particles, it was not the decisive factor in lightning membrane fouling. Improving the removal efficiency of organic substances, especially the LMW component, is the key to alleviate membrane fouling. This work provides a new insight into the effects of the composite coagulant on the removal of various organics and the control of membrane pollution in actual lake water treatment.

Performance factors for filtration of air using cellulosic fiber-based media: A review

The filtration of air has attracted increasing attention during recent waves of viral infection. This review considers published literature regarding the usage of cellulose-based materials in air filtration devices, including face masks. Theoretical aspects are reviewed, leading to models that can be used to predict the relationship between structural features of air filter media and the collection efficiency for different particle size classes of airborne particulates. Collection of particles can be understood in terms of an interception mechanism, which is especially important for particles smaller than about 300 nm, and a set of deterministic mechanisms, which become important for larger particles. The effective usage of cellulosic material in air filtration requires the application of technologies including pulp refining and chemical treatments with such additives as wet-strength agents and hydrophobic sizing agents. By utilization of high levels of refining, in combination with freeze drying and related approaches, there are opportunities to achieve high levels of interception of fine particles. A bulky layer incorporating nanofibrillated cellulose can be used in combination with a coarser ply to achieve needed strength in a filter medium. Results of recent research show a wide range of development opportunities for diverse air filter devices containing cellulose.

Simulation of particle interception of seamless knitted composite filter material based on the discrete phase model

In this research, a three-dimensional geometric model of knitted cylindrical air filter material is constructed. Due to the isotropy of the three-dimensional structure, a certain cyclic structure is selected for the flow calculation domain in this research. According to the principle of air filter particle testing, the pressure drop of the filter material and the particle collection efficiency are simulated and calculated. Applying ANSYS finite element analysis software, based on Fluent's fluid Lagrangian discrete model, the geometric model is meshed and the particle materials and boundary conditions are set. Air is the continuous phase, and its velocity is set at 0.27 m/s. The jet particles are used as discrete phases to track the particle trajectory in real time. Based on the above conditions, the simulation of the capture efficiency of weft-knitted tubular air filter material for different particle sizes can not only predict and evaluate the filtering efficiency of the knitted tubular air filter material, but also provide a theoretical reference for fluid simulation of the knitted filter material.

Air pollutant removal by four sidewalk tree species in the largest city in Taiwan.

Air pollutants pose risks to human health, especially in densely populated cities. We compared the interception of suspended particles and metal elements by four sidewalk tree species with different leaf surface wettability (based on contact angle), leaf area, and phenology in Taipei, Taiwan. Suspended particles were enriched 2.0-2.5 times in throughfall relative to rainfall due to wash-off of suspended particles deposited on leaf surfaces during rainless periods. The enrichment in throughfall was greater in tree species with larger leaf areas. Despite greater concentrations of suspended particles in rainfall during the low-leaf-area period, enrichment was greater in the high-leaf-area period, indicating that leaf area was a key factor affecting canopy interception of pollutants. Throughfall enrichment of suspended particles positively correlated with water quantity, indicating that air pollutants intercepted by tree canopies were not fully washed off by rainfall. Annually, ∼830g of suspended particles were intercepted and washed off from one tree canopy, with a crown area of 42 m2 . Scaling up, a rough estimate of 72.7 Mg of suspended particles were intercepted annually by the 90,000 sidewalk trees in Taipei City. Copper, chromium, and aluminum were enriched in throughfall compared with rainfall. However, lead was depleted in throughfall, indicating greater interception than wash-off. Based on our results, leaf area and length of foliated period are key characteristics affecting canopy interception of particulate matter and associated metal elements, whereas leaf surface wettability is of secondary importance.

