Filtered Air Research Articles

Sunlight-Driven Self-Cleaning Ultrafine Particulate Matter Filter with Antibacterial Activity.

Air pollution by particulate matter (PM) and airborne pathogens causes severe health problems in the human body. Presently, popular disposable air filters yield huge waste and have a fatal impact on the environment. Postuse cleaning of air filters also leads to secondary air and water pollution. Here, we report a sunlight-driven self-cleaning PM filter by coupling a full-solar-spectrum-active photocatalyst comprising up-conversion nanoparticles (UCNPs) decorated with semiconductor iron(III) oxide (UCNP@α-Fe2O3) shells stabilized upon graphene functionalized borosilicate fibrous membrane (rGO-BF). While rGO-BF ensures high PM adsorption, UCNP@α-Fe2O3 (NP) enables self-photodegradation of adsorbed PM under abundant sunlight and subsequent membrane regeneration, while preventing secondary air or water pollution. Rational surface chemistry and optimal microstructure enable our filters to remove >99% of PM2.5 under deplorable air-quality conditions. Moreover, our filter shows excellent antibacterial activity toward E. coli and S. aureus, demonstrating its potential for practical utilization in face masks, air filtering devices, and protective medical wear. This work successfully suggests an intriguing design platform for self-sustainable zero-waste air filter membranes.

Revolutionizing Airborne Virus Defense: Electromagnetic MXene-Coated Air Filtration for Superior Aerosol Viral Removal.

The COVID-19 pandemic sparked public health concerns about the transmission of airborne viruses. Current methods mainly capture pathogens without inactivation, leading to potential secondary pollution. Herein, we evaluated the inactivation performance of a model viral species (MS2) in simulated bioaerosol by an electromagnetically enhanced air filtration system under a 300 kHz electromagnetic induction field. A nonwoven fabric filter was coated with a 2D catalyst, MXene (Ti3C2Tx), at a coating density of 4.56 mg·cm-2 to absorb electromagnetic irradiation and produce local heating and electromagnetic field for microbial inactivation. The results showed that the MXene-coated air filter significantly enhanced the viral removal efficiency by achieving a log removal of 3.4 ± 0.15 under an electromagnetic power density of 369 W·cm-2. By contrast, the pristine filter without catalyst coating only garnered a log removal of 0.3 ± 0.04. Though the primary antimicrobial mechanism is the local heating as indicated by the elevated surface temperature of 72.2 ± 4 °C under the electromagnetic field, additional nonthermal effects (e.g., dielectrophoresis) on enhanced viral capture during electromagnetically enhanced filtration were investigated by COMSOL simulation to delineate the potential transmission trajectories of bioaerosol. The results provide unique insights into the mechanisms of pathogen control and thus promote alternative solutions for preventing the transmission of airborne pathogens.

Experimental study of materials for the filtration of the intake air of the internal combustion engine of a motor vehicle

Experimental evaluation of the properties of filter materials in the selection of material for filtration of inlet air of internal combustion engines was carried out. The filtration characteristics were determined: filtration efficiency and accuracy, as well as flow resistance depending on the dust mass load. Filter materials based on cellulose, polyester, microfiber glass, and cotton and polyester nonwoven beds were studied. Two filter beds consisting of three base filter materials were designed: composite K1 (polyester-microglass-cellulose) and composite K2 (cellulose-microglass-cellulose), and their characteristics were performed. The air filtration quality factor was used to analyze the test results. The coefficient of filtration efficiency was defined, showing the effect of the preliminary stage on the total time of the filtration process. It was shown that the K1 composite has high (dpmax = 1.5÷3 µm) filtration accuracy, high initial filtration efficiency (99.8%), which shortens the pre-stage, and extends to 96-98% the duration of the main stage of the filtration process. The K1 composite obtained more than twice the mass loading of dust (kdK1 = 148,9 g/m2), which will allow the vehicle's mileage to be extended.

