Journal ArticleDOI
Iron Oxide Removal from Soils and Clays by a Dithionite-Citrate System Buffered with Sodium Bicarbonate
TLDR
In this article, the bicarbonate-buffered Na2S2O4-citrate system was used for removing free iron oxides from latosolic soils, and the least destructive of iron silicate clays.Abstract:
The oxidation potential of dithionite (Na2S2O4) increases from 0.37 V to 0.73 V with increase in pH from 6 to 9, because hydroxyl is consumed during oxidation of dithionite. At the same time the amount of iron oxide dissolved in 15 minutes falls off (from 100 percent to less than 1 percent extracted) with increase in pH from 6 to 12 owing to solubility product relationships of iron oxides. An optimum pH for maximum reaction kinetics occurs at approximately pH 7.3. A buffer is needed to hold the pH at the optimum level because 4 moles of OH are used up in reaction with each mole of Na2S2O4 oxidized. Tests show that NaHCO3 effectively serves as a buffer in this application. Crystalline hematite dissolved in amounts of several hundred milligrams in 2 min. Crystalline goethite dissolved more slowly, but dissolved during the two or three 15 min treatments normally given for iron oxide removal from soils and clays. A series of methods for the extraction of iron oxides from soils and clays was tested with soils high in free iron oxides and with nontronite and other iron-bearing clays. It was found that the bicarbonate-buffered Na2S2O4-citrate system was the most effective in removal of free iron oxides from latosolic soils, and the least destructive of iron silicate clays as indicated by least loss in cation exchange capacity after the iron oxide removal treatment. With soils the decrease was very little but with the very susceptible Woody district nontronite, the decrease was about 17 percent as contrasted to 35–80 percent with other methods.read more
Citations
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Journal ArticleDOI
Determination of illite-smectite structures using multispecimen X-ray diffraction profile fitting
TL;DR: In this paper, a procedure for structural investigations by X-ray diffraction of mixed-layer structures incorporating swelling layers has been developed, which includes I-S minerals from Kazachstan (a rectorite), Dolna Ves in Slovakia, Kinnekulle in Sweden, the North Sea, and Scania in Sweden.
Journal ArticleDOI
Properties of soil kaolinites from south-western Australia
Balwant Singh,Robert Gilkes +1 more
TL;DR: In this paper, the median values for surface area and cation exchange capacity of soil kaolinites are 35 m2 g−1 and 56.7 mmolc kg−1, respectively.
Journal ArticleDOI
Influence of inheritance and pedogenesis on heavy metal distribution in soils of Sicily, Italy
TL;DR: In this paper, various soil types developed from different parent materials in Sicily, Italy, have been analysed in order to compare heavy metal distribution under different geopedological conditions, in relation to the inheritance factor and pedogenic processes.
Journal ArticleDOI
Efficiencies of sediment samplers for wind erosion measurement
TL;DR: In this article, the efficiency of three sediment samplers used for studies of wind erosion was investigated: a vertically integrating trap (an active, modified Bagnold trap for measuring vertically integrated streamwise sediment fluxes, designed for use in a portable wind tunnel); and two single-point, passive traps, the Leach trap and the Fryrear trap (a rugged sampler for field use).
Journal ArticleDOI
Arsenic Speciation and Phytoavailability in Contaminated Soils Using a Sequential Extraction Procedure and XANES Spectroscopy
TL;DR: The results show that As in both fractions was readily available for plant uptake and may pose a potential risk to the environment.
References
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Book
Soil Chemical Analysis
TL;DR: Soil chemical analysis, Soil Chemical Analysis (SCA), this paper, is a technique for soil chemical analysis that is used in the field of Soil Chemistry and Chemical Engineering.
Journal ArticleDOI
Iron Oxide Removal from Soils and Clays1
N. H. Aguilera,M. L. Jackson +1 more
TL;DR: In this article, a procedure is presented which employs sodium dithionite (Na2S2O4, hyposulfite, or "hydrosulfite") as the reductor, and 0.3 molar citrate with or without Fe-3 specific Versene as the chelating reagent.