The Dew Particle Interception Abilities of Typical Plants in Northeast China Plant Leaves Capture Particles in Dew

The dew condensation frequency is high, and the dew amount is heavy in urban ecosystems. During the condensation process, particulate matter acts as a condensation core, playing an important role in purifying the air. At night, dew mainly condenses on plant leaf surfaces, the plant leaves settle the particles in the dew, and some of the particles are resuspended into the atmosphere in the process of dew evaporation after sunrise. This paper monitored the condensation and evaporation processes of dew on four common plants in Changchun city from June to September 2020. By analyzing the mass and size of particles on different leaves after dew condensation and evaporation, the ability of different plants to retain particles in dew was analyzed. The results showed that there was no significant difference in the TSP capture ability during dew condensation between Buxus sinica (Rehd. et Wils.) Cheng subsp. sinica var. parvifolia M. Cheng, Syringa oblata Lindl., Hemiptelea davidii (Hance) Planch., and Pinus tabuliformis Carrière, with a TSP content of 0.21 ± 0.06 μg/cm2. Coarse particulate matter is the main type of deposit in the dew condensation stage. Particulate deposition varied according to species, leaf shape, and microstructure. The proportion of TSP remaining on leaves after dew evaporation from Pinus tabuliformis Carrière, Hemiptelea davidii (Hance) Planch., Buxus sinica (Rehd. et Wils.) Cheng subsp. sinica var. parvifolia M. Cheng, and Syringa oblata Lindl. tree was 89.7 ± 3.9%, 80.6 ± 3.6%, 75.9 ± 4.5%, and 71.4 ± 3.7%, respectively. The ability of the leaves to trap fine particles was significantly higher than that for coarse particles ( P < 0.05 ) after dew evaporation. The highest amount of particle captured by Syringa oblata Lindl. individual was 15.17 g/y during dew condensation, and the amount of remaining particles after dew evaporation was 10.83 g/y. This paper provides a theoretical basis for the selection of tree species for urban greening.

Grain Size and Sedimentary Sorting Characteristics of Atmospheric Dust in the Cele Oasis, Southern Margin of Taklimakan Desert

Grain size is a proxy indicator of airflow intensity and also provides a scientific basis for the prevention of dust hazards. However, the variations in grain size characteristics that occur during transport and deposition processes are seldom discussed. Here, atmospheric dust samples were collected before and after deposition in a sand–dust storm for grain size analysis. The results showed that the grain size distributions of the atmospheric dust were unimodal during transportation but always became bimodal after deposition. This indicates that the bimodal grain size distribution of the aeolian deposits was caused by sedimentary sorting. The coarse-grained component, which was between 20 and 200 μm, was mainly deposited during the sand–dust storm. Grain size may indicate the strength of the airflow field. The fine-grained component, which ranged in size from 0.4 to 20 μm, was mainly deposited after the sand–dust storm. This component can remain suspended in the atmosphere for a long period of time. Oasis shelterbelts can be used to reduce the fine-grained component of the dust aerosol through the interception of particles by foliage. The grain size variation found in this study from before to after sand–dust storm deposition deepens our understanding of the sediment sorting process.

Observation of breakdown wave mechanism in avalanche ionization produced atmospheric plasma generated by a picosecond CO2 laser

Understanding the formation and long-timescale evolution of atmospheric plasmas produced by ultrashort, long-wavelength infrared (LWIR) pulses is an important but partially understood problem. Of particular interest are plasmas produced in air with a peak laser intensity ∼1012 W/cm2, the so-called clamping intensity observed in LWIR atmospheric guiding experiments where tunneling and multi-photon ionization operative at near-IR or shorter wavelengths are inoperative. We find that avalanche breakdown on the surface of aerosol (dust) particles can act to seed the breakdown of air observed above the 200 GW/cm2 threshold when a train of 3 ps 10.6 μm laser pulses separated by 18 ps is used. The breakdown first appears at the best focus but propagates backward toward the focusing optic as the plasma density approaches critical density and makes forward propagation impossible. The velocity of the backward propagating breakdown can be as high as 109 cm/s, an order of magnitude greater than measured with ns pulse-produced breakdown, and can be explained rather well by the so-called breakdown wave mechanism. Transverse plasma expansion with a similar velocity is assisted by UV photoionization and is observed as a secondary longitudinal breakdown mechanism in roughly 10% of the shots. When a cm-size, TW power beam is propagated, interception of aerosol particles is guaranteed and several (40 cm−3) breakdown sites appear, each initially producing a near-critical density plasma. On a 10 ns–1 μs timescale, shockwaves from each site expand radially and coalesce to produce a large hot gas channel. The radial velocity of the expansion agrees well with the prediction of the blast wave theory developed for ultrafast atmospheric detonations.

