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
Nickel Hyperaccumulation by Brassicaceae in Serpentine Soils of Albania and Northwestern Greece
Aida Bani,Aida Bani,Guillaume Echevarria,Alfred Mullaj,Roger D. Reeves,Jean-Louis Morel,Sulejman Sulçe +6 more
TL;DR: The objectives of this study were to understand the potential of Ni hyperaccumulation of these species in close relation with the characteristics of their native soil environments, and to identify a new member in the Albanian Ni-hyperaccumulator flora.
Journal ArticleDOI
Responses of soil phosphorus fractions after nitrogen addition in a subtropical forest ecosystem: Insights from decreased Fe and Al oxides and increased plant roots
Yuexin Fan,Xiaojian Zhong,Fang Lin,Chenchung Liu,Liuming Yang,Minhuang Wang,Guangshui Chen,Yuehmin Chen,Yusheng Yang +8 more
TL;DR: Wang et al. as discussed by the authors studied a natural Castanopsis carlesii forest in Fujian, China subjected to 3 years of N addition and found that N application remarkably increased the concentrations of soil available P but significantly decreased content of soil moderately labile P.
Journal ArticleDOI
Application of electron paramagnetic resonance and mossbauer spectroscopy in the investigation of kaolinite-group minerals
TL;DR: In this article, the authors used X-band electron paramagnetic resonance (EPR) and Mbssbauer spectroscopy to investigate the properties of nacrite, dickite, kaolinite, and halloysite.
Journal ArticleDOI
Organic matter characteristics and distribution in Ferralsol profiles of a climosequence in southern Brazil
Ricardo Simão Diniz Dalmolin,C. N. Gonçalves,Deborah Pinheiro Dick,Heike Knicker,E. Klamt,Ingrid Kögel-Knabner +5 more
TL;DR: In this paper, the authors studied the impact of climate, soil texture and iron mineralogy on the content and composition of organic matter in Ferralsols along a climosequence in southern Brazil.
Journal ArticleDOI
Effect of bauxite properties on the settling of red mud
Loretta Y. Li,G.K. Rutherford +1 more
TL;DR: In this article, a total of 7 bauxites and 7 red muds from Southern Brazil are examined for their mineralogical, chemical and physical properties by employing X-ray diffraction (XRD), XRF, dissolution technique (dithionite-citrate), inductively coupled plasma (ICP) and, Brunauer, Emmett and Teller (B.E.T.) specific surface area, for comparison with the measured settling behaviour of the muds.
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.