Vishal R. Dharaiya, V. Malyan, Vikas Kumar, M. Sahu, C. Venkatraman, P. Biswas, K. Yadav, Deeksha Haswani, R. S. Raman, Ruqia Bhat, Tanveer Ahmad Najar, A. Jehangir, R. Patil, G. Pandithurai, S. Duhan, Jitendra Singh Laura
Air quality is a global concern, with particulate matter receiving considerable attention due to its impact on human health and climate change. Recent advances in low-cost sensors allow their deployment in large number to measure spatio-temporal and real-time air quality data. Low-cost sensors need careful evaluation with both regulatory approved methods and other data sets to understand their efficacy. In this work, PM concentrations measured by deploying low-cost sensors at four regional sites are evaluated through comparison with satellite-based model MERRA-2 and the SASS reference instrument. Daily PM2.5 mass concentration variation was analyzed at four regional sites of India from January 2020 to July 2020, including pre-lockdown and six different lockdown periods. Higher PM2.5 concentration was observed at Rohtak (119 mu g m-3) compared to Mahabaleshwar (33 mu g m-3), Bhopal (45 mu g m-3) and Kashmir sites during the pre-lock down period. During the lockdown period, the PM2.5 mass concentration was reduced significantly compared to the pre-lockdown period at every location, although the PM2.5 concentration was different at each location. The air quality trend was quite similar in both the measurements, however, MERRA-2 reconstructed PM2.5 was significantly lower in the pre-lockdown period compared to the lockdown periods. Significant differences were observed between low-cost sensor measurements and MERRA-2 reanalysis data. These are attributed to the MERRA-2 modelling analysis that measures less PM2.5 concentration as compared to ground-based measurements, whereas low-cost sensor are and biases.
空气质量是一个全球关注的问题，颗粒物因其对人类健康和气候变化的影响而受到相当大的关注。低成本传感器的最新进展使其能够大量部署以测量时空和实时空气质量数据。低成本传感器需要通过监管机构批准的方法和其他数据集进行仔细评估，以了解其功效。在这项工作中，通过与基于卫星的MERRA-2模型和SASS参考仪器进行比较，评估了在四个区域站点部署低成本传感器测量的PM浓度。分析了2020年1月至2020年7月印度四个区域站点的PM2.5质量浓度日变化，包括封城前和六个不同的封城时期。在封锁前期间，罗赫塔克的PM2.5浓度(119 μ g -3)高于马哈巴利什瓦尔(33 μ g -3)、博帕尔(45 μ g -3)和克什米尔地区。封锁期间各地点PM2.5质量浓度均较封锁前显著降低，但各地点PM2.5浓度存在差异。两项测量的空气质量趋势非常相似，但MERRA-2重建的PM2.5在封城前明显低于封城后。在低成本传感器测量和MERRA-2再分析数据之间观察到显著差异。这要归功于MERRA-2模型分析，与地面测量相比，它测量的PM2.5浓度更低，而低成本的传感器存在误差。
{"title":"Evaluating the Performance of Low-cost PM Sensors over Multiple COALESCE Network Sites","authors":"Vishal R. Dharaiya, V. Malyan, Vikas Kumar, M. Sahu, C. Venkatraman, P. Biswas, K. Yadav, Deeksha Haswani, R. S. Raman, Ruqia Bhat, Tanveer Ahmad Najar, A. Jehangir, R. Patil, G. Pandithurai, S. Duhan, Jitendra Singh Laura","doi":"10.4209/aaqr.220390","DOIUrl":"https://doi.org/10.4209/aaqr.220390","url":null,"abstract":"Air quality is a global concern, with particulate matter receiving considerable attention due to its impact on human health and climate change. Recent advances in low-cost sensors allow their deployment in large number to measure spatio-temporal and real-time air quality data. Low-cost sensors need careful evaluation with both regulatory approved methods and other data sets to understand their efficacy. In this work, PM concentrations measured by deploying low-cost sensors at four regional sites are evaluated through comparison with satellite-based model MERRA-2 and the SASS reference instrument. Daily PM2.5 mass concentration variation was analyzed at four regional sites of India from January 2020 to July 2020, including pre-lockdown and six different lockdown periods. Higher PM2.5 concentration was observed at Rohtak (119 mu g m-3) compared to Mahabaleshwar (33 mu g m-3), Bhopal (45 mu g m-3) and Kashmir sites during the pre-lock down period. During the lockdown period, the PM2.5 mass concentration was reduced significantly compared to the pre-lockdown period at every location, although the PM2.5 concentration was different at each location. The air quality trend was quite similar in both the measurements, however, MERRA-2 reconstructed PM2.5 was significantly lower in the pre-lockdown period compared to the lockdown periods. Significant differences were observed between low-cost sensor measurements and MERRA-2 reanalysis data. These are attributed to the MERRA-2 modelling analysis that measures less PM2.5 concentration as compared to ground-based measurements, whereas low-cost sensor are and biases.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70295226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Air filters are widely used in residential and industrial applications. It is designed to remove particulate pollutants in the air to supply cleaner air to either occupants or industrial equipment. Without air filters, the occupants might suffer from polluted air, and expensive industrial equipment could be damaged by contaminants. However, air filters are installed and operated with a limited performance monitoring system
