ACS ES&T Air最新文献

{"title":"Unveiling the Limits of Existing Correction Factors for a Low-Cost PM2.5 Sensor in Cold Environments and Development of a Tailored Solution","authors":"Jenno F. Leenose,&nbsp;Alana Vilagi,&nbsp;Dominique Pride,&nbsp;Raghu Betha* and Srijan Aggarwal*,&nbsp;","doi":"10.1021/acsestair.5c00018","DOIUrl":"https://doi.org/10.1021/acsestair.5c00018","url":null,"abstract":"<p >PM_2.5 poses significant health risks and requires accurate monitoring. While the EPA’s high-cost Federal Reference Methods and Federal Equivalent Methods provide reliable data, they are often sparsely distributed, limiting community-scale assessments. Low-cost sensors like PurpleAir (PA) offer a promising alternative but require careful location-specific calibration and correction for environmental influences. Although several correction factors have been developed for use across regions and nationwide, these models often exhibit bias due to the predominance of data from temperate and warmer climates. This study was conducted to evaluate the performance of PA sensors in measuring PM_2.5 in extremely cold environments, specifically North Pole, Alaska. Data from PA sensors and a Beta Attenuation Monitoring (BAM) reference sensor were used to develop correction models. The study found that temperature and relative humidity significantly influenced PA sensor accuracy in the region. By comparing various regression models, including Ordinary Least Squares, Lasso, Ridge, and Elastic Net, an optimal model was identified that substantially reduced errors and aligned PA sensor data with BAM measurements. This research highlights the importance of localized calibration models to enhance the reliability of low-cost air quality sensors in diverse environmental conditions, particularly in cold regions.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1191–1201"},"PeriodicalIF":0.0,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical Aging of Semivolatile Secondary Organic Aerosol Sesquiterpene Products","authors":"Christina N. Vasilakopoulou,&nbsp;Agata Blaziak,&nbsp;Damianos Pavlidis,&nbsp;Angeliki Matrali,&nbsp;Kalliopi Florou,&nbsp;Petro Uruci and Spyros N. Pandis*,&nbsp;","doi":"10.1021/acsestair.5c00011","DOIUrl":"10.1021/acsestair.5c00011","url":null,"abstract":"<p >The oxidation of biogenic volatile organic compounds (bVOCs) is a significant source of secondary organic aerosols (SOA). This study investigates later-generation SOA formation from the reactions of three first-generation sesquiterpene ozonolysis products (β-nocaryophyllinic acid, 2-(2-carboxyethyl)-3,3-dimethylcyclobutane-carboxylic acid, and 2-(2-methyl-6-oxoheptan-3-yl)-3,6-dioxoheptanal) with the OH radical. These compounds were synthesized specifically for this study. Our results demonstrate that sesquiterpene-derived SOA can become progressively more oxidized as it reacts with OH, with an average oxygen-to-carbon (O:C) ratio of approximately 0.6, in contrast with previous studies, suggesting considerably lower ratios. As the first-generation products continue to react, the corresponding SOA aerosol mass spectrometer (AMS) mass spectrum changes by 20–25° compared to that of the fresh SOA. This suggests that quantifying the sesquiterpene SOA under ambient conditions based on its ozonolysis products may be problematic. To account for these observations, we propose and test a physicochemical model describing the processes that convert first-generation sesquiterpene SOA into highly oxidized compounds. Our analysis suggests that approximately two-thirds of carbon in the ozonolysis SOA follows functionalization pathways. The parametrizations developed in this work can be utilized in future modeling efforts to reassess the contribution of sesquiterpenes to SOA formation.</p><p >The later-generation SOA formation during the reaction with OH of sesquiterpenes ozonolysis products is explored, and a physicochemical mechanism is proposed.