Molecular Models of Metal Sorption on Clay Minerals

2015 ◽  
pp. 143-194
Author(s):  
Randall T. Cygan
Keyword(s):  
Clay Minerals ◽  
Molecular Models ◽  
Metal Sorption

scholarly journals Effect of pedogenic iron-oxyhydroxide removal on the metal sorption by soil clay minerals

2021 ◽  
Vol 21 (4) ◽  
pp. 1785-1799
Author(s):  
Péter Sipos ◽  
Viktória Kovács Kis ◽  
Réka Balázs ◽  
Adrienn Tóth ◽  
Tibor Németh
Keyword(s):  
Clay Minerals ◽  
Close Association ◽  
Direct Analysis ◽  
Alkaline Soil ◽  
Mineral Surfaces ◽  
Iron Oxyhydroxide ◽  
Metal Sorption ◽  
Before And After ◽  
Fe Oxyhydroxides ◽  
Cu And Zn

Abstract Purpose The close association of Fe-oxyhydroxides and clay minerals might influence the sorption properties of these components. We aimed to study the effect of removing the pedogenic Fe-oxyhydroxides on the sorption of Cd, Cu, Pb, and Zn by the clay mineral particles in soils with contrasting pH. Methods Competitive batch sorption experiments before and after Fe-oxyhydroxide extraction in soils were carried out together with the direct analysis of the metal sorption on individual particles of ferrihydrite, smectite, and illite/smectite by TEM. Results Ferrihydrite was a more effective metal sorbent than clay minerals, although its removal resulted in decreased sorption only for Cd, Cu, and Zn. Ferrhydrite coating blocked metals’ access for certain sorption sites on clay surfaces, which were only accessible for Pb as the most efficient competitor after removing the coating. This observation was the most remarkable for the smectite particles in the alkaline soil. Mineral surfaces sorbed higher Cu than Pb concentrations and higher Zn than Cd concentrations despite the former metals’ lower bulk sorption. Thus, organic surfaces and precipitation contributed to Pb and Cd’s retention to a greater extent than for Cu and Zn. The structural Fe of smectite also promoted the metal sorption in both soils. Conclusion Removal of iron-oxyhydroxide coatings from the soil affects metal sorption selectively. Direct study of metal sorption on individual soil particles enables us to gain a more in-depth insight into soil minerals’ role in this process.

Heavy Metal Sorption on Clay Minerals Affected by the Siderophore Desferrioxamine B

2000 ◽  
Vol 34 (13) ◽  
pp. 2749-2755 ◽  
Author(s):  
Uta Neubauer ◽  
Bernd Nowack ◽  
Gerhard Furrer ◽  
Rainer Schulin
Keyword(s):  
Heavy Metal ◽  
Clay Minerals ◽  
Metal Sorption ◽  
Desferrioxamine B ◽  
Heavy Metal Sorption

Hydrated form of some clay minerals observed using a film sealed environmental cell

1978 ◽  
Vol 36 (1) ◽  
pp. 72-73
Author(s):  
N. Kohyama ◽  
K. Fukushima ◽  
A. Fukami
Keyword(s):  
Clay Minerals ◽  
Morphological Changes ◽  
Carbon Film ◽  
Electron Microscopic Observation ◽  
Adsorbed Water ◽  
Electron Microscopic ◽  
Hydrated Form ◽  
Thin Carbon ◽  
Environmental Cell ◽  
Thin Carbon Film

Since the interlayer or adsorbed water of some clay minerals are quite easily dehydrated in dried air, in vacuum, or at moderate temperatures even in the atmosphere, the hydrated forms have not been observed by a conventional electron microscope(TEM). Recently, specific specimen chambers, “environmental cells(E.C.),” have been developed and confirmed to be effective for electron microscopic observation of wet specimen without dehydration. we observed hydrated forms of some clay minerals and their morphological changes by dehydration using a TEM equipped with an E.C..The E.C., equipped with a single hole copper-microgrid sealed by thin carbon-film, attaches to a TEM(JEM 7A) with an accelerating voltage 100KV and both gas pressure (from 760 Torr to vacuum) and relative humidity can be controlled. The samples collected from various localities in Japan were; tubular halloysite (l0Å) from Gumma Prefecture, sperical halloysite (l0Å) from Tochigi Pref., and intermediate halloysite containing both tubular and spherical types from Fukushima Pref..

Colloidal systems in soils

1994 ◽  
Vol 52 ◽  
pp. 64-65
Author(s):  
J. Thieme ◽  
J. Niemeyer ◽  
P. Guttman
Keyword(s):  
Clay Minerals ◽  
Polymeric Materials ◽  
Spatial Arrangement ◽  
High Specific Surface Area ◽  
Turnover Rates ◽  
Colloidal Systems ◽  
Chemical Conditions ◽  
Aggregation Phenomena ◽  
Iron And Manganese ◽  
Soil Colloids

In soil science the fraction of colloids in soils is understood as particles with diameters smaller than 2μm. Clay minerals, aquoxides of iron and manganese, humic substances, and other polymeric materials are found in this fraction. The spatial arrangement (microstructure) is controlled by the substantial structure of the colloids, by the chemical composition of the soil solution, and by thesoil biota. This microstructure determines among other things the diffusive mass flow within the soils and as a result the availability of substances for chemical and microbiological reactions. The turnover of nutrients, the adsorption of toxicants and the weathering of soil clay minerals are examples of these surface mediated reactions. Due to their high specific surface area, the soil colloids are the most reactive species in this respect. Under the chemical conditions in soils, these minerals are associated in larger aggregates. The accessibility of reactive sites for these reactions on the surface of the colloids is reduced by this aggregation. To determine the turnover rates of chemicals within these aggregates it is highly desirable to visualize directly these aggregation phenomena.

Mineral nitrogen isotope signature in clay minerals formed under high ammonium environment conditions in sediment associated with ammonium-rich sediment-hosted hydrothermal system

2018 ◽  
Vol 52 (4) ◽  
pp. 317-333 ◽  
Author(s):  
Jaeguk Jo ◽  
Toshiro Yamanaka ◽  
Tomoki Kashimura ◽  
Yusuke Okunishi ◽  
Yoshihiro Kuwahara ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Hydrothermal System ◽  
Nitrogen Isotope ◽  
Mineral Nitrogen ◽  
Isotope Signature
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