{"title":"Smart Filter Performance Monitoring System","authors":"Chenxing Pei, Weiqi Chen, Qisheng Ou, D. Pui","doi":"10.4209/aaqr.220416","DOIUrl":"https://doi.org/10.4209/aaqr.220416","url":null,"abstract":"Air filters are widely used in residential and industrial applications. It is designed to remove particulate pollutants in the air to supply cleaner air to either occupants or industrial equipment. Without air filters, the occupants might suffer from polluted air, and expensive industrial equipment could be damaged by contaminants. However, air filters are installed and operated with a limited performance monitoring system","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70295248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aggregated nanoparticle structures are quite ubiquitous in aerosol and colloidal science, specifically in nanoparticle synthesis systems such as combustion processes where coagulation results in the formation of fractal-like structures. In addition to their size, morphology of the particles also plays a key role in defining various physicochemical properties. Electron microscopy based images are the most commonly used tools in visualizing these aggregates, and prediction of the 3-dimensional structures from the microscopic images is quite complex. Typically, 2-dimensional features from the images are compared to available structures in a database or regression equations are used to predict 3-dimensional morphological parameters including fractal dimension and pre-exponential factor. In this study, we propose a combination of evolutionary algorithm and forward tuning model to predict the best fit 3-dimensional structures of aggregates from their projection images. 2-dimensional features from a projection image are compared to the candidate projections generated using FracVAL code and optimized using Particle Swarm Optimization to obtain the 3-dimensional structure of the aggregate. Various 3-dimensional properties including hydrodynamic diameter and mobility diameter of the retrieved structures are then compared with the properties of the aggregate used to form the candidate projection image, to test the suitability of the algorithm. Results show that the hybrid algorithm can closely predict the 3-dimensional structures from the projection images with less than 10% difference in the predicted 3-dimensional properties including mobility diameter and radius of gyration.
{"title":"A Hybrid Particle Swarm Optimization-Tuning Algorithm for the Prediction of Nanoparticle Morphology from Microscopic Images","authors":"Abhishek Singh, T. Thajudeen","doi":"10.4209/aaqr.220453","DOIUrl":"https://doi.org/10.4209/aaqr.220453","url":null,"abstract":"Aggregated nanoparticle structures are quite ubiquitous in aerosol and colloidal science, specifically in nanoparticle synthesis systems such as combustion processes where coagulation results in the formation of fractal-like structures. In addition to their size, morphology of the particles also plays a key role in defining various physicochemical properties. Electron microscopy based images are the most commonly used tools in visualizing these aggregates, and prediction of the 3-dimensional structures from the microscopic images is quite complex. Typically, 2-dimensional features from the images are compared to available structures in a database or regression equations are used to predict 3-dimensional morphological parameters including fractal dimension and pre-exponential factor. In this study, we propose a combination of evolutionary algorithm and forward tuning model to predict the best fit 3-dimensional structures of aggregates from their projection images. 