Reaction of Hydroquinone with Hematite I. Study of Adsorption by Electrochemical-Scanning Tunneling Microscopy and X-ray Photoelectron Spectroscopy
The reaction of hematite with quinones and the quinone moieties of larger molecules may be an important factor in limiting the rate ofreductive dissolution, especially by iron-reducing bacteria. Here, the electrochemical and physical properties of hydroquinone adsorbed on hematite surfaces at pH 2.5–3 were investigated with cyclic voltammetry (CV), electrochemical-scanning tunneling microscopy (EC-STM), and X-ray photoelectron spectroscopy (XPS). An oxidation peak for hydroquinone was observed in the CV experiments, as well as (photo)reduction of iron and decomposition of the solvent. The EC-STM results indicate that hydroquinone sometimes forms an ordered monolayer with ~1.1 H₂/nm², but can be fairly disordered (especially when viewed at larger scales). XPS results indicate that hydroquinone and benzoquinone are retained at the interface in increasing amounts as the reaction proceeds, but reduced iron is not observed. These results suggest that quinones do not adsorb by an inner-sphere complex where adsorbate–surface interactions determine the adsorbate surface structure, but rather in an outer-sphere complex where interactions among the adsorbate molecules dominate.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 15007956
- Report Number(s):
- PNNL-SA-41804; 2554; KP1704020; TRN: US200424%%38
- Journal Information:
- Journal of Colloid and Interface Science, Vol. 274, Issue 2; ISSN 0021-9797
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
BACTERIA
BENZOQUINONES
DISSOLUTION
HEMATITE
OXIDATION
PHYSICAL PROPERTIES
X-RAY PHOTOELECTRON SPECTROSCOPY
SCANNING TUNNELING MICROSCOPY
Hydroquinone
Hematite
Reductive dissolution
Biological electron transfer
Environmental Molecular Sciences Laboratory