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
Effect of citrate-bicarbonate-dithionite treatment on fine-grained magnetite and maghemite
Journal ArticleDOI
Role of Fe oxides in corrosion of pipeline steel in a red clay soil
TL;DR: A series of experiments were conducted to evaluate the effect of Fe oxides on corrosion of pipeline steel in a red clay soil as discussed by the authors, and the results indicated that the corrosivity of the red clay soils greatly relieves after Fe oxide are removed from the soil.
Journal ArticleDOI
Phosphorus retention and availability in three contrasting soils amended with rice husk and corn cob biochar at varying pyrolysis temperatures
Joseph Osafo Eduah,Joseph Osafo Eduah,E. K. Nartey,M. K. Abekoe,Henrik Breuning-Madsen,Mathias Neumann Andersen +5 more
TL;DR: In this article, the effect of corn cob and rice husk biochar on P sorption and desorption in two acid (Typic Plinthustult-A & Plinthic Acrudox-B) and one neutral soil (Quartzipsamment-C).
Journal ArticleDOI
Late Pleistocene glacial chronology of the Pietrele Valley, Retezat Mountains, Southern Carpathians constrained by 10Be exposure ages and pedological investigations
Anne U. Reuther,Petru Urdea,Christian Geiger,Susan Ivy-Ochs,H.-P. Niller,Peter W. Kubik,Klaus Heine +6 more
TL;DR: In this paper, the authors constrain the glacial history of the Pietrele valley in the Retezat Mountains located in the Southern Carpathians and find that the timing of the late Wurmian glacial advance is asynchronous to global climate records, likely reflecting changes in moisture availability in the area.
Journal ArticleDOI
Improved methods for selective dissolution of Mn oxides: applications for studying trace element associations
TL;DR: In this paper, the association of rare earth and other trace elements with Fe and Mn oxides was studied in Fe-Mn-nodules from a lateritic soil from Serra do Navio (Northern Brazil).
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.