2-dimensional features from a projection image are compared to the candidate projections generated using FracVAL code and optimized using Particle Swarm Optimization to obtain the 3-dimensional structure of the aggregate. Various 3-dimensional properties including hydrodynamic diameter and mobility diameter of the retrieved structures are then compared with the properties of the aggregate used to form the candidate projection image, to test the suitability of the algorithm. Results show that the hybrid algorithm can closely predict the 3-dimensional structures from the projection images with less than 10% difference in the predicted 3-dimensional properties including mobility diameter and radius of gyration.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70295724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sheng-Chieh Chen, Qingfeng Cao, T. Kuehn, Charles Lo, M. Sahu, Y. S. Mayya, D. Pui
High concentrations of ambient particulate matter (PM) have caused millions of premature deaths annually worldwide. The source control strategy was normally implemented to bring the PM pollution down to meet the standards. However, it took more than 50 years for UK and US. As PM pollution is hurting people’s health on daily basis in many countries, a fast and inexpensive control technology should be developed to remedy the slow pace of source control. It should be applied in highly polluted areas, e
{"title":"Design of a Medium Scale Ambient PM2.5 Cleaning System","authors":"Sheng-Chieh Chen, Qingfeng Cao, T. Kuehn, Charles Lo, M. Sahu, Y. S. Mayya, D. Pui","doi":"10.4209/aaqr.220437","DOIUrl":"https://doi.org/10.4209/aaqr.220437","url":null,"abstract":"High concentrations of ambient particulate matter (PM) have caused millions of premature deaths annually worldwide. The source control strategy was normally implemented to bring the PM pollution down to meet the standards. However, it took more than 50 years for UK and US. As PM pollution is hurting people’s health on daily basis in many countries, a fast and inexpensive control technology should be developed to remedy the slow pace of source control. It should be applied in highly polluted areas, e","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70295900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sheng Xiang, Shaojun Zhang, Yu Ting Yu, Hui Wang, Ye Deng, Qinwen Tan, Zi-hang Zhou, Ye Wu
Regulation has been applied to the fine particles (PM 2.5 ) but not to particle number concentrations (PNC). We use a mobile platform to measure PNC and PM 2.5 in four microenvironments (diesel plume, urban freeway, urban street, and rural freeway). A total of 38661 pairs of measurements in two years (winter 2018 and autumn 2020) are used to evaluate variability in the pollutant concentrations and their interrelationships. Source-discerned total PNC ( PNC tot ) and temporal-adjusted PM 2.5 ( ∆ PM 2.5 ) are calculated and evaluated. Results showed that the average PNC tot in winter (4.8 × 10 4 pt cm –3 ) were over two times higher than autumn (0.36 × 10 4 –0.56 × 10 4 pt cm –3 ). Moreover, the traffic emissions ( PNC d,tr ) contribute 30% of the PNC throughout the study while solid fuel burning ( PNC d,sfb ) could be a major contributor only in winter (29%). Seasonal variability in PNC d,tr and PNC d,sfb was found, with 2–3 times higher median PNC d,tr and 7 times higher median PNC d,sfb in winter compared to autumn. Similarly, PM 2.5 in winter (109 µ g m –3 ) was 3–5 times higher than autumn, while ∆ PM 2.5 (40 µ g m –3 ) was 3–6 times higher. In winter, the PM 2.5 and ∆ PM 2.5 showed higher concentrations in urban street and rural freeway similar to PNC d,sfb but opposite to the trend of PNC tot and PNC d,tr . The correlation coefficient (R 2 ) is investigated as three combinations (i.e., PNC tot vs. PM 2.5 , PNC d,tr vs. ∆ PM 2.5 , PNC d,sfb vs. ∆ PM 2.5 ). Here, the R 2 showed a comparable seasonal trend (winter lower than autumn) and similar magnitude as the literature, but no strong correlation (R 2 < 0.15) was found. This stresses the fact that mitigation measures of PM 2.5 do not necessarily reduce PNC and monitoring networks evaluate PM 2.5 exposure are unlikely to represent PNC exposure. The concentration ratios in the three combinations are found to vary with microenvironments and seasons. This variability implies that control policies should be diversified with pollutant types and energy usage of the city.
