Air pollution has drawn increasing attention. The channel-type structure, as an idealenergy-saving and resistance-reducing strategy for air filters, can effectively lower filtra-tion resistance. However, current commercial channel-type filters generally exhibit onlymedium or low filtration efficiency, and the use of plant fibers as raw material limitstheir application in high-efficiency filters. In this study, high-efficiency glass fiber filterpaper was combined with a channel-type structure, and the formulation and processingtechniques suitable for the channel-type design were systematically investigated, leadingto the fabrication of channel-type high-efficiency filters. The optimal formulation wasdetermined to be a blend of glass wool fibers and 6 mm Tencel fibers in a 6:4 ratio, coatedwith a thermosetting resin, which yielded filter paper suitable for wave-pleating. Theresulting filter paper demonstrated a filtration efficiency of 99.9624%, a pressure drop of265.6 Pa, and a pleat aspect ratio of 0.209. Using this formulation, pilot-scale filter paperwas produced and wave-pleated under processing conditions including a roller speed of5 m/min,a roller gap of 0.4 mm, and a roller temperature of 160 degrees C, which was then usedto fabricate channel-type high-efficiency filters. The finished channel-type filters achieveda filtration efficiency of 99.9940% with a pressure drop of 164.0 Pa. Compared to traditionalpleated filters of the same volume and efficiency rating, the channel-type filter exhibiteda 49.53% larger filtration area, a 33.13% lower face velocity, and a 31.67% reduction inpressure drop. This work offers a novel approach to reducing resistance and enhancingefficiency in air filtration systems.

To satisfy the requirements of channel-type ultra-low penetration air (ULPA) filters for high filtration efficiency, low pressure drop, and good corrugation processability, a three-layer composite filter medium with a bast-fiber surface layer/glass wool-lyocell blended core layer/bast-fiber surface layer structure was designed and prepared. The effects of surface-layer material, core-layer fiber composition, surface-layer basis weight, and processing conditions on the overall performance of the medium were systematically investigated. Bast-fiber paper exhibited the best corrugation processability and mechanical performance and was selected as the surface layer. The optimal core-layer composition was 25 wt.% 475-79 glass wool fibers, 30 wt.% 475-59 glass wool fibers, and 45 wt.% lyocell fibers, yielding an original-sheet filtration efficiency of 99.9996% and a pressure drop of 381 Pa. Further optimization showed that a bast-fiber surface layer with a basis weight of 15 g/m2 provided the best balance among pleat retention, structural stability, and low-resistance characteristics. Under optimized corrugation conditions of 120 °C roller temperature, 10 m/min roller speed, and 0.480 mm roller gap, a desirable pleat morphology suitable for channel-type structures was obtained. The resulting channel-type ULPA filter maintained a filtration efficiency of 99.99954%, while increasing the effective filtration area by 51.6% and reducing the pressure drop by 26.1% compared with a conventional pleated filter with the same dimensions. These results provide a useful reference for the design and application of low-resistance, high-efficiency filter media for channel-type ULPA filters.

Antibacterial filter materials have been effectively utilized for controlling biological contaminants and purifying indoor air, with the market for such materials experiencing continuous expansion. Currently, textile antibacterial testing standards are widely adopted to evaluate the antimicrobial efficacy of filter materials, yet no dedicated assessment protocols specifically tailored for filtration media have been established. This study aims to investigate the applicability of textile antibacterial testing methods to high-efficiency glass fiber filter materials (filtration efficiency > 99.9%), as well as to explore the factors that affect the rate of bacterial elution from high-efficiency glass fiber filter materials. By referencing the textile antibacterial testing standard (absorption method), significant discrepancies in bacterial recovery counts were observed between the high-efficiency glass fiber materials and the various textile control samples, with the former exhibiting a markedly lower recovery rate (approximately 10%). Pore structure and wettability analyses revealed the underlying causes of these differences. To ensure the accuracy of the antibacterial evaluation results, the effects of oscillation elution parameters (time and intensity) and material incubation conditions (duration, sealing and humidity) on bacterial recovery rates in glass fiber filter materials were systematically investigated to optimize the elution methodology. The results indicate that specimen type, size, elution method, incubation duration (4 h or 24 h), sealing conditions, and environmental humidity (10% or 30%, 60% and 95% RH) collectively influence bacterial recovery efficiency. The highest recovery efficiency (55%) was achieved when the filter materials were incubated in a sealed environment with humidity maintained at ≥ 60% RH. These findings emphasize the critical need to establish clear and specialized antibacterial performance testing standards for filter materials. The study provides essential guidance for developing material-specific evaluation protocols to ensure a reliable and standardized assessment of antimicrobial efficacy in high-efficiency filtration systems.

