scholarly journals Nanosized Iron Oxide Colloids Strongly Enhance Microbial Iron Reduction

2009 ◽  
Vol 76 (1) ◽  
pp. 184-189 ◽  
Author(s):  
Julian Bosch ◽  
Katja Heister ◽  
Thilo Hofmann ◽  
Rainer U. Meckenstock
Keyword(s):  
Iron Oxide ◽  
Iron Oxides ◽  
Iron Reduction ◽  
Colloidal Suspension ◽  
Microbial Reduction ◽  
Geobacter Sulfurreducens ◽  
Hydrodynamic Diameter ◽  
Colloidal Iron ◽  
Surface Areas ◽  
Microbial Iron Reduction

ABSTRACT Microbial iron reduction is considered to be a significant subsurface process. The rate-limiting bioavailability of the insoluble iron oxyhydroxides, however, is a topic for debate. Surface area and mineral structure are recognized as crucial parameters for microbial reduction rates of bulk, macroaggregate iron minerals. However, a significant fraction of iron oxide minerals in the subsurface is supposed to be present as nanosized colloids. We therefore studied the role of colloidal iron oxides in microbial iron reduction. In batch growth experiments with Geobacter sulfurreducens, colloids of ferrihydrite (hydrodynamic diameter, 336 nm), hematite (123 nm), goethite (157 nm), and akaganeite (64 nm) were added as electron acceptors. The colloidal iron oxides were reduced up to 2 orders of magnitude more rapidly (up to 1,255 pmol h− 1 cell− 1) than bulk macroaggregates of the same iron phases (6 to 70 pmol h− 1 cell− 1). The increased reactivity was not only due to the large surface areas of the colloidal aggregates but also was due to a higher reactivity per unit surface. We hypothesize that this can be attributed to the high bioavailability of the nanosized aggregates and their colloidal suspension. Furthermore, a strong enhancement of reduction rates of bulk ferrihydrite was observed when nanosized ferrihydrite aggregates were added.

Effects and mechanisms of modified biochars on microbial iron reduction of Geobacter sulfurreducens

Chemosphere ◽  
2021 ◽  
pp. 130983
Author(s):  
Yue Lu ◽  
Yingju Hu ◽  
Lin Tang ◽  
Qingqing Xie ◽  
Qian Liu ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Geobacter Sulfurreducens ◽  
Microbial Iron Reduction

scholarly journals Colloidal Iron Oxide Formulation for Equine Hoof Disinfection

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 766
Author(s):  
Maurizio Isola ◽  
Cristina Piccinotti ◽  
Massimiliano Magro ◽  
Luca Fasolato ◽  
Fabio Vianello ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Colloidal Suspension ◽  
Bacterial Load ◽  
Inhibitory Effect ◽  
In Vitro Assays ◽  
Resistant Bacteria ◽  
Colloidal Iron ◽  
In Vivo Test

The presence of bacteria of various origins on horse hoofs enables the onset of infections following trauma or even post-surgical wounds. Thus, the analysis of new antibacterial substances is of fundamental importance. In this study, the antibacterial efficacy of Iron Animals (IA), a stable colloidal suspension of iron oxide, organic acids, and detergents, was tested in vitro and in vivo. In vitro assays were performed to test the unspecific inhibitory effect of IA on both gram-positive and gram-negative bacteria monitoring the microorganism growth by spectrophotometry (optical density OD600) at 37 °C for 24 h. In vivo test consists on the quantification of the bacterial load in colony forming units per gram (CFU/g) of specimens collected from the frog region of the anterior hooves of 11 horses. Sampling followed the application of four disinfectant protocols consisting of two consecutive 3 min scrubs with 50 mL of 10% Povidone-iodine (PI) or 4% Chlorhexidine (CHx), with or without an additional application for 15 min of 10 mL of Iron Animals (PI+IA and CHx+IA). In vitro, IA completely suppressed the bacterial growth of all the tested microorganisms, resulting in effectiveness also against CHx-resistant bacteria, such as Staphylococcus aureus. In vivo, PI emerged as an ineffective protocol; CHx was effective in 18% of cases, but with the addition of IA (CHx + IA) its use emerged as the best disinfectant protocol for horse hoof, achieving the lowest bacterial load in 55% of cases. The addition of IA, after PI or CHx, improves the effectiveness of both disinfectants leading to the highest bactericidal activity in 82% of cases.