法规适用于细颗粒(PM 2.5)，但不适用颗粒数浓度(PNC)。我们使用移动平台测量四种微环境(柴油羽流、城市高速公路、城市街道和农村高速公路)中的PNC和PM 2.5。在两年内(2018年冬季和2020年秋季)共使用38661对测量值来评估污染物浓度的变异性及其相互关系。计算和评估来源识别的总PNC (PNC tot)和时间调整的PM 2.5(∆PM 2.5)。结果表明:冬季平均PNC (4.8 × 10.4 pt cm -3)比秋季(0.36 × 10.4 ~ 0.56 × 10.4 pt cm -3)高出2倍以上;此外，在整个研究过程中，交通排放(PNC d,tr)贡献了30%的PNC，而固体燃料燃烧(PNC d,sfb)仅在冬季可能是主要贡献者(29%)。PNC d、tr和PNC d、sfb均存在季节差异，冬季PNC d、tr中值较秋季高2 ~ 3倍，PNC d、sfb中值较秋季高7倍。冬季PM 2.5(109µg m -3)是秋季的3-5倍，∆PM 2.5(40µg m -3)是秋季的3-6倍。冬季，城市街道和农村高速公路的pm2.5和∆PM 2.5浓度较高，与PNC d、sfb相似，但与PNC t、PNC d、tr相反。相关系数(r2)以三种组合(即PNC tot vs. PM 2.5, PNC d,tr vs.∆PM 2.5, PNC d,sfb vs.∆PM 2.5)进行研究。这里的r2表现出与文献相似的季节趋势(冬季低于秋季)和幅度，但没有发现强相关(r2 < 0.15)。这强调了这样一个事实，即pm2.5缓解措施不一定会减少PNC，评估pm2.5暴露的监测网络不太可能代表PNC暴露。三种组合的浓度比随微环境和季节的变化而变化。这种可变性意味着控制政策应该根据城市的污染物类型和能源使用情况而多样化。
{"title":"Evaluating Ultrafine Particles and PM2.5 in Microenvironments with Health Perspectives: Variability in Concentrations and Pollutant Interrelationships","authors":"Sheng Xiang, Shaojun Zhang, Yu Ting Yu, Hui Wang, Ye Deng, Qinwen Tan, Zi-hang Zhou, Ye Wu","doi":"10.4209/aaqr.230046","DOIUrl":"https://doi.org/10.4209/aaqr.230046","url":null,"abstract":"Regulation has been applied to the fine particles (PM 2.5 ) but not to particle number concentrations (PNC). We use a mobile platform to measure PNC and PM 2.5 in four microenvironments (diesel plume, urban freeway, urban street, and rural freeway). A total of 38661 pairs of measurements in two years (winter 2018 and autumn 2020) are used to evaluate variability in the pollutant concentrations and their interrelationships. Source-discerned total PNC ( PNC tot ) and temporal-adjusted PM 2.5 ( ∆ PM 2.5 ) are calculated and evaluated. Results showed that the average PNC tot in winter (4.8 × 10 4 pt cm –3 ) were over two times higher than autumn (0.36 × 10 4 –0.56 × 10 4 pt cm –3 ). Moreover, the traffic emissions ( PNC d,tr ) contribute 30% of the PNC throughout the study while solid fuel burning ( PNC d,sfb ) could be a major contributor only in winter (29%). Seasonal variability in PNC d,tr and PNC d,sfb was found, with 2–3 times higher median PNC d,tr and 7 times higher median PNC d,sfb in winter compared to autumn. Similarly, PM 2.5 in winter (109 µ g m –3 ) was 3–5 times higher than autumn, while ∆ PM 2.5 (40 µ g m –3 ) was 3–6 times higher. In winter, the PM 2.5 and ∆ PM 2.5 showed higher concentrations in urban street and rural freeway similar to PNC d,sfb but opposite to the trend of PNC tot and PNC d,tr . The correlation coefficient (R 2 ) is investigated as three combinations (i.e., PNC tot vs. PM 2.5 , PNC d,tr vs. ∆ PM 2.5 , PNC d,sfb vs. ∆ PM 2.5 ). Here, the R 2 showed a comparable seasonal trend (winter lower than autumn) and similar magnitude as the literature, but no strong correlation (R 2 < 0.15) was found. This stresses the fact that mitigation measures of PM 2.5 do not necessarily reduce PNC and monitoring networks evaluate PM 2.5 exposure are unlikely to represent PNC exposure. The concentration ratios in the three combinations are found to vary with microenvironments and seasons. This variability implies that control policies should be diversified with pollutant types and energy usage of the city.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70296974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we explored the chemical composition and mixing state of fine atmospheric particles in Yinchuan between December 21 and 31, 2021. For this, the single-particle aerosol mass spectrometry (SPAMS) technique was used. Black carbon particles were found to be the predominant aerosol type (in terms of number fraction) throughout the sampling period, accounting for 61.15% of all sampled particles. Considerable changes were noted in the mixing state of the fine particles in the study area. Furthermore, prominent mass spectrum characteristics of potassium particles were observed. The 39 K + signal in the positive mass spectrum was stronger than the other signals. Throughout the sampling process, K-rich and potassium-elemental carbon (KEC) particles accounted for 25.86% and 13.05% of all sampled particles, respectively, followed by OC and NaKEC, which accounted for 12.32% and 11.45%, respectively. With time, complex processes of aerosol concentration variation detected by SPAMS were observed. The number fractions of elemental carbon/organic carbon (ECOC) and KEC particles were significantly higher on polluted days than on clean days. ECOC and KEC particles were more mixed with sulfate and nitrate than EC and NaKEC particles. Compared with clean days, the particle size of each BC particle increased on polluted days. Furthermore, ECOC and KEC particles had larger particle sizes and stronger sulfate and nitrate signals than EC and NaKEC particles, which indicates that ECOC and KEC particles were mostly formed during the aging process. Local pollution events were associated with primary combustion emission and secondary particle generation.