Virus removal by high-efficiency air (HEPA) filters and filtration capacity enhancement by nanotextiles: a pilot study.

Portable household air purifiers are widely used devices designed to maintain a high-quality level of indoor air. Portable air purifiers equipped with the high-efficiency air (HEPA) filter served 100h in a household space occupied by two adults without any symptoms of respiratory tract infection. The main objective of the study was to determine microbial contamination on the HEPA filter and to investigate if the selected nanotextile monolayer made of polyamide 6 (PA6) nanofibers can capture potential microorganisms when installed downstream of the HEPA filter as the final filtration medium. Samples were taken from the inlet and outlet surfaces. Samples from the nanotextile were collected in the same manner as from the HEPA filter. QIAStat DX® 1.0 Analyzer using the Respiratory SARS CoV-2 Panel multiplex PCR detection system was selected for microorganism detection. Adenovirus was detected on the inlet surface of the HEPA filter. The outlet surface of the filter contained no viruses included in the Respiratory SARS CoV-2 Panel portfolio. The nanotextile monolayer was replaced twice during the 100h of operation, so three pieces were used and all contained coronavirus 229 E. Coronavirus 229 E was then detected in the nasopharynx of one of the members of the household as well. It may be assumed that the selected nanotextile is capable of capturing a virus of a small size.

Impact of Synthetic Textiles Emission in Sports Car Furnishing -An Overview

A sports automobile is one that is built with a focus on dynamic performance, including handling, acceleration, top speed, driving excitement, and the ability to race. Sports cars and other performance automobile categories, including muscle cars, are not always mutually exclusive; in fact, some cars can fit into more than one category. The automotive sector is the biggest consumer of technical textiles; each of the approximately 45 million cars produced globally each year uses around 20 kilograms of textiles. Undoubtedly, design and textiles will be crucial components in producing these unique homes. Not only do carpets and textile headliners enhance the general cosiness and aesthetics of the room, for high-pressure belts and hoses, reinforcing textile strands are necessary. Numerous air and oil filters, as well as bonnet liners, use non-woven materials. This essay addresses the issue of pollution caused by sports vehicle emissions of synthetic textiles and explores potential solutions. The use of synthetic materials in motor sports automobiles accounts for about 82% of all synthetic fabrics released into the atmosphere. Exhaust emissions account for 76% of the share of sports cars, evaporation for 22%, and refuelling for 2%. Human health issues resulting from emissions from synthetic textiles include cancer in cases of extended exposure and a host of other ailments in cases of shorter exposure. This paper gives an overview of the impact of man-made textile emissions on sports car furnishing and its source of reduction.

Persistence of emphysema following cessation of cigarette smoke exposure requires a susceptibility factor.

Chronic obstructive pulmonary disease (COPD) is caused by cigarette smoke (CS) exposure but can often be progressive even in former smokers. Exposure of mice to CS for 22 wk causes emphysema, but whether emphysema persists after cessation of CS exposure is not clear. The purpose of this study was to determine whether emphysema persists in mice following a recovery period of 22 wk and whether a susceptibility factor, such as deficiency in the Bcl-2-interacting killer (Bik), is required for this persistence. Therefore, bik+/+ and bik-/- mice at 6-10 wk of age were exposed to 250 mg/m3 total particulate matter of CS or filtered air (FA) for 3 or 22 wk and were kept in FA for an additional 22 wk. Lungs were lavaged to quantify inflammatory cells, and sections were stained with hematoxylin and eosin to assess severity of emphysema. Exposure to CS for 3 wk increased the number of inflammatory cells in bik-/- mice compared with bik+/+ mice but not at 22 wk of exposure. At 22 wk of CS exposure, extent of emphysema was similar in bik+/+ and bik-/- mice. However, when mice were exposed to CS over the first 22 wk and were kept in FA for an additional 22 wk, emphysema remained similar in bik+/+ mice but was enhanced in bik-/- mice. These findings link increased inflammation with persistent emphysematous changes even after smoking cessation and demonstrate that a preexisting susceptibility condition is required to sustain enhanced emphysema that was initiated by long-term CS exposure.NEW & NOTEWORTHY Exposure of mice to cigarette smoke (CS) for 22 wk causes emphysema, but whether emphysema persists after an additional period of 6 mo after cessation of CS exposure has not been reported. In addition, the role of preexisting susceptibility in enhancing the persistence of CS-induced emphysema after exposure to CS has stopped has not been shown. The present study shows that a preexisting susceptibility must be present to enhance CS-induced emphysema after cessation of CS exposure.

