Journal ArticleDOI
Competitive Sorption of Arsenate and Phosphate on Different Clay Minerals and Soils
Antonio Violante,Massimo Pigna +1 more
TLDR
In this article, the competitive sorption of PO 4 and AsO 4 on selected phyllosilicates, metal oxides, synthetic organo-mineral complexes, and soil samples as affected by pH (4.0-8.0), ligands concentration, surface coverage of the oxyanions on the samples and the residence time.Abstract:
Sorption and desorption of AsO 4 on or from different soil components may have a dominant role in regulating As mobility in soils. The objectives of this work were to provide information on the factors that influence the competitive sorption of AsO 4 and PO 4 in soil. We studied the competitive sorption of PO 4 and AsO 4 on selected phyllosilicates, metal oxides, synthetic organo-mineral complexes, and soil samples as affected by pH (4.0-8.0), ligands concentration, surface coverage of the oxyanions on the samples and the residence time. We found that Mn, Fe, and Ti oxides and phyllosilicates particularly rich in Fe (nontronite, ferruginous smectites) were more effective in sorbing AsO 4 than PO 4 . In fact, by adding AsO 4 and PO 4 as a mixture (AsO 4 /PO 4 molar ratio of 1) more AsO 4 , than PO 4 was usually sorbed on birnessite, pyrolusite, goethite, nontronite, and ferruginous smectite, but more PO 4 than AsO 4 was sorbed on noncrystalline Al precipitation products, gibbsite, boehmite, allophane, and kaolinite. For example, at pH 5.0 the sorbed AsO 4 /sorbed PO 4 molar ratio (rf) was 1.81 for bimessite, 1.05 for nontronite, but was only 0.45 for kaolinite and 0.14 for allophane. For montmorillonite, illite, and vermiculite the rf values were slightly <1. For soil samples, particularly rich in kaolinite, halloysite, allophane, and containing relatively large amounts of organic C, the rf values were usually much <1. For all the samples, the rf values increased by decreasing the pH and with the residence time of the oxyanions. The sorption of AsO 4 (or PO 4 ) on goethite and gibbsite decreased by increasing the initial PO 4 /AsO 4 (or ASO 4 / PO 4 molar ratio) up to 2.0. However, PO 4 inhibited AsO 4 sorption more on gibbsite than on goethite, whereas AsO 4 prevented PO 4 sorption more on goethite than on gibbsite. The data reported in this paper suggest that the mobility, the bioavailability, and the toxicity of As in soil environments may be greatly affected by the nature of soil components, pH, presence of anions (PO 4 ), and residence time.read more
Citations
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Journal ArticleDOI
Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides.
Antonio G. Caporale,Massimo Pigna,James J. Dynes,Vincenza Cozzolino,Jun Zhu,Antonio Violante +5 more
TL;DR: In this article, the authors described the sorption of arsenate on Al-Mg and Fe -Mg layered double hydroxides as affected by pH and varying concentrations of inorganic and organic ligands.
Journal ArticleDOI
Impact of Redox Conditions on Arsenic Mobilization from Tailings in a Wetland with Neutral Drainage
TL;DR: Arsenic speciation was affected by changes in redox conditions, resulting in rapid mobilization of As during reduction, suggesting that the As transformation was microbially mediated.
Journal ArticleDOI
Competitive sorption-desorption kinetics of arsenate and phosphate in soils
Hua Zhang,H. Magdi Selim +1 more
TL;DR: In this paper, the kinetics of competitive sorption of arsenate (AsO 4 -3 ) and phosphate (PO 4 −3 ) on mineral surfaces has been investigated in batch systems by simultaneously introducing the ligands at different molar ratios.
Journal ArticleDOI
Evaluation of ferrolysis in arsenate adsorption on the paddy soil derived from an Oxisol
TL;DR: Results showed that ferrolysis in an alternating flooding-drying Oxisol-derived paddy soil resulted in a significant decrease of free Iron oxides and increase of amorphous iron oxides in the surface and subsurface layers, and arsenate adsorption was greatly inhibited by increasing suspension pH and incorporation of phosphate.
Journal ArticleDOI
Desorption of arsenic from clay and humic acid-coated clay by dissolved phosphate and silicate
Prasesh Sharma,Andreas Kappler +1 more
TL;DR: The results of this study showed that HA sorption to Ca(2+)-homoionized clay minerals can increase As binding to the clay although the As sorbed to the Clay-HA is also released to a greater extent by competing ions such as phosphate and silicate.
References
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Journal ArticleDOI
Arsenite and Arsenate Adsorption on Ferrihydrite: Kinetics, Equilibrium, and Adsorption Envelopes
TL;DR: In this paper, the authors compared the adsorption behavior of arsenite and arsenate on ferrihydrite, under carefully controlled conditions, with regard to adaption kinetics and the influence of pH.
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Journal ArticleDOI
Arsenic contamination of groundwater and drinking water in Vietnam: a human health threat.
Michael Berg,Hong Con Tran,Thi Chuyen Nguyen,Hung Viet Pham,Roland Schertenleib,Walter Giger +5 more
TL;DR: The high arsenic concentrations found in the tubewells indicate that several million people consuming untreated groundwater might be at a considerable risk of chronic arsenic poisoning.
Journal ArticleDOI
Arsenate and Chromate Retention Mechanisms on Goethite. 1. Surface Structure
TL;DR: In this paper, the authors used Extended X-ray absorption fine structure (EXAFS) spectroscopy to deduce the local coordination environment of two environmental contaminants, arsenate and chromate, on the mineral goethite (α-FeOOH).