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1180–1190"},"PeriodicalIF":0.0,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12261276/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144651773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methane Sensor Characterization Using Colocated Ambient Comparisons and Simulated Emission Challenges","authors":"Wyatt M. Champion*,&nbsp;Megan K. MacDonald,&nbsp;Brittany Thomas,&nbsp;Sarat Chandra Bantupalli and Eben D. Thoma,&nbsp;","doi":"10.1021/acsestair.5c00110","DOIUrl":"https://doi.org/10.1021/acsestair.5c00110","url":null,"abstract":"<p >Methane sensing technologies have wide applications, including leak detection and repair in the energy sector and emissions monitoring from landfills and agriculture. Lower-cost units, as opposed to reference-grade instrumentation, may be deployed in many forms (e.g., sensor networks, unmanned aerial vehicles, and mobile monitoring) and allow vastly improved spatial and temporal data resolution owing to their scalability. Ultimately, early detection of unexpected emissions enabled by lower-cost sensing technologies provides industry with rapid operational feedback, allowing for emission reductions and improved process control. The expanded use of such technologies allows for consolidation and resolution of “bottom-up” emission inventories with results using emerging “top-down” techniques (e.g., satellite measurements), thereby improving emissions management on many scales. Here, we introduce a novel testing method to assess four leading commercial methane monitoring technologies that employ three distinct working principles: metal oxide (MOx) conductometry, tunable diode laser (TDL) spectrometry, and photoacoustic spectrometry (PAS). We assess both nominal baseline performance and sensor response using ambient measurements and controlled release experiments, respectively. We observe the PAS technology to provide the lowest baseline signal noise (and therefore the lowest detection limit), followed by TDL and MOx. We also observe PAS to have the highest agreement with reference instrumentation during simulated emission plume events (with TDL and MOx technologies generally trailing in accuracy). Outcomes of this work include guidance for researchers and practitioners seeking to better understand the best available commercial methane sensor technology. Analysis approaches employed here may also be applied to many other low-cost gas sensing technologies.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1359–1368"},"PeriodicalIF":0.0,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoenhanced Uptake of SO2 and Organosulfate Formation at the Air–Aqueous Interface","authors":"Qian Zhang,&nbsp;Yiqun Wang and Christian George*,&nbsp;","doi":"10.1021/acsestair.5c00028","DOIUrl":"https://doi.org/10.1021/acsestair.5c00028","url":null,"abstract":"<p >Organosulfate, a common constituent of atmospheric aerosols, contributes significantly to particle mass and the secondary organic aerosol formation. While recent studies have investigated the photosensitized oxidation of SO₂─typically focusing on inorganic sulfate formation─the mechanisms underlying the multiphase formation of organosulfate remain largely unexplored. This study identifies a potential pathway for organosulfate formation via a radical–radical mechanism under highly acidic conditions, involving an interaction between organic radicals and sulfate radicals generated through photosensitization chemistry. Using photosensitizing films composed of vanillin, 4-benzoylbenzoic acid, and humic acid in a vertical wetted-wall flow tube reactor, SO₂ uptake was examined under both irradiated and dark conditions. Product analysis was conducted using ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry. Results revealed substantial SO₂ consumption under irradiation, with uptake rates significantly enhanced compared to dark conditions, likely due to oxidation by excited triplet states. The second-order rate constants for SO₂ reacting on the irradiated films follow the order: 4-benzoylbenzoic acid (6.9 × 10⁷ M^–1 s^–1) &gt; vanillin (4.56 × 10⁷ M^–1 s^–1), where the value for 4-BBA is the direct experimentally determined in Wang’s study (refer 21). Our findings suggest photosensitized oxidation may serve as an unrecognized pathway for gas-aqueous organosulfate formation, offering insights on previously unrecognized and overlooked OS sources, particularly those stemming from biomass burning.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1226–1236"},"PeriodicalIF":0.0,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of Brown Carbon from Aqueous-Phase Limonene SOA Reactions with Reduced Nitrogen Species: Effects of Gas-Phase Precursors and Drying Conditions","authors":"Nethmi Y. Kasthuriarachchi,&nbsp;Laura-Helena Rivellini and Alex K. Y. Lee*,&nbsp;","doi":"10.1021/acsestair.5c00054","DOIUrl":"https://doi.org/10.1021/acsestair.5c00054","url":null,"abstract":"<p >Aqueous-phase processing of secondary organic aerosols (SOAs) from limonene oxidation can generate brown carbon (BrC) through reactions with reduced nitrogen species. This study provides laboratory evidence that dark ozonolysis of limonene, in