Pleated filter media are widely used in particulate filtration, but the particle deposition and pressure drop during particle loading remain insufficiently explored. This study visualizes the particle deposition patterns in pleated filter media, along with the evolution of pressure drop and the effective filtration area (EFA) using simulations. The results indicate that, as the volume of deposited particles increases, the pressure drop of the pleated filter media initially grows linearly, but this rate of increase accelerates as particle deposition continues. The particle deposition characteristics are related to the pleat ratio. A smaller pleat ratio results in a smaller initial EFA, leading to a high initial resistance growth rate. Conversely, a larger pleat ratio leads to faster aggregation of particles, resulting in a faster rise in the resistance growth rate. The dust-holding capacity is optimal at a pleat ratio of 6.67. When the inlet flow rate or the particle size increases, it is more favorable to reduce the pleat ratio. The reliability of the results is verified using experiments, and the error is within 20%. The findings provide theoretical and practical insights for optimizing the design of pleated filter media for better performance in particulate filtration.

Protection from nuclear biochemical aerosol and air pollution pays attention to aerosol mass concentration. The concentration of upstream aerosol of the commonly used filtration efficiency detection device for high-efficiency filter materials is low, making it insufficient for detecting the filtration efficiency of high-efficiency filter materials. This study designed and built a set of filtration efficiency detection devices for high-efficiency filter materials based on mass concentration. By adjusting the oil bath temperature, injection pressure, the degree of spiral-separator separation, as well as the number and size of nozzles, we investigated the effects of each condition on the concentration and particle size distribution of aerosol generation. As a result, the oil mist generator of the device can stably generate high-concentration aerosol with a mass concentration of up to 1587.9 mg/m3 and a number concentration of up to 107–108 P/cm3. The high-concentration aerosol generated can meet the E11–U15 filter material performance requirements.

Enhancing the antimicrobial activity of high-efficiency particulate air (HEPA) filters while maintaining filtration efficiency and pressure drop is currently an urgent issue for preventing the spread of pathogenic microorganisms. Herein, inspired by vines which can enwind fences to fix as well as decorate them, a flexible antimicrobial chitin nanofiber (ChNF@CuO x ) was fabricated and loaded onto the rigid glass fiber (GF) skeleton of a HEPA filter. Through the physical interaction, ChNF@CuO x was spontaneously enwound on GF, and ChNF@CuO x itself interweaved to form a new nanonetwork between the GF skeleton. The obtained antimicrobial air filter (ChNF@CuO x /GF) with a unique nanonetwork increased the filtration efficiency of the HEPA filter. Meanwhile, it possessed excellent inactivation ability against Staphylococcus aureus, Escherichia coli, and Candida albicans due to the urchin-like in situ grown CuO x on the ChNF. In particular, the oxygen vacancies generated unexpectedly in CuO x enabled it to produce reactive oxygen species. After eight cycles of antimicrobial assays, the antimicrobial rates of bacteria were higher than 99.5%, and those of fungi were greater than 98.3%. The successful synthesis of antimicrobial fibers and the construction of multidimensional nanoscale structures through a simple postprocessing method provide a new design mentality for antimicrobial functionalization for HEPA filters.

