Huminstoffbildung unter katalyischer Einwirkung natürlich vorkommender Eisenverbindungen im Modellversuch

Scheffer, F.; Meyer, B.; Niederbudde, E. A.

doi:10.1002/jpln.19590870104

Cited by 26 publications

(3 citation statements)

References 23 publications

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“…This reaction is cata-Many microorganisms reduce the distance to the substrate source by adhering to non-aqueous phase liquids, lyzed by peroxidases and phenol mono-oxygenases [77] and by inorganic materials, such as oxides and oxyhydrox-solid substrates, or organic matter containing their substrate. Marshall and Cruickshank observed the partitioning ides of iron [97], allophane [66], and silica and clay [118]. Phenolic lignin derivatives, such as vanillic acid, vanillin, of bacteria into an oil phase followed by perpendicular orientation of the cells at the oil-water interface [76].…”

Section: Spatial Distribution Of Pollutants and Microbesmentioning

confidence: 99%

Mass transfer limitation of microbial growth and pollutant degradation

Harms

Bosma

1997

Journal of Industrial Microbiology and Biotechnology

215

131

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Organic pollutants in soil can be removed by biotechnological treatment. A limitation of this technology is the efficiency of biodegradation. In many cases, the bulk of the pollution can be removed but residual pollutants remain and biodegradation rates are slower than expected from laboratory trials. Low biodegradation rates are often a result of limited accessibility of the pollutants. Major reasons for the reduced bioavailability are the unequal spatial distribution of microorganisms and pollutants and the retardation of substrate diffusion by the soil matrix. Mechanical mixing and the addition of surfactants are possible approaches to improve the bioavailability of pollutants during bioremediation. The application of flow-stop-flow techniques may be of help to overcome the limitations resulting from advective-diffusive transport mechanisms during pump-and-treat remediation of contaminant plumes.

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Section: Spatial Distribution Of Pollutants and Microbesmentioning

confidence: 99%

Mass transfer limitation of microbial growth and pollutant degradation

Harms

Bosma

1997

Journal of Industrial Microbiology and Biotechnology

215

131

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“…Studies by Scheffer et al (1959), designed to model the synthesis of humic substances by iron oxides at various pHs, reported dark-colored products in solution (as measured by the optical density), as well as at the surface of the oxides. This process of "humification" was significantly stimulated by the presence of iron oxides.…”

Section: Introductionmentioning

confidence: 99%

Electron Transfer Processes Between Hydroquinone and Iron Oxides

Kung

1988

Clays and clay miner.

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Abstract-The kinetics of hydroquinone oxidation by aqueous suspensions of pure hematite and goethiteferrihydrite mixtures at pH 6.0, 7.4, and 9 was studied using an on-line analysis system. The electron transfer between hydroquinone and the Fe oxides was monitored by UV-visible and electron spin resonance spectroscopy. The adsorption of organics on the Fe oxide surface was detected by Fourier-transform infrared spectroscopy. For different Fe oxides, a higher surface area was correlated with a greater oxidizing ability and greater adsorption of organics, suggesting that the oxidation reaction was a surface process. A reversal of the initially rapid redox reaction was found in this system, suggesting a delayed release of Fe E § into solution as the reduction of the Fe oxide proceeded. Redox potential calculations confirmed the thermodynamic favorability of the reaction reversal. A distribution of the reduced state over neighboring Fe atoms on the oxide surface probably was responsible for the initial suppression of Fe 2+ release into the aqueous phase. Based upon these observations and detection of the semiquinone radical as an intermediate of hydroquinone oxidation, an inner-sphere one-electron transfer mechanism for the oxidation of hydroquinone at the oxide surface is proposed.

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“…Bloomfield (2), on the one hand, indicated the importance of polyphenols as a mobilizing agent, and on the other. Scheffer et al (8) and the authors (6) immobilization and catalytic transfonnation (oxidative polymerization) in B horizon would be a likely explanation for the fonnation of humus ulluvial horizons (Bh) in podzolic soil profiles. As Bh humus studied by Martin and Reeve (7) and Schnitzer and Wright (9, 13) seems to have characteristics similar to oxidatively transformed polyphenols, this hypothesis would be worth being tested.…”

Section: Discussionmentioning

confidence: 97%