The Climate and Global Warming Responses to the Changing Greenhouse Gas Concentration in the Atmosphere

Increase of the World temperature throughout the Earth is called Global warming. Studies have shown that Temperature of the earth have risen, if do not stopped on time, it will rise further. The reason of this global warming are Greenhouse gases like, Nitrous Oxide, Carbon Dioxide, Methane, Sulphurehexafloride, Nitrogen Trifloride, Hydrofluorocarbon, Perfluorocarbon. Global warming of the Nitrous oxide is 265 and can stay up to 121 years in the atmosphere. It has 298 times more potential in the warming up of the glob than Carbon dioxide, which are being produced by human’s industrial activities. Therefore Carbon dioxide is being produced with the burning of the fossil fuels and the ability of the Carbon dioxide in global warming 1. Methane is a gas which is being produced by the burning of the organic materials. Sulphur Hexafluoride is also a strong gas of the greenhouse gases and is unburnable and is able to wipe out the infrared waves. It keeps the earth warm for a long time. Nitrogentrichloride is a gas which causes skin and eye’s disease. Therefore, every molecule of the Hydrofluorocarbon is much stronger as compare to the Carbon dioxide. It prevents the distraction of the Ozone layer. On the other side, perfluorocarbon is a gas which has the ability to wipe out the Ozone Layer. Greenhouse is a place which protects Plants from direct sunlight. Greenhouse gases cause many problems which can cause climate change, like melting of the glacier, rise in the sea water and Increase in storms. In the reduction of the greenhouse gases, a number of processes have been started like using renewable energy, using Bicycle, Using local transportations, protecting forests and using air filters.

Transforming polymeric air filters into high-performance supercapacitor electrodes through carbonization and fluorination

The global surge in disposable mask usage during the COVID-19 pandemic raises environmental concerns due to improper disposal. This study proposes an innovative method to repurpose polypropylene (PP) from disposable masks into highly efficient supercapacitor electrodes. Previous attempts faced challenges in electrochemical performance due to high charge transfer resistance. To overcome this, we introduce a unique approach, transforming PP masks into high-performance supercapacitor electrodes through thermal carbonization, activation, and fluorination. PVDF annealing fluorination simultaneously executes these transformations, resulting in a 40 % increase in specific capacitance, from 130.4 F g−1 to 183.3 F g−1. Our electrode materials exhibit remarkable durability, retaining an impressive 90.8 % of their initial capacity even after undergoing 8000 charge-discharge cycles, highlighting exceptional electrochemical performance. The porosity of the fluorinated carbon fibers (FCF) was determined through N2 adsorption at 77 K, revealing a pore volume of 0.5 cm3 g−1 and a specific surface area of 1175 m2 g−1. This study not only repurposes PP from masks but also enhances their electrochemical properties, addressing environmental impact and representing a significant stride in sustainable material development.

Health benefits to vulnerable populations by meeting particle-level guidelines inside schools with different ventilation conditions

ABSTRACT We conducted simultaneous real-time measurements for particles on the premises of four schools, two of which were naturally ventilated (NV) and two mechanically ventilated (MV) in Kanpur, India. Health to school children from reduced particle levels inside classrooms simulated to the lowest acceptable levels (ISHRAE Class C: PM10 ≤ 100 µg/m3 & PM2.5 ≤ 25 µg/m3) using air filters were examined. Lung deposition of particles was used as a proxy for health impacts and calculated using the MPPD model. The particle levels in all classrooms were above the baseline, with NV classrooms having higher particle masses than MV classrooms: 72.16% for PM1, 74.66% for PM2.5, and 85.17% for PM10. Our calculation reveals a whooping reduction in particles deposited in the lungs (1512% for PM10 and 1485% for PM2.5) in the case of the NV classrooms. Results highlight unhealthy air inside classrooms and suggest urgent interventions, such as simple filtration techniques, to achieve acceptable levels of particles inside schools.

