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
Experimental alteration of chlorites into vermiculites by chemical oxidation
TL;DR: In this paper, it has been shown that vermiculite adsorbs and retains potassium and ammonium preferentially, which makes it particularly important in exchange reactions involving these cations.
Journal ArticleDOI
Coupling fractionation and batch desorption to understand arsenic and fluoride co-contamination in the aquifer system.
Manish Kumar,Nilotpal Das,Ritusmita Goswami,Kali Prasad Sarma,Prosun Bhattacharya,Al. Ramanathan +5 more
TL;DR: Fe (hydr)oxide fraction was found to play the major role in co-evolution of As and F-.
Journal ArticleDOI
Distribution of zinc fractions and their transformation in submerged rice soils
TL;DR: In this article, the distribution of different forms of Zn in 16 acid alluvial rice growing soils of West Bengal (India) and their transformation on submergence were studied.
Journal ArticleDOI
Sorption, desorption, and degradation of (4-chloro-2-methylphenoxy)acetic acid in representative soils of the Danubian Lowland, Slovakia.
TL;DR: It was shown that MCPA Sorption positively correlated with soil organic carbon content, humic and fulvic acid carbon contents, and negatively with soil pH, and the importance of soil organic matter in MCPA sorption by soils was also confirmed by performing sorption experiments after soilorganic matter removal.
Journal ArticleDOI
Climate and vegetation determine soil organic matter status in an alpine inner-tropical soil catena in the Fan Si Pan Mountain, Vietnam
Pascal Podwojewski,Pascal Podwojewski,Jérôme Poulenard,Minh Luu Nguyet,A. de Rouw,Van Anh T. Nguyen,Quang Ha Pham,Duc Toan Tran +7 more
TL;DR: In this paper, the authors examined the altitudinal variation of soil pedogenesis through 9 selected profiles from the altitude of 1340m to 3143m asl, the summit of the Fan Si Pan mountain, in the north of Vietnam was examined.
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.