{"title":"Chemical Composition and Mixing State of Fine Particles during Haze Periods in Yinchuan","authors":"Kangning Li, Yanqiu Ma, Liukun Li, Bin Huang","doi":"10.4209/aaqr.230116","DOIUrl":"https://doi.org/10.4209/aaqr.230116","url":null,"abstract":"In this study, we explored the chemical composition and mixing state of fine atmospheric particles in Yinchuan between December 21 and 31, 2021. For this, the single-particle aerosol mass spectrometry (SPAMS) technique was used. Black carbon particles were found to be the predominant aerosol type (in terms of number fraction) throughout the sampling period, accounting for 61.15% of all sampled particles. Considerable changes were noted in the mixing state of the fine particles in the study area. Furthermore, prominent mass spectrum characteristics of potassium particles were observed. The 39 K + signal in the positive mass spectrum was stronger than the other signals. Throughout the sampling process, K-rich and potassium-elemental carbon (KEC) particles accounted for 25.86% and 13.05% of all sampled particles, respectively, followed by OC and NaKEC, which accounted for 12.32% and 11.45%, respectively. With time, complex processes of aerosol concentration variation detected by SPAMS were observed. The number fractions of elemental carbon/organic carbon (ECOC) and KEC particles were significantly higher on polluted days than on clean days. ECOC and KEC particles were more mixed with sulfate and nitrate than EC and NaKEC particles. Compared with clean days, the particle size of each BC particle increased on polluted days. Furthermore, ECOC and KEC particles had larger particle sizes and stronger sulfate and nitrate signals than EC and NaKEC particles, which indicates that ECOC and KEC particles were mostly formed during the aging process. Local pollution events were associated with primary combustion emission and secondary particle generation.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70297685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiyoon Shin, Kyungil Cho, Yoonkyeong Ha, Giwon Kang, Jihye Park, Hunkwan Park, Changhyuk Kim
Airborne molecular contaminants (AMCs) in cleanrooms should be monitored and controlled tightly to reduce yield loss since they can be converted into nanoparticles or surface haze contamination on semiconductor chips or masks. Soft X-ray radiolysis was developed to detect AMCs as low as the ppt-level by forming secondary aerosols from AMCs under soft X-ray irradiation. However, new particle formation (NPF) using soft X-ray radiolysis has not been well investigated. In this study, we have developed a continuous flow tube reactor to understand NPF from AMCs using soft X-ray radiolysis. The reactor was designed to continuously maintain parabolic laminar flows within the tube reactor and to extend the exposure time of the gas molecules to soft X-rays by increasing the number of reactor modules. With the increase in the concentration of sulfur dioxide (SO 2 ), the size distribution of particles formed by soft X-ray radiolysis also showed enhanced NPF and subsequent particle growth. However, the conversion rates of SO 2 into particles decreased simultaneously. The NPF and subsequent particle growth in the reactor were also positively affected by the exposure time to soft X-rays and the residence time. The exposure time was controlled by the number of soft X-ray emitters, and the residence time in the reactor was adjusted by the number of reactor modules and the inlet flow rate. The mixture of ammonia (NH 3 ) with SO 2 stabilized the nucleation of particles formed from SO 2 but suppressed the particle growth. In contrast, nitrogen dioxide (NO 2 ) suppressed both nucleation and growth of particles formed from SO 2 . Among the parameters for controlling soft X-ray radiolysis, the soft X-ray intensity had the highest effect on the inorganic AMCs-to-nanoparticle conversion