Reduction by air purifier of particulate concentration during orthodontic procedures: a pilot study

BackgroundThe SARS-CoV-2 pandemic has raised awareness of the importance of air quality. This pilot study arose from the need to reduce the concentration of particulate matter in the dental office during orthodontic procedures. To evaluate the efficacy of using an air purifier during orthodontic care in the dental office to reduce the concentration of ambient particulate matter.ResultsSignificant reductions in particle numbers were obtained for all particle sizes except the largest particles counted (10 μm) through use of the air filter. A marked association between higher humidity levels and higher particle counts was also observed.ConclusionsUsing an air purifier during dental care achieves a significant reduction in the concentration of ambient particles in the dental office. There is a correlation between higher relative humidity and higher particle concentration. The probability of obtaining a maximum particulate concentration level of 0.3 and 0.5 μm is 1000 times lower when using an air purifier.

Operating Behavior of Pulse Jet‐Cleaned Filters Regarding Energy Demand and Particle Emissions – Part 2: Modeling

AbstractBaghouse filters applied for gas cleaning are subject to digitalization concepts, including process modeling and the development of digital twins in order to improve energy efficiency and lower particle emissions. Modeling equations from literature were adapted to match experimental data from part 1 of this study to calculate the effect of varying filter face velocities, dust concentrations, or tank pressures on energy demand and particle emissions. Based on the model approaches, an operation curve that enables the evaluation of filter operation regarding the trade‐off between energy demand and particle emissions can be constructed. The identification of energetically optimal cycle times and favorable operation regions is possible due to the extensive experimental framework of the model.

Abstract 18: Toll-Like Receptor 4 Knockout Attenuates Microglia-Mediated Oxidative Stress and White Matter Toxicity

Background: Exposure to ambient air pollution causes neuroinflammation and white matter (WM) damage. In patients with preexisting cerebrovascular disease, pollution exposure can compound underlying pathology and may accelerate functional decline. Major mechanisms of this toxicity are microglial reactivity and oxidative stress. We therefore hypothesized that attenuation of the Toll-like receptor 4 (TLR4)-dependent microglial response would significantly decrease oxidative WM damage in a joint experimental model of pollutant exposure and chronic cerebral hypoperfusion modeled by surgical bilateral carotid artery stenosis (BCAS). Methods: Inducible microglial/macrophage-specific TLR4 deletion was achieved using a Tamoxifen-induced Cx3cr1CreER+/- mouse model. Male and female Cx3cr1CreER+/- mice treated with tamoxifen (i-mTLR4-ko) or corn oil (control) were exposed to 120 hours of filtered air (FA) or aerosolized diesel exhaust particulate (DEP), and 30 days of BCAS or sham surgery using a factorial design. The 8 experimental groups were: 1) control/FA (n=10), 2) control/DEP (n=10), 3) control/FA + BCAS (n=9), 4) control/DEP+BCAS (n=10), 5) i-mTLR4-ko/FA (n=9), 6) i-mTLR4-ko/DEP (n=8), 7) i-mTLR4-ko/FA + BCAS (n=8), and 8) i-mTLR4-ko/DEP+BCAS (n=10). Immunofluorescence was used to identify 4-HNE and 8-OHdG expression in the corpus callosum (CC). Results: While control mice showed elevations of 4-HNE in the CC after DEP (p<0.01) and DEP+BCAS (p<0.0001), i-mTLR4-ko prevented this change (Figure 1). While control mice exhibited a rise in 8-OHdG in the CC after DEP+BCAS (p<0.05), i-mTLR4-ko prevented this rise. Conclusions: We demonstrate that i-mTLR4-ko is sufficient to abate major elevations in oxidative stress markers in WM after DEP and BCAS exposures. This suggests a potential role for therapies targeting TLR4 signaling to minimize pollution-associated neurotoxicity, particularly in the setting of cerebral hypoperfusion.