The development of high-performance antibacterial agents is crucial for controlling bacterial contamination and water purification, while the easy aggregation of the nanomaterials significantly limits their antibacterial activities. Inspired by the palygorskite nanorods' immobilization effect for nanoparticles and rod-shaped structure and surface-rich groups of cellulose nanocrystals (CNC), we in-situ grew the Cu9S5 nanoparticles on the renewable CNCs of different length/diameter ratios to fabricate cellulose nanocrystal/Cu9S5 (CNC/Cu9S5) antibacterial nanocomposites. The size of Cu9S5 nanoparticles shrank from 44 nm before compounding with CNCs to around 4 nm after in-situ growing on CNCs surface, and the obtained CNC/Cu9S5 nanocomposites with good water dispersibility showed excellent antibacterial properties (CNC-M/Cu9S5: 4.6 log reduction rate of S. aureus) by combining the physical puncture effect of CNC-M and copper ions releasing. Afterward, the antibacterial glass fiber/CNC-M/Cu9S5 microfiltration membrane was constructed by depositing the CNC-M/Cu9S5 on glass fiber microfiltration membrane, which showed high filtration flux, high retention capacity for bacteria and good bactericidal performance (>99.9% sterilization rate for S. aureus), suggesting its great potential for water purification.

Upper-room ultraviolet germicidal irradiation (UVGI) technology can potentially inhibit the transmission of airborne disease pathogens. There is a lack of quantitative evaluation of the performance of the upper-room UVGI for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) airborne transmission under the combined effects of ventilation and UV irradiation. Therefore, this study aimed to explore the performance of the upper-room UVGI system for reducing SARS-CoV-2 virus transmission in a hospital isolation environment. Computational fluid dynamics and virological data on SARS-CoV-2 were integrated to obtain virus aerosol exposure in the hospital isolation environment containing buffer rooms, wards and bathrooms. The UV inactivation model was applied to investigate the effects of ventilation rate, irradiation flux and irradiation height on the upper-room UVGI performance. The results showed that increasing ventilation rate from 8 to 16 air changes per hour (ACH) without UVGI obtained 54.32% and 45.63% virus reduction in the wards and bathrooms, respectively. However, the upper-room UVGI could achieve 90.43% and 99.09% virus disinfection, respectively, with the ventilation rate of 8 ACH and the irradiation flux of 10 μW cm-2. Higher percentage of virus could be inactivated by the upper-room UVGI at a lower ventilation rate; the rate of improvement of UVGI elimination effect slowed down with the increase of irradiation flux. Increase irradiation height at lower ventilation rate was more effective in improving the UVGI performance than the increase in irradiation flux at smaller irradiation height. These results could provide theoretical support for the practical application of UVGI in hospital isolation environments.

At present, the reuse of corn stalk (CS) or other biomass stalk generally requires crushing or dissolution, which leads to waste of energy and use of toxic chemicals. In this work, porous CS was directly utilized without any pretreatment as furniture and building materials by loading silver nanoparticles (AgNPs) and montmorillonite (MMT), which endowed excellent flame retardant and antibacterial properties. Firstly, CS was delignified (DLCS) to expose more porous structures. Then, DLCS was used to in situ reduce and immobilize AgNPs, and MMT particles was further loaded into holes of DLCS to prepare antibacterial and flame-retardant CS (DLCS/MMT/ AgNPs). Due to the oxygen barrier layer formed by MMT in the combustion process, the time DLCS/MMT/AgNPs started combustion delayed to 5 s while that of CS was 1 s. The combustion residue of DLCS/MMT/AgNPs retained after burning under nitrogen and air atmosphere at 800 degrees C were 65.8% and 61%, respectively, and basically maintained its original morphology. Furthermore, AgNPs endowed DLCS/MMT/AgNPs with the inhi-bition zone of 3.5 mm and 2.0 mm for E. coli and S. aureus, respectively, as well as long-lasting antibacterial property for at least 7 days. This work laid a theoretical foundation for agricultural waste CS to realize the high-value utilization in an economical and environmentally friendly way.

