Nahin Ferdousi-Rokib, Kotiba A. Malek, Ian Mitchell, Laura M. Fierce and Akua A. Asa-Awuku*,
{"title":"气溶胶吸湿性和气溶胶混合物液滴生长的表面活性覆盖","authors":"Nahin Ferdousi-Rokib, Kotiba A. Malek, Ian Mitchell, Laura M. Fierce and Akua A. Asa-Awuku*, ","doi":"10.1021/acsestair.4c00303","DOIUrl":null,"url":null,"abstract":"<p >The partitioning between inorganic salts and organic compounds within individual particles is a key factor that influences the uptake of water by particles. In this study, we investigated the aerosol hygroscopicity of ammonium sulfate (AS) and 2-methylglutaric acid (2-MGA) mixtures. 2-MGA is a moderately surface-active compound. Dilute surface tension measurements of 2-MGA/AS mixtures were taken by using a pendant drop goniometer. Hygroscopicity at subsaturated conditions was determined using a hygroscopicity tandem differential mobility analyzer (H-TDMA) and relative humidity was kept constant at 89 ± 0.9% RH. The droplet activation was also measured at supersaturated conditions using a cloud condensation nuclei counter (CCNC) from 0.4 to 1% supersaturation (SS). The single-hygroscopicity parameter κ was derived from measurements. Mixtures predominantly composed of AS, up to a 60 wt% 2-MGA, exhibit κ-values close to pure AS. However, κ decreases significantly as the organic fraction increases (>60 wt% 2-MGA). Previous predictions of κ-hygroscopicity assume full dissolution of both the organic and inorganic compounds. However, organic partitioning can influence the κ-hygroscopicity. A coverage-based parametrization, ϕ, assumes the probability of surface-active organics at the droplet surface. By estimation of the bulk and surface organic contribution, overall κ-hygroscopicity can be calculated. The model is computationally efficient, and the results indicate that organic solute depletion should be considered for fully soluble surface-active organics. Hygroscopicity predictions that account for the role of organic surface-active partitioning agree best with experimental results (<i>R</i><sup><i>2</i></sup> > 0.95). Therefore, this study helps to enhance our understanding of cloud-forming properties of complex chemical mixtures containing surface-active organic and inorganic compounds.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 8","pages":"1454–1467"},"PeriodicalIF":0.0000,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Aerosol Hygroscopicity and Surface-Active Coverage for the Droplet Growth of Aerosol Mixtures\",\"authors\":\"Nahin Ferdousi-Rokib, Kotiba A. Malek, Ian Mitchell, Laura M. Fierce and Akua A. Asa-Awuku*, \",\"doi\":\"10.1021/acsestair.4c00303\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >The partitioning between inorganic salts and organic compounds within individual particles is a key factor that influences the uptake of water by particles. In this study, we investigated the aerosol hygroscopicity of ammonium sulfate (AS) and 2-methylglutaric acid (2-MGA) mixtures. 2-MGA is a moderately surface-active compound. Dilute surface tension measurements of 2-MGA/AS mixtures were taken by using a pendant drop goniometer. Hygroscopicity at subsaturated conditions was determined using a hygroscopicity tandem differential mobility analyzer (H-TDMA) and relative humidity was kept constant at 89 ± 0.9% RH. The droplet activation was also measured at supersaturated conditions using a cloud condensation nuclei counter (CCNC) from 0.4 to 1% supersaturation (SS). The single-hygroscopicity parameter κ was derived from measurements. Mixtures predominantly composed of AS, up to a 60 wt% 2-MGA, exhibit κ-values close to pure AS. However, κ decreases significantly as the organic fraction increases (>60 wt% 2-MGA). Previous predictions of κ-hygroscopicity assume full dissolution of both the organic and inorganic compounds. However, organic partitioning can influence the κ-hygroscopicity. A coverage-based parametrization, ϕ, assumes the probability of surface-active organics at the droplet surface. By estimation of the bulk and surface organic contribution, overall κ-hygroscopicity can be calculated. The model is computationally efficient, and the results indicate that organic solute depletion should be considered for fully soluble surface-active organics. Hygroscopicity predictions that account for the role of organic surface-active partitioning agree best with experimental results (<i>R</i><sup><i>2</i></sup> > 0.95). Therefore, this study helps to enhance our understanding of cloud-forming properties of complex chemical mixtures containing surface-active organic and inorganic compounds.</p>\",\"PeriodicalId\":100014,\"journal\":{\"name\":\"ACS ES&T Air\",\"volume\":\"2 8\",\"pages\":\"1454–1467\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2025-07-07\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"ACS ES&T Air\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/acsestair.4c00303\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS ES&T Air","FirstCategoryId":"1085","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acsestair.4c00303","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Aerosol Hygroscopicity and Surface-Active Coverage for the Droplet Growth of Aerosol Mixtures
The partitioning between inorganic salts and organic compounds within individual particles is a key factor that influences the uptake of water by particles. In this study, we investigated the aerosol hygroscopicity of ammonium sulfate (AS) and 2-methylglutaric acid (2-MGA) mixtures. 2-MGA is a moderately surface-active compound. Dilute surface tension measurements of 2-MGA/AS mixtures were taken by using a pendant drop goniometer. Hygroscopicity at subsaturated conditions was determined using a hygroscopicity tandem differential mobility analyzer (H-TDMA) and relative humidity was kept constant at 89 ± 0.9% RH. The droplet activation was also measured at supersaturated conditions using a cloud condensation nuclei counter (CCNC) from 0.4 to 1% supersaturation (SS). The single-hygroscopicity parameter κ was derived from measurements. Mixtures predominantly composed of AS, up to a 60 wt% 2-MGA, exhibit κ-values close to pure AS. However, κ decreases significantly as the organic fraction increases (>60 wt% 2-MGA). Previous predictions of κ-hygroscopicity assume full dissolution of both the organic and inorganic compounds. However, organic partitioning can influence the κ-hygroscopicity. A coverage-based parametrization, ϕ, assumes the probability of surface-active organics at the droplet surface. By estimation of the bulk and surface organic contribution, overall κ-hygroscopicity can be calculated. The model is computationally efficient, and the results indicate that organic solute depletion should be considered for fully soluble surface-active organics. Hygroscopicity predictions that account for the role of organic surface-active partitioning agree best with experimental results (R2 > 0.95). Therefore, this study helps to enhance our understanding of cloud-forming properties of complex chemical mixtures containing surface-active organic and inorganic compounds.