Microglial TLR4 Mediates White Matter Injury in a Combined Model of Diesel Exhaust Exposure and Cerebral Hypoperfusion.

Air pollution particulate matter exposure and chronic cerebral hypoperfusion (CCH) contribute to white matter toxicity through shared mechanisms of neuroinflammation, oxidative stress, and myelin breakdown. Prior studies showed that exposure of mice to joint particulate matter and CCH caused supra-additive injury to corpus callosum white matter. This study examines the role of TLR4 (toll-like receptor 4) signaling in mediating neurotoxicity and myelin damage observed in joint particulate matter and CCH exposures. Experiments utilized a novel murine model of inducible monocyte/microglia-specific TLR4 knockout (i-mTLR4-ko). Bilateral carotid artery stenosis (BCAS) was induced surgically to model CCH. TLR4-intact (control) and i-mTLR4-ko mice were exposed to 8 weeks of either aerosolized diesel exhaust particulate (DEP) or filtered air (FA) in 8 experimental groups: (1) control/FA (n=10), (2) control/DEP (n=10), (3) control/FA+BCAS (n=9), (4) control/DEP+BCAS (n=10), (5) i-mTLR4-ko/FA (n=9), (6) i-mTLR4-ko/DEP (n=8), (7) i-mTLR4-ko/FA+BCAS (n=8), and (8) i-mTLR4-ko/DEP+BCAS (n=10). Corpus callosum levels of 4-hydroxynonenal, 8-Oxo-2'-deoxyguanosine, Iba-1 (ionized calcium-binding adapter molecule 1), and dMBP (degraded myelin basic protein) were assayed via immunofluorescence to measure oxidative stress, neuroinflammation, and myelin breakdown, respectively. Compared with control/FA mice, control/DEP+BCAS mice exhibited increased dMBP (41%; P<0.01), Iba-1 (51%; P<0.0001), 4-hydroxynonenal (100%; P<0.0001), and 8-Oxo-2'-deoxyguanosine (65%; P<0.05). I-mTLR4 knockout attenuated responses to DEP/BCAS for all markers. i-mTLR4-ko markedly reduced neuroinflammation and oxidative stress and attenuated white matter degradation following DEP and CCH exposures. This suggests a potential role for targeting TLR4 signaling in individuals with vascular cognitive impairment, particularly those exposed to substantial ambient air pollution.

Planning of rational use of forest resources in Ukraine based on the improvement of ecosystem services

The study of land conservation methods for forest conservation and restoration is important and relevant from the standpoint of balanced use of natural resources and biodiversity conservation. The purpose of the study was to investigate effective strategies for the exploitation of land with self-forested areas to meet the needs of the agricultural sector of the Zolochiv District of the Lviv Oblast. In the course of the study, the following methods were used: analysis; geographical method; statistical method; cartographic method; geoinformation method. It is worth noting that for the land plot No. 1 within the Buska territorial community of Lviv Oblast, it was recommended to conserve the land, with its subsequent renaturalisation. According to the results of the analysis, it is shown that in 2011 the processes of independent afforestation of agricultural land within the Busk territorial community were insignificant. In 2023, the situation improved, as the area of afforded land increased significantly. To the soils of the land plot No. 2, which was part of the Brody urban community, it was advisable to use conservation and transformation. In the Zolochiv community, 14.2 hectares of land should be rehabilitated, 27.3 hectares should be transformed into pasture, and 3.5 hectares should be alkalised. The paper suggests the introduction of innovative approaches for integrated planning of the use of forest resources: creation of forest farms, development of forest tourism, creation of special forest stands for air filtration, application of bio-refining technology, etc. The findings can be used by local communities to develop and implement a draft of measures for the comprehensive development plan of the territory of the Lviv Oblast to improve forest ecosystem services

