Abstract
The acid/base properties of the hematite/water interface and surfacecomplexation with gold has been studied by potentiometric titrations in thefour component system H+ – ≡FeOH –AuCl -4 – Cl-. Equilibrium measurementswere performed in NaCl media at 298.2 K. In the evaluation of equilibriummodel from experimental data the constant capacitance model was applied. Theacid/base properties were investigated in 0.1 M NaCl in the range 2.6 ≤pH ≤ 7.4. The resulting intrinsic constants for protonation anddeprotonation of hydroxyl groups at the surface were logβ s1,1,0,0(int) = 7.10 ± 0.06 andlog β s-1,1,0,0(int) = - 7.80 ±0.06. The density of proton active surface sites was 2.85nm-2 and the specific capacitance 2.5 C V-1 m-2. In the investigation of surface complexation of gold, thepotentiometric titrations were performed in the range 2.0 ≤ pH ≤ 10.2.Titration data was supplemented with analysis of Au in the aqueous phase byatomic absorbance spectrometry. The equilibrium model proposed consists ofthe following monodentate surface complexes: ≡FeOHAuCl3(log β s0,1,1,-1 = 1.45 ± 0.03),≡FeOHAuCl2OH (logβ s-1,1,1,-2 = -3.89 ± 0.02), ≡FeOHAu(OH)3 (logβ s-3,1,1,-4 = -21.94 ± 0.05). Aslightly better fit could be obtained by assuming formation of a bidentatecomplex with the composition(≡FeO)2Au(OH)H2O. However, based onstructural arguments this complex was rejected.
Similar content being viewed by others
References
Baes, C. F., Jr. and Mesmer, R. E. (1976) The Hydrolysis of Cations. J. Wiley & Sons.
Barron, V. and Torrent, J. (1996) Surface hydroxyl configuration of various crystal faces of hematite and goethite. J. Colloid Interface Sci. 177, 407-410.
Brown, A. S. (1934) A type of silver chloride electrode suitable for use in dilute solutions. J. Amer. Chem. Soc. 56, 646-647.
Eggleston, C. M., Hochella, M. F., Stipp, S., and Brown, G. E. (1990) Scanning tunneling microscopy of gold sorbed onto galena. Geol. Soc. Amer. Prog. 22, A292 (abstr.).
Fokkink, L. G. J. (1987) Ion adsorption on oxides. Ph.D. dissertation, Univ. Wageningen.
Fokkink, L. G. J., De Keizer, A., and Lyklema, J. (1989) Temperature dependence of the electrical double layer on oxides: rutile and hematite. J. Colloid Interface Sci. 127, 116-131.
Guneriusson, L. and Sjöberg, S. (1993) Surface complexation in the H+ - Goethite (α-FeOOH) - Hg(II) - Chloride system. J. Colloid Interface Sci. 156, 121-128.
Herbelin, A. L. and Westall, J. C. (1994) FITEQL: A Computer Program for Determination of Chemical Equilibrium Constants from Experimental Data. Version 3.1. Report 94-01. Dept. of Chemistry, Oregon State Univ. Corvallis, OR, USA.
Hiemstra, T., De Wit, J. C. M., and Riemsdijk, W. H. V. (1989) Multisite proton adsorption modeling at the solid/solution interface of (hydr) oxides: A new approach II.Applications to various important (hydr) oxides. J. Colloid Interface Sci. 133, 105-117.
Hyland, M. M. and Bancroft, G. M. (1989) An XPS study of gold deposition at low temperatures on sulphide minerals: Reducing agents. Geochim. Cosmochim. Acta 53, 367-372.
Jean, G. E. and Bancroft, G. M. (1985) An XPS and SEM study of gold deposition at low temperatures on sulphide minerals: Concentration by adsorption/reduction. Geochim. Cosmochim. Acta 49, 979-987.
Kostov, I. (1968) Mineralogy. Oliver & Boyd.
Lövgren, L., Sjöberg, S., and Schindler, P. W. (1990) Acid/base reactions and Al(III) complexation at the surface of goethite. Geochim. Cosmochim. Acta 54, 1301-1306.
Machesky, M. L., Andrade, W. O., and Rose, A. W. (1991) Adsorption of gold (III)-chloride and gold(I)-thiosulfate anions by goethite. Geochim.Cosmochim. Acta 55, 769-776.
Mitsyuk, B. M., Mironov, A. G., Plyusnin, A. M., and Belomestnova, N. V. (1991) Gold uptake by silica from dilute chloride, thiosulfate, and ammoniacal solutions. Geochem. Intl. 28, 852-859.
Nechayev, Ye. A. (1984) The effect of solution composition on the adsorption of gold(III) complexes on hematite. Geochem. Intl. 21, 87-93.
Nechayev, Ye. A. and Nikolenko, N. V. (1986) An adsorption mechanism for supergene gold accumulation. Geochem. Intl. 25, 52-56.
Nechayev, Ye. A. and Zvonareva, G. V. (1983) Adsorption of gold(III) chloride complexes on hematite. Geokhimiya 6, 919-924 (in Russian).
Nilsson, N., Lövgren, L., and Sjöberg, S. (1992). Phosphate complexation at the surface of goethite. Chem. Speciation and Bioavailability. 4, 121-130.
Peck, J. A., Tait, C. D., Swanson, B. I., and Brown, G. E. (1991) Speciation of aqueous gold(III) chlorides from ultraviolet/visible absorption and Raman spectroscopies. Geochim. Cosmochim. Acta 55, 671-676.
Puddephatt, R. J. (1978) The Chemistry of Gold. Elsevier.
Renders, P. J. and Seward, T. M. (1989) The adsorption of thio gold(I) complexes by amorphous As2S3 and Sb2S3 at 25 and 90 C. Geochim. Cosmochim. Acta 53, 255-268.
Sakharova, M. S. and Lobacheva, I. K. (1978) Microgalvanic systems involving sulfides and gold-bearing solutions, and characteristics of gold deposition. Geochem. Intl. 15, 152-157.
Schindler, P. W. and Gamsjäger H. (1972) Acid-base reactions of the TiO2 (anatase)-water interface ant the zero point of charge of TiO2 suspensions. Kolloid-Z u. Z. Polymere 250, 759-765.
Schoonen, M. A. A., Fisher, N. S., and Wente, M. (1992) Gold sorption onto pyrite and goethite: A radiotracer study. Geochim. Cosmochim. Acta 56, 1801-1814.
Sposito, G. (1984) The Surface Chemistry of Soils. Oxford Univ. Press.
Stolyarova, I. A. and Filatova, M. P. (1981) Atomic absorption spectroscopy in analysis of raw minerals.Nedra (in Russian).
Stumm, W. (1992) Chemistry of the Solid-Water Interface. J.Wiley & Sons.
Tossell, J. A. (1996) The speciation of gold in aqueous solution: A theoretical study. Geochim. Cosmochim. Acta 60, 17-29.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Karasyova, O.N., Ivanova, L.I., Lakshtanov, L.Z. et al. Complexation of Gold(III)-Chloride at the Surface of Hematite. Aquatic Geochemistry 4, 215–231 (1998). https://doi.org/10.1023/A:1009622915376
Issue Date:
DOI: https://doi.org/10.1023/A:1009622915376