مورد إلكتروني
Water film-driven Mn (oxy)(hydr)oxide nanocoating growth on rhodochrosite
| العنوان: | Water film-driven Mn (oxy)(hydr)oxide nanocoating growth on rhodochrosite |
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| بيانات النشر: | Umeå universitet, Kemiska institutionen Pacific Northwest National Laboratory, WA, Richland, United States 2022 |
| تفاصيل مُضافة: | Luong, N. Tan Ilton, Eugene S. Shchukarev, Andrey Boily, Jean-Francois |
| نوع الوثيقة: | Electronic Resource |
| مستخلص: | Minerals exposed to moist air stabilize thin water films that drive a score of chemical reactions of great importance to water-unsaturated terrestrial environments. In this study, we identified Mn (oxy)(hydr)oxide nanocoatings formed by the dissolution, oxidation and precipitation of Mn in oxygenated water films grown on rhodochrosite (MnCO3) microparticles. Nanocoatings that could be identified by vibrational spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and (scanning and transmission) electron microscopy formed in water films containing the equivalent of at least 7 monolayers (∼84 H2O/nm2). These films were formed by exposing microparticles to moist air with at least 50% relative humidity (RH). Films of neutral pH reacted up to 14% of the MnII located in the topmost ∼5 nm region of the microparticles in atmospheres of up to 90% RH for 7 d. These reactions produced MnOOH, birnessite (MnO2) and hausmannite (Mn3O4) nanoparticles of low crystallinity, while exposure to atmospheric air for 1 yr. converted only 2% of MnII in this region to MnOOH. In contrast, reactions in alkaline water films converted up to ∼75% of the MnII but only after 16 d of reaction. These films produced MnOOH and MnO2 of low crystallinity, as well as crystalline hausmannite. Kinetic modeling of the time-resolved growth of the Mn[sbnd]O stretching vibrational bands of these nanocoatings revealed two concurrent reaction processes. A 1rst-order process was assigned to nucleation events terminating only after a few hours, and a 0-order process was assigned to the sustained growth of nanocoatings from these nuclei over longer reaction time. By identifying nanocoatings formed by water film-driven reactions on rhodochrosite, our study adds new insight into mineralogical transformations relevant to anoxic–oxic boundaries in water-unsaturated environments. |
| مصطلحات الفهرس: | Oxidation, Precipitation, Rhodochrosite, Water films, Inorganic Chemistry, Oorganisk kemi, Article in journal, info:eu-repo/semantics/article, text |
| DOI: | 10.1016.j.gca.2022.05.019 |
| URL: | Geochimica et Cosmochimica Acta, 0016-7037, 2022, 329, s. 87-105 |
| الإتاحة: | Open access content. Open access content info:eu-repo/semantics/openAccess |
| ملاحظة: | application/pdf English |
| أرقام أخرى: | UPE oai:DiVA.org:umu-203210 0000-0002-0118-8207 0000-0002-4766-2672 0000-0003-4954-6461 doi:10.1016/j.gca.2022.05.019 ISI:000818523300006 Scopus 2-s2.0-85132406337 1372228083 |
| المصدر المساهم: | UPPSALA UNIV LIBR From OAIster®, provided by the OCLC Cooperative. |
| رقم الأكسشن: | edsoai.on1372228083 |
| قاعدة البيانات: | OAIster |
| DOI: | 10.1016.j.gca.2022.05.019 |
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