Solubility and Stability of Calcium Arsenates at 25∘C
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
The solubility and stability of calcium arsenates at 25 ∘C was determined by both precipitation and dissolution experiments. Ca3(AsO4)2⋅ 3H2O(c), Ca3(AsO4)2⋅ 21/4H2O(c), Ca5(AsO4)3(OH)(c) and Ca4(OH)2(AsO4)2⋅ 4H2O(c) were identified in our experiment over a wide range of pH and for Ca/As molar ratios between 1.25 and 4.0. The solids precipitated at pH = 3 ∼ 7 and Ca/As = 1.5 were phase-pure and well-crystallized Ca3(AsO4)2⋅ xH2O(c) and had relatively larger grain size than those formed at pH > 7. Based on the analytical results and using the computer program PHREEQC, the solubility products for Ca3(AsO4)2⋅ 3H2O(c), Ca3(AsO4)2⋅ 21/4H2O(c), Ca5(AsO4)3(OH)(c) and Ca4(OH)2(AsO4)2⋅ 4H2O(c) were calculated as K sp of 10− 21.14(10− 20.01 ∼ 10− 22.02), 10− 21.40(10− 20.08 ∼ 10− 21.98), 10− 40.12(10− 37.53 ∼ 10− 42.72) and 10− 27.49(10− 26.10 ∼ 10− 28.91), respectively. Correspondingly, the free energies of forming (Δ G f o ) of these calcium arsenates were calculated to be −3787.87 kJ/mol, −3611.50 kJ/mol, −5096.47 kJ/mol and −4928.86 kJ/mol.
- Bothe, J. V. and Brown P. W.: 1999a, ‘Arsenic immobilization by calcium arsenate formation’, Environ. Sci. Technol. 33, 3806–3811. CrossRef
- Bothe, J. V., and Brown, P. W.: 1999b, ‘The stabilities of calcium arsenates at 23±1∘C’, J. Hazard. Mater. B69, 197–207.
- Chukhlantsev, V.: 1956, ‘Solubility products of arsenates’, Zhurnal Neorganicheskoi Khmii (J. Inorg. Chem.-USSR) 1, 1975–1982.
- Donahue, R. and Hendry, M. J.: 2003, ‘Geochemistry of arsenic in uranium mine mill tailings, Saskatchewan, Canada’, Appl. Geochem. 18, 1733–1750. CrossRef
- Essington, M. E.: 1988, ‘Solubility of barium arsenate’, Soil Sci. Soc. Am. J. 52, 1566–1570.
- Fulladosa, E., Murat, J. C., Martinez, M. and Villaescusal, I.: 2004, ‘Effect of pH on arsenate and arsenite toxicity to luminescent bacteria (Vibrio fischeri)’, Arch. Environ. Contam. Toxicol. 46, 176–182.
- Karagas, M. R., Le, C. X., Morris, S., Blum, J., Lu, X., Spate, V.: 2001 ‘Markers of low level arsenic exposure for evaluating human cancer risks in the US population’, Int. J. Occup. Med. Environ. Health 14, 171–175.
- Kittrick, J. A., and F. J. Peryea.: 1986, ‘Determination of the Gibbs free energy of formation of magnesite by solubility methods’, Soil Sci. Soc. Am. J. 50, 243–247. CrossRef
- Magalhães, M. C. F.: 2002, ‘Arsenic - An environmental problem limited by solubility’, Pure Appl. Chem. 74, 1843–1850.
- Mahapatra, P. P., Mahapatra, L. M. and Mishra, B.: 1986, ‘Solubility of calcium hydrogen arsenate in aqueous medium’, Indian. J. Chem. 25A, 647–9.
- Mihaljevic, M., Ponavic, M., Ettler, V. and Šebek, O.: 2003, ‘A comparison of sequential extraction techniques for determining arsenic fractionation in synthetic mineral mixtures’, Anal. Bioanal. Chem. 377, 723–729. CrossRef
- Nishimura, T. and Robins, R. G.: 1998, ‘A re-evaluation of the solubility and stability regions of calcium arsenites and calcium arsenates in aqueous solution at 25∘C’, Mineral Proc. and Extr. Met. Reviews 18, 283–308.
- Nishimura, T. and Tozawa, K.: 1978, ‘On the solubility products of ferric, calcium and magnesium arsenates’, Bull. Res. Inst. Min. Dress. Metall. Tohoku Univ. 34(1), 19–26.
- Nishimura, T. and Tozawa, K.: 1984, ‘The reaction for the removal of As(III) and As(V) from aqueous solutions by adding calcium hydroxide’, J. Min. Met. Inst. Japan 100, 1085–1091.
- Nishimura, T. and Tozawa, K.: 1985, ‘Removal of arsenic from waste water by addition of calcium hydroxide and stabilization of arsenic-bearing precipitate by calcination’, In A. J. Oliver (ed.), Impurity Control Disposal, Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, Canada, pp.3/1–3/18.
- Nishimura, T., Tozawa, K. and Robins, R. G.: 1983, ‘The calcium-arsenic-water system’, proceedings MMIJ/Aus.IMM Joint Symposium, Sendai, Japan. Paper JD-2-1, 105–120.
- Parkhurst, D. L., and Appelo, C. A. J.: 1999, ‘User's guide to PHREEQC (Version2) - A computer program for speciation, reaction-path, advective-transport, and inverse geochemical calculations’, USGS Water-Resources Investigations Report 99-4259.
- Robins, R. G.: 1981, ‘The solubility of metal arsenates’, Metallurgical Transactions 12B, 103–109.
- Robins, R. G.: 1985, ‘The solubility of barium arsenates: Sherritt's barium arsenate process’, Metallurgical Transactions 16B, 404–406.
- Smedley, P. L., and Kinniburg, D. G.: 2002, ‘A review of the source, behaviour and distribution of arsenic in natural waters’, Appl. Geochem. 17, 517–568.
- Stefanakis M. and Kontopoulos A.: 1988, ‘Production of environmentally acceptable arsenites-arsenates from solid arsenic trioxide’, In R. G. Reddy, J. L. Hendrix and P. B. Queneau (eds), Arsenic Metallurgy Fundamentals and Applications, The Minerals, Metals and Materials Society, Warrendale, PA, U.S.A., pp. 287–304.
- Swash, P. M. and Monhemius, A. J.: 1995, ‘Synthesis, characterisation and solubility testing of solids in the Ca-Fe-AsO4 system’, Paper presented at Sudbury'95, Conference on Mining and the Environment, Sudbury, Ontario, 28 May – 1 June.
- US EPA: 1998, ‘Locating and estimating air emissions from sources of arsenic and arsenic compounds’, EPA-454-R98-013, Office of Air Quality Planning and Standards. Valenzuela, A.: 2000, ‘Arsenic management in the metallurgical industry’, M. Sc. Thesis, University of Laval, Department of mines and metallurgy, Quebec, Canada./Sc.
- Solubility and Stability of Calcium Arsenates at 25∘C
Water, Air, and Soil Pollution
Volume 169, Issue 1-4 , pp 221-238
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers
- Additional Links
- calcium arsenates
- free energies of forming
- solubility products
- Industry Sectors