Goethite oxalate adsorption

Mesuere, K., and W. Fish, Chromate and oxalate adsorption on goethite. 1. Calibration of surface complexation models , Environ. Sci. Technol., 26, 2357-2364 (1992). 

The adsorption of oxalate ions on metal oxides is presented in Figure 5. The adsorption of oxalate ions is characteristic for anion adsorption on metal oxides, and decreases with increasing pH. The following sequence of oxalate adsorption affinity is observed goethite > titania > silica. At the silica/electrolyte interface,... 

Mesuere K, Fish W. (1992b). Chromate and oxalate adsorption on goethite. 2. Surface complexation modelling of competitive adsorption. Environmental Science and Technology 26 2365-2408. 

Liu F, De Cristofaro A, Violante A (2001) Effect of pH phosphate and oxalate on the adsorption/desorption of arsenate on/from goethite. Soil Sci 166 197-208 Livesey NT, Huang PM (1981) Adsorption of arsenate by soils and its relation to selected properties and anions. Soil Sci 131 88-94 Manceau A (1995) The mechanism of anion adsorption on iron oxides Evidence for the bonding of arsenate tetrahedra on free Fe(0, OH)6 edges. Geochim Cosmochim Acta 59 3647-3653. 

Ambe et aL, 1986) and phosphate adsorbed on lepidocrocite raised the adsorption of zinc (Madrid et aL, 1991a). Adsorption of Cd on goethite is increased by sulphate (Hoins et aL, 1993) and by oxalate (Lamy et aL, 1991). 

In addition to oxalate, malonate and citrate accelerate the dissolution of iron oxides in the presence of Fe (Sulzberger et al., 1989). Fe " also promotes the dissolution of magnetite in sulphuric acid (Bruyere Blesa, 1985). Small amounts of Fe in solution speed up the transformation of ferrihydrite to goethite at 50 °C (see Fig. 14.24) by promoting the dissolution of ferrihydrite (Fischer, 1972). Adsorption... 

A second form of storage iron is haemosiderin (Weir et al., 1984). This is deposited in humans as a response to the condition of iron overload. Haemosiderin forms as insoluble granules with electron dense cores surrounded by a protein shell. It exists in two forms primary haemosiderin is the result of iron overload due to excessive adsorption of iron in the gut, whereas the secondary form is caused by the numerous blood transfusions which are used to treat thallassaemia (a form of anaemia). Electron diffraction indicated that the iron core in primary haemosiderin is a 3-line ferrihydrite with magnetic hyperfine splitting only below 4 K and, in the secondary form, consists of poorly ordered goethite. As goethite is less soluble in ammonium oxalate buffer solution (pH 3) it has a lower intrinsic toxicity (Mann et al., 1988). 

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),... 

Atkinson, R.J. (1976) The formation of iron(III) oxide hydroxides from iron(III) oxalate. Aust. J. Chem. 29 2149-2158 Atkinson, R.J. Parfitt, R.L. Smart, R.S.C. (1974) Infrared study of phosphate adsorption on goethite. J. Chem. Soc. Earaday Trans. I. 70 1472-1479... 

Competitive adsorption of sulfate and oxalate on goethite in the absence or presence of phosphate. Soil Sci. 164 180-189... 

The adsorption of oxalate anions onto metal oxide surfaces changes the C, potential in the system. This is shown by data in Figure 6. As one can see, the C, potential for the goethite /electrolyte solution system in the presence of oxalates has negative values in the entire measured pH range for the highest oxalate ions concentration (0.001 M), and decreases with an increase of oxalate ion concentration. 

Figure 8. The adsorption of 0.001 M Cd(II) ions at goethite/electrolyte interface in a presence of oxalate ions (0.001 and 0.002 M).

Lamy, I., Djafer, M., and Terce, M., Influence of oxalic acid on the adsorption of cadmium at the goethite surface. Water Air Soil Poll., 57-58, 457, 1991. 

The adsorption experiments of Cu onto bayerite and goethite in the absence or presence of oxalate were carried out by adding solutions containing suitable quantities of Cu (40 mmol kg ) to 100 mg of each sorbent in a volume of 9.7 mL (0.02 mol L i). The samples were kept for 4 h at a constant pH (3.0-7.0) and the final suspensions were brought at 10 mL. The final suspensions were centrifuged at... 

Zhou, D., De Cristofaro, A., He, J.Z., Violante, A., 1999. Effect of oxalate on adsorption of copper on goethite, bayerite and kaolinite. In Kodama, H., Mermut, A.R., Torrance, J.K. (Eds.), Clays for our Future. Proceedings 11th International Clay Conference, Ottawa, Canada, 1977, pp. 523-529. 

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