These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.
Pubmed for Handhelds
PUBMED FOR HANDHELDS
Search MEDLINE/PubMed
Title: Photo-redox reactions of dicarboxylates and α-hydroxydicarboxylates at the surface of Fe(III)(hydr)oxides followed with in situ ATR-FTIR spectroscopy. Author: Borer P, Hug SJ. Journal: J Colloid Interface Sci; 2014 Feb 15; 416():44-53. PubMed ID: 24370400. Abstract: Colloidal mineral-phases play an important role in the adsorption, transport and transformation of organic and inorganic compounds in the atmosphere and in aqueous environments. Artificial UV-light and sunlight can induce electron transfer reactions between metal ions of the solid phases and adsorbed compounds, leading to their transformation and degradation. To investigate different possible photo-induced oxidation pathways of dicarboxylates adsorbed on iron(III)(hydr)oxide surfaces, we followed UV-A induced photoreactions of oxalate, malonate, succinate and their corresponding α-hydroxy analogues tartronate and malate with in situ ATR-FTIR spectroscopy in immersed particle layers of lepidocrocite, goethite, maghemite and hematite at pH 4. UV-A light (365 ± 5 nm) lead to fast degradation of oxalate, tartronate and malate, while malonate and succinate were photo-degraded at much slower rates. Efficient generation of OH-radicals can be excluded, as this would lead to fast and indiscriminate degradation of all tested compounds. Rapid photo-degradation of adsorbed oxalate and the α-hydroxydicarboxylates must be induced by direct ligand-to-metal charge transfer (LMCT) or by selectively oxidizing valence band holes, both processes requiring inner-sphere coordination with direct ligand-to-metal bonds to enable efficient electron-transfer. The slow photo-degradation of malonate and succinate can be explained by low-yield production of OH-radicals at the surface of the iron(III)(hydr)oxides.[Abstract] [Full Text] [Related] [New Search]