Hematite phosphate adsorption

Barron,V. Herruzo, M. Torrent, J. (1988) Phosphate adsorption by aluminous hematites of different shapes. Soil Sci. Soc. Am. J. 52 647-651... 

Colombo, C. Barron,V. Torrent, J. (1994) Phosphate adsorption and desorption in relation to morphology and crystal properties of synthetic hematites. Geochim. Cosmochim. Acta 58 1261-1269... 

The content and type of iron oxide affects soil chemistry. Several workers (e.g., Scheinost and Schwertmann 1995) have shown that phosphate adsorption maxima increase from red (hematitic) to yellow (goethite-rich) soils. Consequently, because yellow soils in some regions are closely correlated to soil P sorption, soil color has been used to predict the likely need for phosphate applications. 

Phosphate Adsorption on Hematite. The presence of P as PO4 at the surface was confirmed in AES by princ al minima occurring near 94 and 110 eV kinetic energy (32). hi addition, the minima occurring at -43 and 52 eV demonstrate that the Fe203 stoichiometry of the thin film oxide was maintained after solution e q)osure. To determine the accumulation of phosphate at the surfece, AES P/Fe intensity ratios were calcmlated fi om measurements of the P(LMM) transition at 110 eV and the Fe(LMM) transition at 651 eV. A plot of this ratio with reaction time (Figure 1) shows that phosphate accumulates rapidly at the sur ce of thin film Fe203 during the first 10 min. 

Pigna M, Colombo C, Violante A (2003) Competitive sorption of arsenate and phosphate on synthetic hematites (in Italian). Proceedings XXI Congress of Societa Italiana Chimica Agraria SICA (Ancona), pp 70-76 Quirk JP (1955) Significance of surface area calculated from water vapour sorption isotherms by use of the B. E. T. equation. Soil Sci 80 423-430 Rancourt DG, Fortin D, Pichler T, Lamarche G (2001) Mineralogical characterization of a natural As-rich hydrous ferric oxide coprecipitate formed by mining hydrothermal fluids and seawater. Am Mineral 86 834-851 Raven K, Jain A, Loeppert, RH (1998) Arsenite and arsenate adsorption on ferrihydrite kinetics, equilibrium, and adsorption envelopes. Environ Sci Technol 32 344-349... 

Various well-known industrial and municipal waste products particularly those from the base metal industry, contain appreciable amounts of Fe oxides which may make them suitable for remediation purposes. Two examples from industry are the residues from the alumina and the titanium industries. The extraction of either Al or Ti from the natural ores (bauxite and ilmenite/rutile, respectively) leaves behind an alkaline and acidic (sulphuric) residue, respectively, in which Fe oxides are enriched, as indicated by their names Red Mud and Red Gypsum . A sample of Red gypsum is reported to contain ca. 35% of Fe oxide consisting of goethite and hematite, half of which was oxalate soluble (Fauziah et al., 1996). As expected, this material had an appreciable adsorption capacity for phosphate and heavy metals and, if added to soils, could confer these properties on them (Peacock Rimmer, 2000),... 

Barron,V Rendon, J.L. Torrent, J. Serna, C.J, (1984) Relation of infrared, crystallochemical, and morphological properties of Al-substi-tuted hematites. Clays Clay Min. 32 475-479 Barrow, J.J. Cox,V.C. (1992) The effects of pH and chloride concentration on mercury sorption. I. Goethite. J. Soil Sci. 43 437-450 Barrow, N. Madrid, L. Posner, A.M. (1981) A partial model for the rate of adsorption and desorption of phosphate by goethite. J. Soil Sci. 32 399-407... 

Acta Cryst. B39 165-170 Pauling, L. Hendricks, S.B. (1925) The crystal structures of hematite and corundum. J. Am. Chem. Soc. 47 781-790 Pauling, L. (1929) The principles of determining the structure of complex ionic crystals. J. Amer. Chem. Soc. 51 289-296 Payne, J.E. Davis, J.A. Waite,T.D. (1996) Uranium adsorption on ferrihydrite — effect of phosphate und humic add. Radiochemica Acta 74 239-243... 

Different from the formation mechanism of titania nanotubes, Fe203 nanotubes are formed by a coordination-assisted dissolution process [95]. The presence of phosphate ions is the crucial factor that induces the formation of a tubular structure, which results from the selective adsorption of phosphate ions on the surfaces of hematite particles and their ability to coordinate with ferric ions. 

Calculations of hydro Q l packing densities for various ces have also been performed for hematite (72). The ces considered theoretically suitable for binuclear bridging complexes of pho hate were the (110), (100), and (223) planes. Calculations of phosphate uptake, assuming a binuclear conoplex, predicted tbat phoq>hate intake for the (110), (100), and (223) planes would be 4.2, 4.8, and 3.6 pmol P m re ectively. Rq>orted values from adsorption studies range from 0.31 - 3.3 pmol P mT (75,14). A reason for the difference between the measured and calculated phosphate... 

For thin film hematite e q>osed to a sodium pho hate solution, initially rapid uptake occurs during the first 10 minutes of solution exposure in ch phosphate conq)letes first layer adsorption. A short induction period ensues, lasting 10 min., which... 

The simple model suggested for the case of the adsorption of labeled sulfate species cannot be unambiguously applied for other anions. For instance, in the case of phosphate anions the pH-dependence of the adsorption of phosphate ions goes through a maximum as shown in Fig. 3 for the case of y-Al203 and hematite [5]. 

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