Purification of bathing wastewater by double suspended layer fluidized bed reactor.

An external radial magnetic field and built-in stainless steel balls formed a magnetic suspended layer (MSL), as observed in this study. Under the condition of crossflow inflow, the flocculating agent and coagulant aids form a flocculated particles suspension layer (FPSL). Thus a double suspended fluidized bed reactor was constructed to treat bathing wastewater. A particle image velocimetry device was used to detect flow patterns and analyze the flocculation conditions. The results showed that under the condition of crossflow inflow, at the same time, the flooding water was 0.023-2.101 m3/h, and the dosage of poly aluminum chloride (PAC) and polyacrylic amide (PAM) was 90 mg/L and 1.5 mg/L, respectively, and removal rates of turbidity, chemical oxygen demand (CODCr) and linear alkylbenzene sulphonates (LAS) reached more than 99, 90, and 80%. Filtration, grid flocculation and particle interception were functions of the MSL. Meanwhile, the crossflow input created additional vortexes, increasing the likelihood of flocculation particle collision, improving the flocculation conditions and cleaning the MSL. The reactor aids in the development of the initial flocculated particles suspension layer, flocculation strengthening, chemical dosage reduction, effluent qualities improvement, and effluent stability maintenance.

Theory and technology of air filtration: review

The development of modern science and technology, improving the level of industrialization, increase people's awareness of environmental protection were leaded to the world's demand for filter materials to purify the air. This review presented an overview of air pollutants classification, history of fiber materials, theory of air filtration technology, and traditional air filtration (materials, characteristics, advantages, disadvantages, and standards). In addition, the paper reviewed the mechanisms of filtration, which include diffusion, interception, intermolecular interaction, straining, inertial impaction, gravitation, and electrostatic interaction of particles on the filter surface. Different studies have revealed the possibilities for the utilization of activated carbon fiber in the removal of VOC or odor from gaseous emissions in the air.

Practical optimization of scale removal in circulating cooling water: Electrochemical descaling-filtration crystallization coupled system

• Superior removal rates of EC-FC system compared with EC system. • Effective interception of scale particles in effluent of EC module. • The function of FC module to alleviating ohmic heat from EC reactor. • More efficient operation in high current density of EC-FC system than EC. Targeting for the problems in industrial circulating cooling water system resulted from scale formation, researchers have proposed a variety of treatment solutions, among which electrochemical descaling is one of the most promising technology. At present, the main barrier in electrochemical scale removal is relatively insufficient treatment efficiency. One possible reason for this is that the scale particles generated by electrochemical process cannot be effectively deposited on the cathode of the reactor but flow out of the electrochemical reactor. To this problem, this paper proposed a coupled system that connected the filter crystallization module after the electrochemical descaling process. By doing so, it was expected to filter and intercept scale particles, thus improving the overall performance of treatment. The experimental results attested that the introduction of filtration crystallization (FC) system could improve the performance of electrochemical-filtration crystallization (EC-FC) system in hardness removal rate, alkalinity removal rate, total dissolved solids (TDS) removal rate and water sample temperature difference. With the promotion effect from FC system, the scale particles in the effluent from the EC system can be effectively intercepted, and inductive crystallization of the scale ions can be achieved for further purification. Different from EC system, the descaling efficiency of EC-FC system escalated continuously with the rise of current density, while decreased first and then went up with the shortening of hydraulic retention time. However, EC system determined the upper limit of the treatment performance of the whole system. It was because FC system can only deposit the scale particles that were not deposited on the cathode plate on the filler, but cannot react to produce new scale formation ions. Through our proposal and investigation, this work provides an original facile idea for the practical application of electrochemical scale removal technology with proved feasibility.