the presence of biogenic (α-pinene) or anthropogenic (toluene) precursors, generates SOAs more effectively in BrC formation when subsequently dried with (NH₄)₂SO₄/glycine in bulk solutions, and toluene had a stronger effect than α-pinene in promoting oligomeric BrC formation. BrC absorption was significantly enhanced in limonene-SOA and the (NH₄)₂SO₄/glycine mixed droplet upon evaporation at ∼75% RH but was suppressed at lower RH, likely due to reduced aerosol liquid water and precursor evaporation. RH-dependent trends were also observed in SOA generated by limonene and toluene mixtures (lim/tol-SOA), with the strongest oligomeric BrC absorption at ∼85% RH for both (NH₄)₂SO₄ and glycine systems. While bulk-dried experiments showed 1–2 orders of magnitude differences in BrC absorption between limonene-SOA and lim/tol-SOA, evaporated droplets exhibited no significant differences. This study underscores the importance of studying the effects of SOA precursors, atmospherically relevant drying conditions, and volatility of BrC precursors on the light absorption properties of complex SOAs via aqueous-phase processing.</p><p >This study provides insights into how atmospheric processing of biogenic and anthropogenic emissions influences brown carbon formation in aqueous droplets, and the dynamic behavior of brown carbon formation upon evaporation at different humidity conditions.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1271–1279"},"PeriodicalIF":0.0,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acsestair.5c00054","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive Evaluation of Simulation Performance of Nonmethane Hydrocarbons (NMHCs) and Oxygenated VOCs in China Using a Three-Dimensional Numerical Model","authors":"Yibo Zhang,&nbsp;Dejia Yin,&nbsp;Shuxiao Wang,&nbsp;Shengyue Li,&nbsp;Bin Yuan,&nbsp;Min Shao,&nbsp;Hong Li,&nbsp;Qinwen Tan,&nbsp;Qing Li,&nbsp;Yanlin Zhang,&nbsp;Guiqian Tang,&nbsp;Chun Zhao,&nbsp;Qiuyan Du,&nbsp;Yun Zhu,&nbsp;Jie Li,&nbsp;Fenfen Zhang and Bin Zhao*,&nbsp;","doi":"10.1021/acsestair.5c00066","DOIUrl":"https://doi.org/10.1021/acsestair.5c00066","url":null,"abstract":"<p >Volatile organic compounds (VOCs), particularly oxygenated VOCs (OVOCs), critically influence ozone (O₃₎ formation through free radical production. However, comprehensive evaluations of three-dimensional models in simulating both nonmethane hydrocarbons (NMHCs) and OVOCs remain scarce, hindering O₃ control strategies. This study systematically evaluates the Community Multiscale Air Quality model (CMAQv5.3.3) using hourly observations from 12 monitoring sites across China from 2017 to 2021. Results reveal that the model underestimates NMHCs by 22.0% and OVOCs by 43.7%, on average. Within the 14 abundant OVOC components, formaldehyde (HCHO) and ketones (PRD2) show overpredictions, while other OVOCs are underpredicted (4.7–94.2%), with simulated OVOC contributions to total VOCs (8.8–36.7%) being substantially lower than observations (16.6–60.8%). The model exhibits persistent underestimation in daytime concentrations across seasons and shows stronger declines in daytime concentrations from nighttime peaks compared to observations, which suggests overestimated atmospheric physical diffusion or vertical mixing processes. Residual error analysis after subtracting the simulation bias of NMHCs (primarily attributed to biases in emissions and atmospheric physical processes) highlights inadequate secondary chemical formation as a major bias source for OVOCs. Sensitivity experiments demonstrate that conventional adjustments to boundary layer and surface parametrization schemes, minimum turbulent diffusivity (Kzmin), or primary emissions failed to resolve daytime OVOCs underestimation. On the contrary, adjusting eddy diffusivity values during the day, the local vertical gradient in an unstable atmospheric state, and the yield coefficient for OVOCs chemical formation effectively enhance the simulated daytime concentrations of OVOCs and reduce the model bias. This study highlights that better descriptions of the atmospheric diffusion or vertical mixing processes during the daytime and the secondary chemical formations of OVOCs should be prioritized to improve the performance of NMHCs and OVOCs modeling.