Photoassisted dissolution of colloidal iron oxides by thiol-containing compounds

1986 ◽  
Vol 112 (2) ◽  
pp. 412-420 ◽  
Author(s):  
T.David Waite ◽  
Alex Torikov ◽  
J.David Smith
Keyword(s):  
Iron Oxides ◽  
Colloidal Iron

scholarly journals Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryosuke Sinmyo ◽  
Elena Bykova ◽  
Sergey V. Ovsyannikov ◽  
Catherine McCammon ◽  
Ilya Kupenko ◽  
...  
Keyword(s):  
Applied Sciences ◽  
Crystal Structure ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Industrial Applications ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Insight Into

Abstract Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

Waste Plastic Sachet as Alternative Anti-Corrosion Filler for Iron Oxide in Resin Coatings

2021 ◽  
Vol 877 ◽  
pp. 9-14
Author(s):  
Francis Darwin T. Eugenio ◽  
Bryan B. Pajarito
Keyword(s):  
Corrosion Resistance ◽  
Iron Oxide ◽  
Film Thickness ◽  
Iron Oxides ◽  
Water Resistance ◽  
Inorganic Compounds ◽  
Environmental Issues ◽  
Metal Coatings ◽  
Waste Plastic ◽  
Coating Mixture

Iron oxides and similar inorganic compounds have served as anti-corrosion fillers for metal coatings. Environmental issues related to the mining of metallic fillers have stimulated interest in alternative fillers such as organic fillers. This paper explores the use of comminuted waste plastic sachets (WPS) as an anti-corrosion filler to resin-based metal coating. Mixture design of experiment was used to study the effect of iron oxide-WPS blends on the film thickness, viscosity, corrosion behavior, and water resistance of the coating. Results show that the film thickness was affected by the presence of iron oxide while the viscosity of the coating was affected by high loads of WPS. Among all coatings, the blend containing 25% iron oxide and 75% WPS produced the highest corrosion resistance. In conclusion, comminuted WPS provided additional corrosion resistance and could serve as an alternative anti-corrosion filler.

scholarly journals Morphological Analysis of Quartz Grains of Two Horizons in a Ultisol, Paraná – Brazil (Análise morfológica de grãos de quartzo de dois horizontes de Argissolos, Paraná – Brasil)

2017 ◽  
Vol 10 (4) ◽  
pp. 1059
Author(s):  
Fabiana Cristina Meira Zaparoli ◽  
Nelson Vicente Lovatto Gasparetto
Keyword(s):  
Iron Oxide ◽  
Surface Morphology ◽  
Iron Oxides ◽  
Morphological Analysis ◽  
Chemical Change ◽  
Subtropical Climate ◽  
Plasma Infusion ◽  
The City ◽  
Quartz Grains ◽  
Bt Horizon

This research aimed to compare the surface morphology of quartz grains of the E and Bt horizons of an Ultisol of the Aratu stream basin, in the city of Floraí, Paraná. The Ultisol is derived from sandstones of the Caiuá Formation and it is subjected to mesothermal humid subtropical climate. The materials from the E horizon showed abundant porosity compared to the Bt horizon ones, due to the filling of pores by coating of clay and iron oxides. On the surface of the quartz grains of the E horizon, several features were identified such as ";craters";, pyramidal microfeatures, gulfs of dissolution, elongated cavities, and silica reprecipitation, resulting from the chemical change, and fragmented grains resulting from a phenomenon called ";plasma infusion."; In the Bt horizon, nearly all the detrital grains were surrounded by clay and iron oxide. The detrital grains of the Bt horizon were better preserved, showing little corrosion features and rare fragmented grains, compared to the E horizon. These analyzes showed that the water flow accounts for the superficial alteration of detrital quartz grains when they are under the influence of humid subtropical climate.  R E S U M OA pesquisa teve como objetivo comparar a morfologia superficial de grãos de quartzo dos horizontes E e Bt de um Argissolo da bacia do córrego Aratu, no município de Floraí, PR. O Argissolo é derivado de arenitos da Formação Caiuá e submetido a clima subtropical úmido mesotérmico. Os materiais do horizonte E apresentam porosidade abundante quando comparados com os do horizonte Bt, em razão do preenchimento dos poros por revestimentos de argila e óxidos de ferro. Foram identificadas na superfície dos grãos de quartzo do horizonte E várias feições tipo “crateras”, microfeições piramidais, golfos de dissolução, cavidades alongadas, reprecipitação de sílica, oriundas da alteração química, e grãos fragmentados devido ao fenômeno denominado “plasma infusion”. No horizonte Bt, praticamente todos os grãos detritais estão envolvidos por argila e óxidos de ferro. Os grãos detritais do horizonte Bt estão mais preservados, exibindo poucas feições de corrosão e raros grãos fragmentados, se comparados com os do horizonte E. Essas análises demonstraram que o fluxo hídrico é o responsável pela alteração superficial dos grãos detritais de quartzo quando sob a influência de clima subtropical úmido. Palavras-chave: Argissolo, morfologia de grãos de quartzo, alteração geoquímica, fluxo hídrico 