Since the outbreak of COVID-19, microbial pollutants in the air have attracted people's attention. Existing air filters can only intercept microorganisms but cannot inactivate them. Thus, there is an urgent need to design air filters with antibacterial properties. In this study, we used vacuum-assisted filtration to adjust the pore structure of the traditional glass fiber air filter with cellulose nanofiber (CNF) and tempo-oxidized nanocellulose (TNF), and constructed a graded air filter (GCT) with gradient pore structure and Janus structure. At the same time, the addition of nanofibers increased the mechanical properties of the glass fiber air filter. Finally, the filters were endowed with good photothermal properties and stable antibacterial properties by adding antibacterial agents from previous studies (GCT/Ag-3). GCT/Ag-3 responded under near-infrared light, achieving a 99.9 % antibacterial rate against E. coli and S. aureus within 90s, and maintaining this high efficiency after 6 cycles, which provides a feasibility for the design of antibacterial air filter.

为研究蒸发冷凝式气溶胶多分散性对滤料透过率试验的影响程度,分别测试了从低效到高效多种滤料在不同过滤速度、不同粒数中值粒径下的透过率.通过修正计算得到典型过滤速度下的真实透过率曲线,与试验透过率对比发现:最易穿透粒径全部位于0.1～0.3 μm;试验测得最易穿透粒径呈负偏差,与修正后的数值相对误差小,最大不超过1.5％;试验气溶胶多分散性导致的透过率误差极值出现在最易穿透粒径处,呈负偏差,低效滤料相对误差较小,极值最低为2.4％,高效滤料极值最大约为10％.因此,在最易穿透粒径范围附近,蒸发冷凝式单分散试验气溶胶测出的最易穿透粒径和透过率是真实有效的.

In this study, the photocatalytic chlorine-radical-mediated reaction dramatically enhanced the catalytic activity of TiO2 for ozone removal, which was different from traditional photocatalytic mechanism driven by hydroxyl radicals. Chlorinated TiO2 was prepared using the sol-gel method and modified through surface chlorination. The ozone-removal efficiency was up to 99.9% over the chlorinated TiO2 under UV light, which was 2.5 times that of bare TiO2. Moreover, experiments also showed that chlorinated TiO2 possessed excellent water-resistance and reusability. Characterization results unveiled that the chlorine is attached to the surface of TiO2 in the form of Ti–Cl bonds, which can capture holes to form·Cl. Subsequently, it was proven that the chain transfer reaction initiated by·Cl was mainly responsible for the remarkable improvement in the photocatalytic conversion of ozone. This new photocatalytic mechanism driven by chlorine radical opens up a new field of ozone removal by photocatalysis.

利用溶胶凝胶法制备了 BiOBr/TiO2复合型光催化剂并进行氯化改性,紫外照射下表现出了较高的臭氧转化能力.随后利用XRD、UV-Vis DRS、TEM、EPR、电化学等方法对催化材料进行表征,分析其光催化反应原理.结果表明,BiOBr/TiO2对臭氧的转化率提升至61％,这是由于二者形成了半导体异质结,光生电子传递降低了载流子复合率,羟基自由基生成量增加;氯化材料的转化率进一步大幅提升至99％,这是由于氯元素在光照条件下生成氯自由基,进而驱动了一种效率更高的链式传递反应.该反应体系在较高湿度下未见明显失活,优于传统α-MnO2,具有应用潜力.

基于半导体异质结原理,设计并制备了新型氯氧铋/二氧化钛复合光催化材料,以甲基橙为目标污染物,研究了氯氧铋制备条件和复合比例对复合材料的光催化特性的影响,随后利用XRD、UV-Vis DRS、TEM、EPR等方法对催化材料进行表征,从表面形貌、自由基等角度,分析其光催化原理.结果 表明,新型复合光催化材料相对氟氧铋、二氧化钛的单体,具有更强的紫外催化能力,对传统有色染料均具有良好的去除效果.这是由于氯氧铋和二氧化钛可以形成半导体异质结,光生电子传递降低了载流子负荷率,羟基自由基生成量增加,因此光催化性能大幅提升.