A comprehensive analysis of hydrogen fuel cell integration in fishing vessels

HHO gas is a fuel supplement produced through the electrolysis process of water in an HHO generator, where HHO gas falls under the category of alternative energy and is classified as a new energy source. The fundamental principle of internal combustion engines is generally to convert the chemical energy of liquid fuel into mechanical energy. The production of hydrogen through the electrolysis process is continuously evolving to facilitate the use of environmentally friendly fuels, with potential impacts on engine performance and exhaust gas emissions. This study examines the effect of adding HHO gas to electronic fuel injection (EFI) type-L gasoline engines on exhaust gas emissions and fuel consumption. It has been proven that the addition of HHO gas to the combustion process of gasoline engines, particularly EFI type-D, results in reduced emission levels (CO by 15.31% and HC by 16.27%). Moreover, the introduction of 0.1 Mol of HHO gas into EFI type-L engines through the air filter leads to a significant impact on exhaust gas emissions and a 2.8% increase in fuel consumption compared to not using HHO gas. This could be attributed to the distinct characteristics of EFI systems compared to conventional engines, as they are not accustomed to fuel supplements being injected into the engine.

Self-reported health impacts of do-it-yourself air cleaner use in a smoke-impacted community

BackgroundSmoke exposure from wildfires or residential wood burning for heat is a public health problem for many communities. Do-It-Yourself (DIY) portable air cleaners (PACs) are promoted as affordable alternatives to commercial PACs, but evidence of their effect on health outcomes is limited. ObjectivePilot test an evaluation of the effect of DIY PAC usage on self-reported symptoms, and investigate barriers and facilitators of PAC use, among members of a tribal community that routinely experiences elevated concentrations of fine particulate matter (PM2.5) from smoke. MethodsWe conducted studies in Fall 2021 (“wildfire study”; N = 10) and Winter 2022 (“wood stove study”; N = 17). Each study included four sequential one-to-two-week phases: 1) initial, 2) DIY PAC usage ≥8 h/day, 3) commercial PAC usage ≥8 h/day, and 4) air sensor with visual display and optional PAC use. We continuously monitored PAC usage and indoor/outdoor PM2.5 concentrations in homes. Concluding each phase, we conducted phone surveys about participants’ symptoms, perceptions, and behaviors. We analyzed symptoms associated with PAC usage and conducted an analysis of indoor PM2.5 concentrations as a mediating pathway using mixed effects multivariate linear regression. We categorized perceptions related to PACs into barriers and facilitators of use. ResultsNo association was observed between PAC usage and symptoms, and the mediation analysis did not indicate that small observed trends were attributable to changes in indoor PM2.5 concentrations. Small sample sizes hindered the ability to draw conclusions regarding the presence or absence of causal associations. DIY PAC usage was low; loud operating noise was a barrier to use. DiscussionThis research is novel in studying health effects of DIY PACs during wildfire and wood smoke exposures. Such research is needed to inform public health guidance. Recommendations for future studies on PAC use during smoke exposure include building flexibility of intervention timing into the study design.

High-Performance Nanomaterial’s in Air Filtration and Purification

Industrialization and urbanization are amongst the major sources of air pollution. Though high-performance nanomaterials offer compelling advances for air filtration and purification. In this work, several nanomaterials were tested for their ability to remove particulates (PM2.5 and PM10) and VOCs, while evaluating the wear and tear of each material. Pressure had no effect on PM2.5 capture efficiency which was 80% using activated carbon, while carbon nanotubes were more efficient in PM10 capture despite greater pressure drop. Graphene oxide was very effective in the abatement of volatile organic compounds, which was not the case for titanium dioxide which performed as good as activated carbon in the capture of PM2.5 particles but with a pressure drop of the same magnitude. Silver nanoparticles were the most effective in a percent capture of PM10 particles at low pressure drop. Yeoman’s zinc was effective in re-absorbing volatile organic compounds from the dust. The PEI-coated and electro spun nanofibers are capable of capturing PM2.5 and PM10 particles respectively, and at relatively low-pressure reductions. Results from durability studies demonstrated that TiO2 and silver nanoparticles exhibited superior efficiency retention throughout numerous cycles, but PEI-coated nanofibers saw substantial efficiency degradation

