Microbial degradation of organic carbon sorbed to phyllosilicate clays with and without hydrous iron oxide coating

2014 ◽  
Vol 66 (1) ◽  
pp. 83-94 ◽  
Author(s):  
A. R. Saidy ◽  
R. J. Smernik ◽  
J. A. Baldock ◽  
K. Kaiser ◽  
J. Sanderman
Keyword(s):  
Iron Oxide ◽  
Organic Carbon ◽  
Microbial Degradation ◽  
Oxide Coating ◽  
Hydrous Iron Oxide ◽  
Phyllosilicate Clays

Surface fractal dimensions of synthetic clay-hydrous iron oxide associations from nitrogen adsorption isotherms and mercury porosimetry

Clay Minerals ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 355-363 ◽  
Author(s):  
R. Cells ◽  
J. Cornejo ◽  
M. C. Hermosin
Keyword(s):  
Fractal Dimension ◽  
Iron Oxide ◽  
Adsorption Isotherms ◽  
Mercury Porosimetry ◽  
Oxide Coating ◽  
Nitrogen Adsorption ◽  
Medium Size ◽  
Surface Fractal ◽  
Hydrous Iron Oxide ◽  
Nitrogen Adsorption Isotherms

AbstractModel associations of layer silicates (kaolinite and montmorillonite) and iron oxyhydroxides were obtained by precipitating hydrous iron oxide in clay suspensions at different loading. The porosity of these clay-hydrous iron oxide associations was studied in the macro- and mesopore range by mercury intrusion porosimetry (MIP) and in the micropore region by nitrogen adsorption isotherms, being the fractal geometry applied to the approaches used in porosity studies. Results of nitrogen adsorption isotherms showed that surface area and microporosity of kaolinite and montmorillonite increased upon Fe precipitation, especially for montmorillonite. This process is accompanied by an increase in the surface fractal dimension Ds(N2) by the presence of hydrous iron oxide coating the clay particles. Results of MIP also showed a decrease in the pore volume by Fe precipitation on montmorillonite due to a decrease in the number of large pores and a development of new medium-size pores. An increase of the fractal dimension Ds(Hg) was also observed.

The sorption of organic carbon onto differing clay minerals in the presence and absence of hydrous iron oxide

Geoderma ◽  
2013 ◽  
Vol 209-210 ◽  
pp. 15-21 ◽  
Author(s):  
A.R. Saidy ◽  
R.J. Smernik ◽  
J.A. Baldock ◽  
K. Kaiser ◽  
J. Sanderman
Keyword(s):  
Iron Oxide ◽  
Organic Carbon ◽  
Clay Minerals ◽  
Hydrous Iron Oxide ◽  
Presence And Absence

Total organic carbon and the preservation of organic-walled microfossils in Precambrian shale

Geology ◽  
2020 ◽  
Author(s):  
C.R. Woltz ◽  
S.M. Porter ◽  
H. Agić ◽  
C.M. Dehler ◽  
C.K. Junium ◽  
...  
Keyword(s):  
Species Richness ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Microbial Degradation ◽  
Sedimentation Rate ◽  
Surface Pattern ◽  
Causal Factors ◽  
Eukaryotic Diversity ◽  
High Concentrations ◽  
Fossil Preservation

Much of our understanding of early eukaryote diversity and paleoecology comes from the record of organic-walled microfossils in shale, yet the conditions controlling their preservation are not well understood. It has been suggested that high concentrations of total organic carbon (TOC) inhibit the preservation of organic fossils in shale, and although this idea is supported anecdotally, it has never been tested. Here we compared the presence, preservational quality, and assemblage diversity of organic-walled microfossils to TOC concentrations of 346 shale samples that span the late Paleoproterozoic to middle Neoproterozoic in age. We found that fossil-bearing samples have significantly lower median TOC values (0.32 wt%, n = 189) than those containing no fossils (0.72 wt%, n = 157). Preservational quality, measured by the loss of surface pattern, density of pitting, and deterioration of wall margin, decreases as TOC increases. Species richness negatively correlates with TOC within the ca. 750 Ma Chuar Group (Arizona, USA), but no relationship is observed in other units. These results support the hypothesis that high TOC content either decreases the preservational quality or inhibits the preservation of organic-walled microfossils altogether. However, it is also possible that other causal factors, including sedimentation rate and microbial degradation, account for the correlation between fossil preservation and TOC. We expect that as TOC varies in space and time, so too does the probability of finding well-preserved fossils. A compilation of 13,940 TOC values spanning Earth history suggests significantly higher median TOC levels in Mesoproterozoic versus Neoproterozoic shale, potentially biasing the interpreted pattern of increased eukaryotic diversity in the Tonian.

Dietary Uptake of Cu Sorbed to Hydrous Iron Oxide is Linked to Cellular Toxicity and Feeding Inhibition in a Benthic Grazer

2016 ◽  
Vol 50 (3) ◽  
pp. 1552-1560 ◽  
Author(s):  
Daniel J. Cain ◽  
Marie-Noële Croteau ◽  
Christopher C. Fuller ◽  
Amy H. Ringwood
Keyword(s):  
Iron Oxide ◽  
Cellular Toxicity ◽  
Feeding Inhibition ◽  
Dietary Uptake ◽  
Hydrous Iron Oxide

Kinetics, adsorption and desorption of Cd(II) and Cu(II) on natural allophane: Effect of iron oxide coating

Geoderma ◽  
2018 ◽  
Vol 319 ◽  
pp. 70-79 ◽  
Author(s):  
Jorge Silva-Yumi ◽  
Mauricio Escudey ◽  
Manuel Gacitua ◽  
Carmen Pizarro
Keyword(s):  
Iron Oxide ◽  
Oxide Coating ◽  
Adsorption And Desorption

scholarly journals Selenate Adsorption from Water Using the Hydrous Iron Oxide-Impregnated Hybrid Polymer

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1630
Author(s):  
Vesna Marjanovic ◽  
Aleksandra Peric-Grujic ◽  
Mirjana Ristic ◽  
Aleksandar Marinkovic ◽  
Radmila Markovic ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Adsorption Capacity ◽  
Ph Value ◽  
Xrd Analysis ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Adsorbent Regeneration ◽  
Desorption Efficiency ◽  
Hydrous Iron Oxide ◽  
The Cross

Hybrid adsorbent, based on the cross-linked copolymer impregnated with hydrous iron oxide, was applied for the first time for Se(VI) adsorption from water. The influence of the initial solution pH, selenate concentration and contact time to adsorption capacity was investigated. Adsorbent regeneration was explored using a full factorial experimental design in order to optimize the volume, initial pH value and concentration of the applied NaCl solution as a reagent. Equilibrium state was described using the Langmuir model, while kinetics fitted the pseudo-first order. The maximum adsorption capacity was found to be 28.8 mg/g. Desorption efficiency increased up to 70%, and became statistically significant with the reagent concentration and pH increase, while the applied solution volume was found to be insignificant in the investigated range. Based on the results obtained, pH influence to the adsorption capacity, desorption efficiency, Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis of loaded adsorbent, it was concluded that the outer- and inner-sphere complexation are mechanisms responsible for Se(VI) separation from water. In addition to the experiments with synthetic solutions, the adsorbent performances in drinking water samples were explored, showing the purification efficiency up to 25%, depending on the initial Se(VI) concentration and water pH. Determined sorption capacity of the cross-linked copolymer impregnated with hydrous iron oxide and its ability for regeneration, candidate this material for further research, as a promising anionic species sorbent.

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