{"title":"Characterization of New Particle Formation in Soft X-ray Radiolysis Reactor: AMCs-to-Secondary Inorganic Aerosols","authors":"Jiyoon Shin, Kyungil Cho, Yoonkyeong Ha, Giwon Kang, Jihye Park, Hunkwan Park, Changhyuk Kim","doi":"10.4209/aaqr.220373","DOIUrl":"https://doi.org/10.4209/aaqr.220373","url":null,"abstract":"Airborne molecular contaminants (AMCs) in cleanrooms should be monitored and controlled tightly to reduce yield loss since they can be converted into nanoparticles or surface haze contamination on semiconductor chips or masks. Soft X-ray radiolysis was developed to detect AMCs as low as the ppt-level by forming secondary aerosols from AMCs under soft X-ray irradiation. However, new particle formation (NPF) using soft X-ray radiolysis has not been well investigated. In this study, we have developed a continuous flow tube reactor to understand NPF from AMCs using soft X-ray radiolysis. The reactor was designed to continuously maintain parabolic laminar flows within the tube reactor and to extend the exposure time of the gas molecules to soft X-rays by increasing the number of reactor modules. With the increase in the concentration of sulfur dioxide (SO 2 ), the size distribution of particles formed by soft X-ray radiolysis also showed enhanced NPF and subsequent particle growth. However, the conversion rates of SO 2 into particles decreased simultaneously. The NPF and subsequent particle growth in the reactor were also positively affected by the exposure time to soft X-rays and the residence time. The exposure time was controlled by the number of soft X-ray emitters, and the residence time in the reactor was adjusted by the number of reactor modules and the inlet flow rate. The mixture of ammonia (NH 3 ) with SO 2 stabilized the nucleation of particles formed from SO 2 but suppressed the particle growth. In contrast, nitrogen dioxide (NO 2 ) suppressed both nucleation and growth of particles formed from SO 2 . Among the parameters for controlling soft X-ray radiolysis, the soft X-ray intensity had the highest effect on the inorganic AMCs-to-nanoparticle conversion","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70295266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study performed surface treatment of Flumex, polyimide, and membrane-covered aramid (chosen as test substrates) by the C8-1833 water-repellent agent. Five key parameters (C8-1833 concentration, impregnation time, rolling residue rate, baking temperature, and baking time) were selected to investigate their effects on the filter media’s water-repellent grade and air permeability variation rate. Through an orthogonal optimization test, the optimal water-repellent process parameters were determined. Air and dust filter media test beds were employed to assess the anti-paste bag performance of water-repellent and membrane-covered filter media under high-humidity conditions. The results indicate that the water-repellent grade of the filter media was unaffected by the baking time during complete drying. At water- repellent agent concentrations of no less than 30 g L-1, impregnation times exceeding 3 s, baking temperatures exceeding 240℃, and rolling residue rates below 46%, both filter materials achieved a water-repellent grade 8. Under optimized processing conditions, the water-repellent grade of the filter media reached 8, and the contact angle was maximized, significantly enhancing the hydrophobicity. Both water-repellent and membrane-covered filter media delayed wet dust adhesion. However, in excessively high humidity of flue gas, sustained filtration performance of the filter media might not be achievable. In bag sticking or rapid condensation situations, the water-repellent filter material should be initially dried using high-temperature flue gas and subsequently restores its filtration performance through thorough dust cleaning.
本研究使用C8-1833拒水剂对Flumex、聚酰亚胺和膜覆盖芳纶(选择作为测试底物)进行表面处理。选择5个关键参数(C8-1833浓度、浸渍时间、滚渣率、焙烧温度、焙烧时间)考察其对滤料拒水等级和透气性变化率的影响。通过正交优化试验，确定了最佳拒水工艺参数。采用空气和粉尘过滤介质试验台，对高湿条件下防水性和膜覆盖过滤介质的防膏袋性能进行了评价。结果表明，在完全干燥过程中，滤料的防水性不受烘烤时间的影响。在防水剂浓度不低于30 g L-1、浸渍时间超过3 s、烘烤温度超过240℃、轧制残留率低于46%的条件下，两种过滤材料的防水性均达到8级。在优化的工艺条件下，滤料的防水性达到8级，接触角最大，疏水性显著增强。防水和膜覆盖的过滤介质延迟湿灰尘粘附。然而，在过高湿度的烟气中，过滤介质的持续过滤性能可能无法实现。在粘袋或快速凝结的情况下，防水过滤材料应首先使用高温烟气干燥，然后通过彻底的除尘恢复其过滤性能。
{"title":"Anti-paste Bag Performance of Water-repellent Filter Media in High-humidity Environments Considering Ultra-low Emissions","authors":"Zhongkai Yu, Erbao Guo, Xingcheng Liu, Yuemin Li","doi":"10.4209/aaqr.230148","DOIUrl":"https://doi.org/10.4209/aaqr.230148","url":null,"abstract":"This study performed surface treatment of Flumex, polyimide, and membrane-covered aramid (chosen as test substrates) by the C8-1833 water-repellent agent. Five key parameters (C8-1833 concentration, impregnation time, rolling residue rate, baking temperature, and baking time) were selected to investigate their effects on the filter media’s water-repellent grade and air permeability variation rate. Through an orthogonal optimization test, the optimal water-repellent process parameters were determined. Air and dust filter media test beds were employed to assess the anti-paste bag performance