本文利用溶胶凝胶法制备了溴氧铋/二氧化钛复合光催化材料.以甲基橙为目标污染物,研究了溴氧铋含量对复合材料的可见光催化特性的影响,随后通过表面氯化改性,进一步提升了光催化能力.最后利用XRD、UV-Vis DRS、TEM、EPR等方法对催化材料进行表征,分析其光激发原理.结果表明,新型复合材料具有较好的可见光响应,对有机物的降解能力优于溴氧铋和二氧化钛单体,这是由于二者形成了半导体异质结,光生电子传递降低了载流子复合率,羟基自由基生成量增加,而表面氯化引入了新的氯自由基,进一步提高反应活性.

采用溶胶凝胶法制备了 BiOCl/TiO2复合催化剂,透射电镜(TEM)照片显示,两种半导体分布均匀、相互连接,形成的异质结可以为电子传导提供有效通道.经过氯化处理的复合材料具备更强的光催化能力,在紫外光条件下对苯的降解率达到90％,是原BiOCl/TiO2的 2倍、纯TiO2的10倍.本文利用X射线光电子能谱、红外光谱和电子顺磁共振,对表面氯化的机理进行研究.结果表明,氯元素以Ti—Cl的方式吸附在催化剂表面,在光照条件下光生空穴夺取一个电子,使其生成氯自由基,进而配合超氧、羟基,构成一种新型的三自由基光催化体系,使催化降解能力大幅提升.最后,利用实验方法得到了光生氯自由基的直接证据,并构建了该体系的光催化反应机理.

成功制备了一系列石墨烯/TiO2复合材料并分别氯化改性.以甲基橙和苯酚作为目标污染物,进行复合材料光催化降解活性实验;随后引入电化学和电子顺磁共振技术对该催化剂及其反应体系进行表征,推断其机理.结果表明,石墨烯具有极好的电子迁移能力,可以提高光生载流子的传递效率,进而增强TiO2紫外催化性能.新型复合材料均表现出较高的光催化降解活性,甲基橙降解率由70％提升至100％,苯酚降解率由10％提升至100％.而表面氯化引入了新的活性基团,在光照条件下能够生成氯自由基,进而配合羟基、超氧,形成一种新的三自由基反应体系,使其氧化降解能力大幅提升.

Environmentally friendly cellulose/GO/TiO2 hydrogel photocatalyst has been successfully fabricated via a green, simple, and one-step method and evaluated as the photocatalyst and adsorbent for the removal of methylene blue (MB). The XRD and FTIR analysis suggested the strong interaction among cellulose, GO and TiO2, resulting from the formation of hydrogen bonds. Due to the unique porous structure of cellulose hydrogel and introduction of GO, the cellulose/GO/TiO2 hydrogel showed superior (degradation ratio ∼ 93%) and reproducible (no significant change during the ten consecutive cycles) performance in the removal of MB under UV light. Consequently, the prepared cellulose/GO/TiO2 hydrogel can be applied as an eco-friendly, high-performance, reproducible, and stable photocatalyst and adsorbent for the removal of MB. This green hydrogel is a promising candidate for dye wastewater treatment. Moreover, this work is expected to extend the scope of bio-templated synthesis of other nanomaterials for various applications.

为了深入分析染毒环境,我们基于毒气泄漏典型染毒扩散模型,计算了以氯气泄漏为例通常条件下空气污染浓度和伤害区域分布,结合探讨我国代表性重大毒气泄漏事件时发现,目前专用于染毒环境下应急救援的防护措施仅限于个体防护装备,其有限的防护时间严重制约了救援处置的能力,据此本文提出一种集体防护形式-机动防护平台的防护方案,用作救援人员进出染毒区和在染毒核心区处置时的安全无毒庇护所,分析并指出了机动防护平台的任务剖面、所应具有的功能、系统组成、工作方式和原理,为该装备的研制、防护性能评价以及救援中的使用提供了理论依据.