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
Adsorption Characteristics of As(III) and As(V) on Alum Sludge from Water Purification Facilities
TL;DR: In this paper, the effectiveness of reusing alum sludge from water purification facilities as adsorbents of As in aqueous systems was examined, and it was shown that the adsorption of As(III and As(V) has rate-limiting steps such as surface diffusion and pore diffusion.
Journal ArticleDOI
Adsorption–Desorption of Arsenate in Three Spanish Soils
TL;DR: In this article, the dynamics of the adsorption of As(V) in three agricultural soils (Xerochrept, Xerofluvent, and Xerorthent) with loamy sand, sandy clay loam, and clay textures, were presented.
Journal ArticleDOI
Adsorption of tungstate (WO4) on birnessite, ferrihydrite, gibbsite, goethite and montmorillonite as affected by pH and competitive phosphate (PO4) and molybdate (MoO4) oxyanions
Tomoe Iwai,Yohey Hashimoto +1 more
TL;DR: In this article, the authors investigated the adsorption characteristics of tungstate (WO 4 ) on soil mineral components and found that WO 4 has higher affinity for clay minerals than PO 4 under acid pH, and than MoO 4 under alkaline pH.
Journal ArticleDOI
Mixed anion (phosphate/oxalate) bonding to iron(III) materials.
TL;DR: The critical role of the templating amine to mediate whether or not the iron(III) is reduced by the organic acid is demonstrated, which will be invaluable for the evaluation of complex environmental systems.
Journal ArticleDOI
Surface Interactions of Arsenite and Arsenate on Soil Colloids
TL;DR: In this article, the authors present a comprehensive view of As adsorption on a range of soil colloidal particles in comparable conditions of pH and ionic strength to allow a direct comparison of surface interactions, including surface charging phenomena.
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.
Journal ArticleDOI
Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate
TL;DR: In this article, the As and Fe K-edges were collected from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages.
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).