scholarly journals Iron Oxide Contents in Relation to the Colour of Asnawa Soils

2017 ◽  
Vol 1 (1) ◽  
pp. 89-94
Author(s):  
Sherwan Kafoor
Keyword(s):  
Iron Oxide ◽  
Soil Properties ◽  
Iron Oxides ◽  
Soil Samples ◽  
Visual Methods ◽  
Colour Intensity ◽  
Fe Oxide ◽  
Fe Oxides ◽  
New Formula

Asnawa soils contain high amounts of iron oxides. These minerals apply much influence on different soil properties, of which the most observable is colour. The objective of this study was to conclude if colour of soils measured by visual methods can be parameterized to quantify soil Fe oxides. The examined area was divided to three zones (zone A, zone B and zone C) according to their colour intensity. Forty soil samples were examined for their colour and iron oxide contents. Their colour were ranged between 5YR (H) 2.5 (V/C) to 5YR (H) 5/8 (V/C). The average values of free Fe oxide in the soils of the three zones were 52.1%, 36.8% and 15.9% respectively. A new formula was derived to measure colour intensity. A highly significant correlation was found between colour intensity and concentrations of Fe oxides in the examined soils.

Facilitated Heterogeneous Photodegradation of Dissolved Organic Matter by Particulate Iron

2004 ◽  
Vol 1 (3) ◽  
pp. 197 ◽  
Author(s):  
Julia A. Howitt ◽  
Darren S. Baldwin ◽  
Gavin N. Rees ◽  
Barry T. Hart
Keyword(s):  
Organic Matter ◽  
Iron Oxide ◽  
Dissolved Organic Matter ◽  
Iron Oxides ◽  
Aquatic Ecosystems ◽  
Photochemical Reactions ◽  
Freshwater Systems ◽  
Particulate Iron ◽  
Presence And Absence ◽  
Australian Freshwater

Environmental Context. Iron oxides, as suspended minerals or as a colloidal phase, are common in Australian freshwater systems. Freshwater systems are also loaded with carbon-based substances, ‘dissolved organic matter’, but not all is biologically available as food to freshwater organisms. However, photochemical interactions between these iron oxides and dissolved organic matter provide a mechanism for biologically resistant carbon to re-enter the food web. Suspended iron oxides thus need to be considered in carbon cycles in aquatic ecosystems. Abstract. The photochemical degradation of dissolved organic matter (DOM) derived from the leaves of River Red Gum (Eucalyptus camaldulensis) was examined, with a particular focus on the photochemical generation of CO2, consumption of O2, and the effect of particulate iron minerals on these photochemical reactions. Solutions of leaf leachate were irradiated with ultraviolet and visible light in the presence and absence of amorphous iron oxides. Addition of fresh iron oxide was found to increase the rate of photodegradation of the organic matter by up to an order of magnitude compared to the reactions without added iron oxide. The ratio of CO2 produced to O2 consumed was ~1:1 in both the presence and absence of iron oxyhydroxide. The reactivity of the iron oxides was dependent on the preparation method and decreased with increased storage time. These results suggest that photochemical reactions on particle surfaces should be considered when examining carbon transformation in aquatic ecosystems, especially at sites with potential for the production of iron oxyhydroxides.

Sign in / Sign up

Export Citation Format

Share Document