Investigation of airborne nanoparticles emitted during the laser cleaning process of corroded metal surface

Laser surface cleaning is a promising surface-cleaning technique owing to its numerous benefits, including its noncontact behavior, ease of control, high precision, and no secondary waste generation. However, it cannot prevent airborne nanoparticle emissions during the laser cleaning process. Therefore, the effects of laser-cleaning parameters on airborne nanoparticle generation are analyzed to design potential remediation methods. In this study, the nanoparticles released during the laser cleaning of corroded 304L stainless steel surfaces were investigated. Electrical low-pressure impactor analysis and electron microscopy were conducted to determine how laser parameters influenced the size and amount of emitted nanoparticles. Based on these findings, the feasibility of the filtering emitted nanoparticles using high-efficiency particulate air filters was examined.

Study on preparation and application comfort of composite personal protective nanofiber filter material for mining

Miner's pneumoconios is a serious global public health problem. To further improve the application performance of individual protective materials, this paper prepared three-layered composite filter material composed of a hydrophobic external layer, a dust filter intermediate layer, and a moisture permeable internal layer, and explored the influence of composite ratio on the comprehensive performance of the filter material. The thermal comfort evaluation index system under complex working conditions environment was established. The results show that the optimal composite ratio of composite filter material is 2/6/2. This optimal composite filter material has dual-structure with high filtration efficiency of 99.9 %, low resistance of 98.7Pa, high quality factor of 0.07 and high air permeability of 364 mm/s. The construction of the wetting gradient realizes the efficient moisture permeability of 11.1 kg·m−1·d−1of the filter media. In addition, it shows the antibacterial activity of over 90 % against S.aureus and E.coli. The ergonomics experiments shows the heart rate and oxygen uptake are the key influencing factors reflecting the thermal comfort of the filter material. The composite filter material developed with excellent air and moisture permeability can provide a comfortable and safe breathing environment under the working environment of high temperature, high humidity and high labor intensity.

Earthworm-inspired mechanical toughened biodegradable polylactic acid microfiber for sustainable air filtration

Fully renewable and biodegradable polylactic acid (PLA) microfiber filters are attractive candidates for traditional unsustainable filters due to their unique advantages of maintaining mechanical strength while in service and rapidly degrading after waste. However, the toughness of sustainable PLA melt-blown microfibers (PLAMFs) with high polymeric chain orientation is poor, which makes it difficult to meet the requirements of air filtration applications. Here, a facile but effective polymeric chain limited domain rearrangement (PLR) strategy inspired by earthworms is developed to toughen PLAMFs. In this process, the short-time and high-temperature heat treatment can quickly break the original hydrogen bonds between polymeric chains and form new ones, which stimulates the thermal movement of polymeric chains from the low entropy position to the high entropy position, resulting in the intrinsically toughening of PLAMFs while maintaining strength. The resulting PLR-PLAMFs and PLR PLA melt-blown nonwovens (PLR-PLAMNs) exhibit enhanced toughness of 146.32 MJ m−3 (an increase of 143.99 %) and 0.80 MJ m−3 (an increase of 66.67 %), respectively. Moreover, toughened PLA melt-blown nonwovens (PLAMNs) after corona electret (CE) treatment exhibit high filtration efficiency (>90.00 % PM0.3 removal) and extremely low pressure drop (<0.02 % atmospheric pressure), which is highly promising for application in sustainable air filtration.