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
Technogenic soils developed on mine spoils containing iron sulphides: Mineral transformations as an indicator of pedogenesis
Łukasz Uzarowicz,S. Skiba +1 more
TL;DR: In this article, the authors used X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometry (SEM-EDS) techniques, and selective extraction methods were applied in the examination of soil mineralogy.
Journal ArticleDOI
Chemical and isotopic investigations into the origin of clay minerals from the Galapagos hydrothermal mounds field
TL;DR: A dark green authigenic nontronite is the major component of the Galapagos hydrothermal mounds field sediments, and its isotopic compositions of the chemically purified, in situ mounds temperatures of up to 15°C are calculated in this article.
Journal ArticleDOI
Mobility of Cr, Pb, Cd, Cu and Zn in a loamy sand soil: a comparative study
Bruna Fonseca,Hugo Figueiredo,Joana Lúcia Lima Correia Rodrigues,A.M. Queiroz,Teresa Tavares +4 more
TL;DR: In this paper, the authors evaluate the scenario of co-contamination of a loamy sand soil by multiple heavy metals, including Cr, Pb, Cd, Cu and Zn.
Journal ArticleDOI
Application of iron electrode corrosion enhanced electrokinetic-Fenton oxidation to remediate diesel contaminated soils: A laboratory feasibility study
TL;DR: In this paper, the efficiency of electrokinetic (EK) by using different electrode materials (graphite and iron rods) and electrolytes (tap water, 0.01 m NaCl, and 0.1m NaCl) on the remediation of diesel contaminated soils was evaluated.
Journal ArticleDOI
Loss of phosphorus from soil in semi-arid northern Tanzania as a result of cropping: evidence from sequential extraction and 31P-NMR spectroscopy
Dawit Solomon,Johannes Lehmann +1 more
TL;DR: In this article, the effects of land use changes on the amount and structural composition of P in the soil were investigated using sequential extraction and 31P-NMR, and it was shown that clearing and continuous cultivation reduced both organic and inorganic P in soil.
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.