Study of electrostatic parameters of aqueous suspensions for solving the tasks of water treatment and selection of optimal filter media

Relevance of research. At present, there is a need for a comprehensive study of both physical and chemical parameters of substances, which is the primary source of deteriorating treated water quality, as well as the relevant physical properties of the actual filter media to determine the mechanism of their interaction. Such a parameter of purified water as turbidity is closely related to the electrostatic properties of the colloids contained in water. For a more detailed experimental study of this interaction, an operating water treatment facility was chosen. A preliminary study of the conditions at the Communal Enterprise "Chernivtsivodokanal" in the city of Chernivtsi, Ukraine made it possible to identify the typical problems that need to be immediately addressed. The study revealed that the main indicator that is critical for the purification of these waters is turbidity, and one of the main growing concerns to be addressed is the replacement of the filter media.
 Research results. To select optimal filter media, a comprehensive study of the electrostatic parameters of all components in the water treatment process was carried out. Experimental studies of physical quantities that are key to this process were performed. The relationship between the turbidity parameters of the studied waters and the ζ-potential of the colloids contained in them was shown. Seasonal changes in the hydrochemical composition of the treated waters were studied. The connection between electrochemical parameters of clay particles and the processes of their sedimentation in aqueous suspension is given. The dependences of turbidity on time and the ratio of average turbidity values to the minimum and maximum ones at the water intake of the Dniester-Chernivtsi water supply system during 2005-2015 were reviewed and presented. The dynamics of changes in the parameters of turbidity and ζ-potential in the structures of the technological chain of water treatment during the periods of summer-autumn floods and low-water winter period was studied. The effect of the coagulant used at the studied water treatment facility on the electrostatic parameters of the purified colloidal particles, in particular, on changing the structure of the electric double layer of clay particles, which lead to the coagulation and reduction in the treated water turbidity, was analyzed. The optimal conditions of using polystyrene foam and zeolite filter media were determined. Ion exchange properties enabled the zeolite to efficiently remove fine colloidal particles with positively charged cores out of the purified aqueous suspension, which were not completely covered with a layer of potential-forming ions. However, they produced impact only in the short-term initial stage of filtering. Therefore, they cannot be recommended for using for long-term water treatment processes at water treatment facilities. This phenomenon is due to the limited ion exchange adsorption properties of zeolite. The effective filtration of colloidal particles through zeolite in the year-round mode of operation at the studied water treatment facility is mainly associated with the developed outer surface of its grains, which provides mechanical interception and retention of colloidal particles.
 Conclusions. The connection between the turbidity parameters and colloids ζ-potential of the purified aqueous suspension for the conditions of water quality formation in the upper reaches of the Dniester River has been established. The determined values of the ζ-potential of colloids enabled to find out that the polystyrene foam filter media is more expedient to use during the flood periods, and the application of the zeolite media has a higher efficiency during the low-water periods. The ion exchange properties of zeolite can ensure a high level of water purification during floods; however it can be only efficient at the initial stage of filtration. Effective mechanical interception and retention of colloidal particles in the year-round regime is provided by the developed surface of its grains. The combined polystyrene foam and zeolite filter media is recommended to use to solve the problems of water treatment throughout the year.

A Functional Form for Fine Sediment Interception in Vegetated Environments

The body of literature seeking to evaluate particle interception in vegetated, aquatic environments is growing; however, comparing the results of these studies is difficult due to large variation in flow regime, particle size, vegetation canopy density, and stem configuration. In this work, we synthesize data from these studies and develop a functional form of particle interception efficiency (η) as a function of stem Reynolds number (Rec), stem diameter, vegetation frontal area, particle–collector diameter ratio, flow velocity, and kinematic viscosity. We develop this functional relationship based on a dimensional analysis and hypothesize that the coefficients would exhibit regimes within different Rec ranges. We test this hypothesis by synthesizing data from 80 flume experiments reported in the literature and in-house flume experiments. Contrary to our hypothesis, data from different Rec ranges follow a single functional form for particle interception. In this form, η varies strongly with collector density and particle–collector diameter ratio, and weakly with Rec and particle–fluid density ratio. This work enables more accurate modeling of the flux terms in sedimentation budgets, which can inform ongoing modeling and management efforts in marsh environments. For example, we show that by integrating the new functional form of particle interception into established models of marsh elevation change, interception may account for up to 60% of total sedimentation in a typical silt-dominated marsh ecosystem with emergent vegetation.