of water-repellent and membrane-covered filter media under high-humidity conditions. The results indicate that the water-repellent grade of the filter media was unaffected by the baking time during complete drying. At water- repellent agent concentrations of no less than 30 g L-1, impregnation times exceeding 3 s, baking temperatures exceeding 240℃, and rolling residue rates below 46%, both filter materials achieved a water-repellent grade 8. Under optimized processing conditions, the water-repellent grade of the filter media reached 8, and the contact angle was maximized, significantly enhancing the hydrophobicity. Both water-repellent and membrane-covered filter media delayed wet dust adhesion. However, in excessively high humidity of flue gas, sustained filtration performance of the filter media might not be achievable. In bag sticking or rapid condensation situations, the water-repellent filter material should be initially dried using high-temperature flue gas and subsequently restores its filtration performance through thorough dust cleaning.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136258287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Weijia Ren, Qifeng Xin, Zhesheng Hua, Zhong Zheng, Lifeng Xiao, Shaojun Liu, Chenghang Zheng, Yang Yang
Zeolite X was synthesized from fly ash under optimized conditions, which was supported with Mn, Ce, and Mn-Ce respectively. Fly ash-derived zeolite X catalysts exhibited similar catalytic performance as compared with the commercial zeolite X catalyst. XRD, N 2 adsorption, SEM, XPS, and H 2 -TPR were used to investigate the relationship among the structure, physicochemical properties, and catalytic activities of the catalysts. Finally, the mechanism of NH 3 -SCR reaction on Mn-Ce/zeolite X was systematically performed by using diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The characterization results showed that the amorphous structure and good dispersion between Mn and Ce on the surface of the zeolite changed the electronic properties of the active components, improved its low-temperature catalytic activity, brought it characteristics of Mn and Ce at the same time, and broaden the reaction temperature range. The NO conversion rate of Mn-Ce-FX catalyst remained above 80% at 200 ° C–300 ° C. From DRIFTS we suggest that Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism are simultaneously carried out on the catalyst surface. According to the FTIR results, the Eley-Rideal mechanism has a great influence on the reaction below 250 ° C, and the Brønsted acid sites adsorb a large amount of NH 3 , resulting in an excellent low-temperature activity. When above 250 ° C, Langmuir-Hinshelwood mechanism plays a dominant role. The nitrates on the surface gradually convert to bidentate nitrates, impeding the SCR reaction, could be one of the reasons for reducing the high-temperature activity.
{"title":"Research on Performance and Mechanism of the NH3-SCR Reaction over Fly Ash-derived Mn-Ce/Zeolite X","authors":"Weijia Ren, Qifeng Xin, Zhesheng Hua, Zhong Zheng, Lifeng Xiao, Shaojun Liu, Chenghang Zheng, Yang Yang","doi":"10.4209/aaqr.230032","DOIUrl":"https://doi.org/10.4209/aaqr.230032","url":null,"abstract":"Zeolite X was synthesized from fly ash under optimized conditions, which was supported with Mn, Ce, and Mn-Ce respectively. Fly ash-derived zeolite X catalysts exhibited similar catalytic performance as compared with the commercial zeolite X catalyst. XRD, N 2 adsorption, SEM, XPS, and H 2 -TPR were used to investigate the relationship among the structure, physicochemical properties, and catalytic activities of the catalysts. Finally, the mechanism of NH 3 -SCR reaction on Mn-Ce/zeolite X was systematically performed by using diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The characterization results showed that the amorphous structure and good dispersion between Mn and Ce on the surface of the zeolite changed the electronic properties of the active components, improved its low-temperature catalytic activity, brought it characteristics of Mn and Ce at the same time, and broaden the reaction temperature range. The NO conversion rate of Mn-Ce-FX catalyst remained above 80% at 200 ° C–300 ° C. From DRIFTS we suggest that Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism are simultaneously carried out on the catalyst surface. According to the FTIR results, the Eley-Rideal mechanism has a great influence on the reaction below 250 ° C, and the Brønsted acid sites adsorb a large amount of NH 3 , resulting in an excellent low-temperature activity. When above 250 ° C, Langmuir-Hinshelwood mechanism plays a dominant role. The nitrates on the surface gradually convert to bidentate nitrates, impeding the SCR reaction, could be one of the reasons for reducing the high-temperature activity.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70296816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Oujidi, A. Benchrif, M. Tahri, F. Zahry, M. Bounakhla, Hocein Bazairi, N. Mhammdi, M. Snoussi
