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
More filters
Journal ArticleDOI
Assessing nickel bioavailability in smelter-contaminated soils
Jeffrey L. Everhart,David H. McNear,Edward Peltier,Daniel van der Lelie,Rufus L. Chaney,Donald L. Sparks +5 more
TL;DR: The combination of plant growth, chemical extraction, and bacterial biosensor approaches are recommended for assessing bioavailability of toxic metals in soil environments derived from industrial pollution.
Journal ArticleDOI
Characteristics and potential pedogenetic processes of a Technosol developing on iron industry deposits
Hermine Huot,Marie-Odile Simonnot,Philippe Marion,Jacques Yvon,Philippe de Donato,Jean Louis Morel +5 more
TL;DR: In this paper, a Technosol developed on purely technogenic materials resulting from an iron industry was thoroughly characterized in order to discuss the pedogenetic evolution of this technosol using knowledge about the pedogenesis of natural soils.
Journal ArticleDOI
Rainfall‐dependent transformations of iron oxides in a tropical saprolite transect of Hainan Island, South China: Spectral and magnetic measurements
TL;DR: In this article, a transect of saprolitic soils from Hainan Island, South China, with high rainfall (1440∼2020 mm/yr), little temperature variation (23∼24°C), and extreme weathering was presented.
Journal ArticleDOI
Intimate association between O/N-alkyl carbon and iron oxides in clay fractions of forest soils
TL;DR: In this article, solid state 13C NMR spectra of clay fractions from A horizons before and after demineralisation with 10% hydrofluoric acid (HF) were used to study selective associations between Fe oxides and functional groups in soil organic matter.
Journal ArticleDOI
Sulfur fractions in particle-size separates of the sub-humid Ethiopian highlands as influenced by land use changes
TL;DR: In this paper, the influence of land use changes on the amount, form and distribution of sulfur (S) in bulk soils and size separates of the sub-humid highlands of southern Ethiopian was investigated.
References
More filters
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.