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1292–1307"},"PeriodicalIF":0.0,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anthropogenic Dominance and Secondary Processes Drive Aerosol Iron Solubility in Asian Continental Outflow: Insights from Spring Qingdao, China","authors":"Wenshuai Li,&nbsp;Yuxuan Qi,&nbsp;Guanru Wu,&nbsp;Youtian Zhang,&nbsp;Rongrong Han,&nbsp;Yingchen Liu,&nbsp;Wenjun Qu,&nbsp;Yaoyu Song,&nbsp;Xinshuo Wang,&nbsp;Tianshu Chen,&nbsp;Lifang Sheng,&nbsp;Jinhui Shi,&nbsp;Daizhou Zhang and Yang Zhou*,&nbsp;","doi":"10.1021/acsestair.5c00049","DOIUrl":"https://doi.org/10.1021/acsestair.5c00049","url":null,"abstract":"<p >Soluble aerosol iron (Fe_S) plays a critical role in marine primary productivity, yet the relative contributions of primary emissions versus secondary atmospheric processes to its abundance remain poorly quantified. Qingdao is a coastal city in eastern China, located in the Asian continental outflow, where iron constitutes one of the major mineral species in fine particles (PM_2.5). Using positive matrix factorization (PMF) analysis of PM_2.5 composition data (139 samples collected during the spring of 2017 and 2018) from Qingdao, we quantified the sources of total iron (Fe_T) and its water-soluble fraction (i.e., Fe_S) and the iron solubility (%Fe_S = Fe_S/Fe_T×100%) enhancement mechanisms. Our results revealed that while mineral dust contributed 71.1% of Fe_T, anthropogenic sources dominated Fe_S, accounting for 63.6% of Fe_S. During dust events, aged dust particles contributed about half of the Fe_S, with %Fe_S enhanced by up to 2.2-fold through atmospheric aging processes. In non-dust periods, anthropogenic sources accounted for 84.8% of Fe_S, with the %Fe_S mainly modulated by ship emissions, secondary aerosols, and aging of industrial particles. Notably, ship emissions exhibited exceptionally high %Fe_S, while secondary processes involving organic ligands and acid-processed industrial aerosols significantly enhanced %Fe_S. These findings quantitatively demonstrate the significance of anthropogenic air pollutants and secondary processes in Fe_S occurrence in Asian continental outflow, with important implications for understanding iron biogeochemical cycling in downwind marine ecosystems.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 9","pages":"1840–1848"},"PeriodicalIF":0.0,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145036398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of New Particle Formation Events Using a You Only Look Once (YOLO) Deep Learning Algorithm","authors":"Rajat Bhandari,&nbsp;Chandan Sarangi*,&nbsp;Mathew Sebastian,&nbsp;Rakesh K. Hooda,&nbsp;Antti-Pekka Hyvärinen,&nbsp;Eija Asmi,&nbsp;Ville Vakkari,&nbsp;Govindan Pandithurai,&nbsp;Sachchidanand Singh,&nbsp;Vijay K. Soni,&nbsp;Tuomo Nieminen,&nbsp;Pieter G. van Zyl,&nbsp;Kerneels Jaars,&nbsp;Lauri K. Laakso,&nbsp;David C. S. Beddows,&nbsp;Roy M. Harrison,&nbsp;Johan Paul Beukes,&nbsp;Nikos Kalivitis,&nbsp;Nikolaos Mihalopoulos,&nbsp;Imre Salma,&nbsp;Máté Vörösmarty,&nbsp;Li-Hao Young,&nbsp;Zachary Watson,&nbsp;Shan-Hu Lee,&nbsp;Michael Pikridas,&nbsp;Jean Sciare,&nbsp;Tuija Jokinen and Vijay P. Kanawade*,&nbsp;","doi":"10.1021/acsestair.5c00021","DOIUrl":"https://doi.org/10.1021/acsestair.5c00021","url":null,"abstract":"<p >Atmospheric new particle formation (NPF) events, which involve the formation and growth of molecular clusters, affect air quality, weather, climate, and human health. Traditional NPF event classification schemes in the literature, primarily through visual inspection of particle number size distributions, are subjective, time-consuming, and laborious. Here, we introduced a fast object detection deep learning algorithm, You Only Look Once (YOLO), for the first time to detect NPF events. We used more than one year of asynchronous particle number size distribution data from 20 diverse geographical locations globally. The YOLO algorithm was first trained and validated using a small subset of manually annotated 252 NPF events and 195 non-events (approximately 25 images from each measurement site). The trained YOLO algorithm was then evaluated to detect NPF events against the remaining 6462 observation days across all measurement sites. The performance metrics of the trained YOLO algorithm revealed high precision and accuracy in detecting NPF events. The model accuracy for each measurement site was calculated by taking the ratio of the total number of NPF events detected by the trained YOLO algorithm at a confidence score (CoS) &gt; 0.1 to the total number of visually identified NPF events. Considering all measurement sites, the trained YOLO algorithm’s accuracy (in fraction) for detecting NPF events ranged from 0.74 to 0.97 at a CoS &gt; 0.1, although the accuracy decreased with increasing threshold CoS. This work underscores the efficacy and robustness of the YOLO algorithm and demonstrates its applicability in accurately detecting NPF events in diverse environmental conditions worldwide.