Antibacterial and antiviral N-halamine nanofibrous membranes with nanonet structure for bioprotective applications

The recent outbreak of a coronavirus disease (COVID-19) has posed a great threat to public health and financial system. Most current masks used to prevent the spread of COVID-19 are typically absence of biocidal properties. We designed a novel polymer, polystyrene grafted by 5, 5-dimethylhydantoin and trimethylamine (PSDT), which possesses halamine site and cationic quaternary ammonia salt site. Furthermore, PSDT/PU nanofiber@net membranes (PSDT/PU NNMs) were obtained by electrospinning technology. Our strategy enables inherent N-halamine and quaternary ammonia salt (QAS) group to be covalently integrated into membranes, realizing the efficient and stable biocidal properties. Meanwhile, the introduction of nanonets endows electrospun membranes with prominent air filtration performance. The resulting membranes exhibit integrated properties of high interception of fine particles (96.7%) and low pressure drop (95.4 Pa). Besides, chlorinated PSDT/PU nanofiber@net membranes (with active chlorine content of 0.60 wt% and quaternary ammonia salt content of 2.20 wt%) exhibited superior bactericidal (>99.9999%) and virucidal (>99.999%) efficiency in a short time (2 min), which enables chlorinated PSDT/PU NNMs to be served as the filtration material by providing bacterial interception (99.77%) and contact killing against pathogens. The successful synthesis of PSDT/PU NNMs provide innovative insights for exploring filtration materials in a nanonet and biocidal form.

Study on the Process and Characteristics of Clogging for Ceramic Permeable Brick

A ceramic permeable brick was selected for study in a device that was designed to fully investigate the process and characteristics of clogging in permeable bricks. In order to evaluate the permeability influenced by clogging, a simulated rainfall was filtered through the permeable brick placed in an innovative device. The macroscopic and microscopic changes in the brick and the filtrate were all measured to fully investigate the causes and process of clogging. Then, the mechanism of clogging in the permeable brick pores was further discussed. The results showed that the clogging risk of permeable brick was extremely high, and it can result in a complete clogging in only 5–10 years under the experimental conditions. The permeability coefficient and porosity both decreased exponentially with the increase in filtrate, which was attributed to the clogging of the internal pore structure due to particle interception. The chord size distribution results stressed that the blockage mainly occurred in the upper layer pores in the range of 0.5–1.5 mm, which is relatively sensitive to clogging due to the particle size distribution in rain water. The particle size distribution of the influent and effluent indicated that the clogging process could completely remove particles larger than 88 µm but showed variable removal efficiency for particles with sizes of 20–88 µm. This research offers new insight into the clogging of permeable bricks and provides theoretical guidance for restoring the brick permeability.

Air pollution, human health and the benefits of trees: a biomolecular and physiologic perspective

ABSTRACT It is well accepted that particulate matter (PM) can affect human health detrimentally. Chronic and prolonged exposures to particulate matter with an aerodynamic diameter ranging between 2.5 and 10 microns (PM10), 0.1 and 2.5 microns (PM2.5) and less than 0.1 microns in size (UFPM), have been associated with cardiopulmonary diseases. PM is ubiquitously present in urban settings, while primarily absent in forest environments primarily due to the direct interception of airborne pollution particles by trees. Both short- and long-term exposure to trees in forested environments is associated with lower blood pressure and inflammation, as well as enhanced immune function. Additionally, exposure to volatile organic compounds (VOCs) actively released by trees is associated with improved health through enhanced natural killer cell activity, reduced inflammatory responses, and reduced psychological stress. This article presents the results of a literature review on the harmful health effects of air pollution in urban environments, and the potential of forested environments to promote health and disease prevention.