Mediterranean urban areas are reportedly affected by poor air quality due to numerous emission sources, as well as topography and meteorological conditions that facilitate the accumulation of pollution. This present study makes an initial attempt to assess the effect of gaseous pollutants (NO 2 , CO, and O 3 ) and particulate matter (PM 2.5 and PM 10 ) on the air quality of Nador city, which lies on the Mediterranean coast of Morocco. Three daily, short-term sampling campaigns were conducted between 2016 and 2018 in an urban area. The concentrations of PM 2.5 and PM 10 together with elemental compositions (up to 16 elements) and black carbon content were determined. The obtained data were characterized using descriptive analysis, correlation matrices, elemental enrichment factors (EFs), and elemental ratios. On average, the particulate matter and gaseous pollutant concentrations were below the national standard limits. Two categories of PM 2.5 and PM 10 sources, as derived from the EF investigation, were defined as soil/crustal (Ti, Al, Mn, Sr, K, Na, Ba, and V) and anthropogenic (Ni, Cr, Cu, Zn, and Pb). For black carbon, biomass burning was found to be the largest contributing source (3.1–8.4 µ g m –3 ), more so than fossil fuels (0.9–1.8 µ g m –3 ). This study highlights that an air quality management plan should be established for Nador city, including the implementation of a network of monitoring stations to help with identifying and controlling the activities causing air pollution.
据报告，地中海城市地区受到空气质量差的影响，原因是排放源众多，而且地形和气象条件也助长了污染的积累。本研究初步尝试评估气态污染物(NO 2、CO和O 3)和颗粒物(PM 2.5和PM 10)对摩洛哥地中海沿岸纳多尔市空气质量的影响。2016年至2018年期间，在城市地区进行了三次每日短期抽样活动。测定了pm2.5和pm10的浓度以及元素组成(多达16种元素)和黑碳含量。利用描述性分析、相关矩阵、元素富集因子(EFs)和元素比对所得数据进行了表征。颗粒物和气态污染物的平均浓度低于国家标准限值。根据EF的调查，PM 2.5和PM 10的两类来源被定义为土壤/地壳(Ti, Al, Mn, Sr, K, Na, Ba和V)和人为(Ni, Cr, Cu, Zn和Pb)。对于黑碳，生物质燃烧被发现是最大的贡献源(3.1-8.4µg m -3)，超过化石燃料(0.9-1.8µg m -3)。本研究强调，应为纳多尔市制定空气质量管理计划，包括实施监测站网络，以帮助识别和控制造成空气污染的活动。
{"title":"Gaseous Pollutants and Particulate Matter in Ambient Air: First Field Experiment in an Urban Mediterranean Area (Nador, Morocco)","authors":"B. Oujidi, A. Benchrif, M. Tahri, F. Zahry, M. Bounakhla, Hocein Bazairi, N. Mhammdi, M. Snoussi","doi":"10.4209/aaqr.220451","DOIUrl":"https://doi.org/10.4209/aaqr.220451","url":null,"abstract":"Mediterranean urban areas are reportedly affected by poor air quality due to numerous emission sources, as well as topography and meteorological conditions that facilitate the accumulation of pollution. This present study makes an initial attempt to assess the effect of gaseous pollutants (NO 2 , CO, and O 3 ) and particulate matter (PM 2.5 and PM 10 ) on the air quality of Nador city, which lies on the Mediterranean coast of Morocco. Three daily, short-term sampling campaigns were conducted between 2016 and 2018 in an urban area. The concentrations of PM 2.5 and PM 10 together with elemental compositions (up to 16 elements) and black carbon content were determined. The obtained data were characterized using descriptive analysis, correlation matrices, elemental enrichment factors (EFs), and elemental ratios. On average, the particulate matter and gaseous pollutant concentrations were below the national standard limits. Two categories of PM 2.5 and PM 10 sources, as derived from the EF investigation, were defined as soil/crustal (Ti, Al, Mn, Sr, K, Na, Ba, and V) and anthropogenic (Ni, Cr, Cu, Zn, and Pb). For black carbon, biomass burning was found to be the largest contributing source (3.1–8.4 µ g m –3 ), more so than fossil fuels (0.9–1.8 µ g m –3 ). This study highlights that an air quality management plan should be established for Nador city, including the implementation of a network of monitoring stations to help with identifying and controlling the activities causing air pollution.","PeriodicalId":7402,"journal":{"name":"Aerosol and Air Quality Research","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70295585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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