ADSORPTION OF ORGANIC MATTER AT MINERAL/WATER INTERFACES: I. ATR-FTIR SPECTROSCOPIC AND QUANTUM CHEMICAL STUDY OF OXALATE ADSORBED AT BOEHMITE/WATER AND CORUNDUM/WATER INTERFACES
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dc.contributor.author | Yoon T.H. | |
dc.contributor.author | Johnson S.B. | |
dc.contributor.author | Musgrave C.B. | |
dc.contributor.author | Brown Jr.G.E. | |
dc.date.accessioned | 2022-03-19T11:05:22Z | |
dc.date.available | 2022-03-19T11:05:22Z | |
dc.date.issued | 2004 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=12090418 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2004, 68, 22, 4505-4518 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/36442 | |
dc.description.abstract | The types and structures of adsorption complexes formed by oxalate at boehmite (γ-AlOOH)/water and corundum (α-Al2O3)/water interfaces were determined using in situ attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy and quantum chemical simulation methods. At pH 5.1, at least four different oxalate species were found at or near the boehmite/water interface for oxalate surface coverages (Γox) ranging from 0.25 to 16.44 μmol/m². At relatively low coverages (Γox < 2.47), strongly adsorbed inner-sphere oxalate species (IR peaks at 1286, 1418, 1700, and 1720 cm⁻¹) replace weakly adsorbed carbonate species, and a small proportion of oxalate anions are adsorbed in an outer-sphere mode (IR peaks at 1314 and 1591 cm⁻¹). IR peaks indicative of inner-sphere adsorbed oxalate are also observed for oxalate at the corundum/water interface at Γox = 1.4 μmol/m². With increasing oxalate concentration (Γox > 2.47 μmol/m²), the boehmite surface binding sites for inner-sphere adsorbed oxalate become saturated, and excess oxalate ions are present dominantly as aqueous species (IR peaks at 1309 and 1571 cm⁻¹). In addition to these adsorption processes, oxalate-promoted dissolution of boehmite following inner-sphere oxalate adsorption becomes increasingly pronounced with increasing Γox and results in an aqueous Al(III)-oxalate species, as indicated by shifted IR peaks (1286 → 1297 cm⁻¹ and 1418 → 1408 cm⁻¹). At pH 2.5, no outer-sphere adsorbed oxalate or aqueous oxalate species were observed. The similarity of adsorbed oxalate spectral features at pH 2.5 and 5.1 implies that the adsorption mechanism of aqueous HOx⁻ species involves loss of protons from this species during the ligand-exchange reaction. As a consequence, adsorbed inner-sphere oxalate and aqueous Al(III)-oxalate complexes formed at pH 2.5 have coordination geometries very similar to those formed at pH 5.1. | |
dc.title | ADSORPTION OF ORGANIC MATTER AT MINERAL/WATER INTERFACES: I. ATR-FTIR SPECTROSCOPIC AND QUANTUM CHEMICAL STUDY OF OXALATE ADSORBED AT BOEHMITE/WATER AND CORUNDUM/WATER INTERFACES | |
dc.type | Статья |
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