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1202–1213"},"PeriodicalIF":0.0,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variations in the Mass Absorption Efficiency of Primary Carbonaceous Aerosols from Residential Solid Fuel Combustion","authors":"Lu Zhang,&nbsp;Yaojie Li,&nbsp;Tianyao Huang,&nbsp;Zhihan Luo,&nbsp;Jin Li,&nbsp;Bingjun Han,&nbsp;Wei Du,&nbsp;Xinlei Liu,&nbsp;Qirui Zhong,&nbsp;Guofeng Shen* and Shu Tao,&nbsp;","doi":"10.1021/acsestair.5c00022","DOIUrl":"https://doi.org/10.1021/acsestair.5c00022","url":null,"abstract":"<p >High uncertainty in aerosol radiative forcing assessment is closely associated with limited knowledge of the optical properties of carbonaceous aerosols in real environments. Residential fuel combustion is a major contributor to light-absorbing brown carbon (BrC) and black carbon (BC), yet their mass absorption efficiency (MAE) and association with complex chemical components remain poorly understood. This study investigated the MAE of BrC at λ = 370 nm (MAE_BrC) and BC at λ = 880 nm (MAE_BC), focusing on their variabilities attributed to organic chemical components through 131 burning tests involving various fuel-stove combinations. The MAE_BrC, with an average of 4.8 ± 2.2 m²/g and a range of 0.35 to 10 m²/g, was comparable to previously reported values from field-based experiments; however, MAE_BC (average: 8.7 ± 3.7 m²/g, range: 2.9–28 m²/g) was obviously lower than those field-based observations. This discrepancy was attributed to the greater dependence of MAE_BC on combustion efficiency and highlighted the need for appropriate methodologies for measuring MAE values. MAE_BC increased with the rise in organic carbon-to-element carbon ratios due to the lensing effect, which was a significant factor determining the MAE_BC and explaining 36–77% of its variations. While MAE_BrC mainly depended on the different BrC chromophores emitted during combustion with protein-like substances and humic-like substances being the predominant components of BrC derived from biomass and coal combustion, contributing 31% and 46% to the light absorption of extractable BrC from biomass and coal, respectively.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1214–1225"},"PeriodicalIF":0.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fenton-like Reactions in Acidic Environments: New Mechanistic Insights and Implications to Atmospheric Particle-Phase Chemistry","authors":"Daniele Scheres Firak,&nbsp;Thomas Schaefer,&nbsp;Paula Senff,&nbsp;Peng Cheng,&nbsp;Mohamed Sarakha,&nbsp;Marcello Brigante,&nbsp;Gilles Mailhot* and Hartmut Herrmann*,&nbsp;","doi":"10.1021/acsestair.5c00077","DOIUrl":"https://doi.org/10.1021/acsestair.5c00077","url":null,"abstract":"<p >Fenton and Fenton-like processes are important oxidation cycles in the atmospheric aqueous particle phase, yet their mechanisms in the presence of iron complexes remain incompletely understood. This study investigated Fenton-like reactions in the presence of oxalate from pH 2 to 5. The rate constant for the reaction of FeC₂O₄ with H₂O₂ (Fenton-like) was derived as (3.2 ± 0.3) × 10³ M^–1 s^–1. Thermochemical analysis indicated a significant increase in activation entropy (Δ<i>S</i>^‡ = −6.0 ± 0.8 for Fenton-like versus −87 ± 9 J K^–1 mol^–1 for the Fenton in the absence of oxalate). We propose the formation of a monodentate [Fe(HC₂O₄)]⁺ complex with estimated log <i>K</i> = 1.3 ± 0.2 to account for the behavior of measured second-order rate constants at pH ≤ 3. The rate constant for the reaction between [Fe(HC₂O₄)]⁺ and H₂O₂ was estimated at (2.7 ± 0.8) × 10³ M^–1 s^–1. The Fe(II) regeneration observed in the presence of phenolic compounds was found to be relevant only at lower initial oxalate concentrations, when oxalate complexes represented less than 1% of the total Fe(II). These findings demonstrate how oxalate modifies the Fenton-like mechanism, amplifying its role in the aqueous particle-phase chemistry.</p><p >Oxalate enhances Fenton-like reactions in acidic environments, forming different Fe(II)-oxalate complexes with higher reactivity, crucial for understanding aqueous particle-phase chemistry in atmospheric aerosol particles.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 7","pages":"1315–1325"},"PeriodicalIF":0.0,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acsestair.5c00077","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144808439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}