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Perfluorooctanesulfonate (PFOS) is a toxic, bioaccumulative, and highly persistent anthropogenic chemical. Hydrated electrons (e aq –) are potent nucleophiles that can effectively decompose PFOS. In previous studies, e aq – are mainly produced by photoionization of aqueous anions or aromatic compounds. In this study, we proposed a new photolytic strategy to generate e aq – and in turn decompose PFOS, which utilizes nitrilotriacetic acid (NTA) as a photosensitizer to induce water photodissociation and photoionization, and subsequently as a scavenger of hydroxyl radical (•OH) to minimize the geminate recombination between •OH and e aq –. The net effect is to increase the amount of e aq – available for PFOS degradation. The UV/NTA process achieved a high PFOS degradation ratio of 85.4% and a defluorination ratio of 46.8% within 10 h. A pseudo-first-order rate constant (k) of 0.27 h–1 was obtained. The laser flash photolysis study indicates that e aq – is the dominant reactive species responsible for PFOS decomposition. The generation of e aq – is greatly enhanced and its half-life is significantly prolonged in the presence of NTA. The electron spin resonance (ESR) measurement verified the photodissociation of water by detecting •OH. The model compound study indicates that the acetate and amine groups are the primary reactive sites.

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In this study, iron solubility from six combustion source particles was investigated in acidic media. For comparison, a Chinese loess (CL) dust was also included. The solubility experiments confirmed that iron solubility was highly variable and dependent on particle sources. Under dark and light conditions, the combustion source particles dissolved faster and to a greater extent relative to CL. Oil fly ash (FA) yielded the highest soluble iron as compared to the other samples. Total iron solubility fractions measured in the dark after 12 h ranged between 2.9 and 74.1% of the initial iron content for the combustion-derived particles (Oil FA > biomass burning particles (BP) > coal FA). Ferrous iron represented the dominant soluble form of Fe in the suspensions of straw BP and corn BP, while total dissolved Fe presented mainly as ferric iron in the cases of oil FA, coal FA, and CL. Mössbauer measurements and TEM analysis revealed that Fe in oil FA was commonly presented as nanosized Fe(3)O(4) aggregates and Fe/S-rich particles. Highly labile source of Fe in corn BP could be originated from amorphous Fe form mixed internally with K-rich particles. However, Fe in coal FA was dominated by the more insoluble forms of both Fe-bearing aluminosilicate glass and Fe oxides. The data presented herein showed that iron speciation varies by source and is an important factor controlling iron solubility from these anthropogenic emissions in acidic solutions, suggesting that the variability of iron solubility from combustion-derived particles is related to the inherent character and origin of the aerosols themselves. Such information can be useful in improving our understanding on iron solubility from combustion aerosols when they undergo acidic processing during atmospheric transport.

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