Equilibrium of the Extraction of V(IV) in the V(IV)-SO₄^2-(H⁺, Na⁺)—Cyanex 302-Kerosene System

Ranjit Kumar Biswas, Aneek Krishna Karmakar

Department of Applied Chemistry & Chemical Engineering, Rajshahi University, Rajshahi, Bangladesh.

DOI: 10.4236/ijnm.2012.13004                

Abstract

The title system has been investigated from the equilibrium point of view. Significant extraction occurs above pH 2. Equilibration time is 20 min. The extraction ratio (D) remains constant with increasing [V(IV)] of at least 0.50 g/L. It is inversely proportional to [H⁺]², [H⁺] and [H⁺]^0.3 in the lower pH (<2.25), medium pH (~2.90) and higher pH (~4.0) regions, respectively. Moreover, it is proportional to [Cyanex 302]²; and [SO₄^2-]⁰ and [SO₄^2-]^-1 in the lower [SO₄^2-] (<0.05 mol/L) and higher [SO₄^2-] (>1 mol/L) regions, respectively. The apparent extraction equilibrium constant (K_ex) in 0.02 mol/L SO₄^2- medium and at 303 K is found to vary from 10^-3.447 to 10^1.508 with increasing equilibrium pH from 2.25 to 4.00. Various sulphated, hydrolyzed, hydrated and mixed sulphated hydrolyzed species of V(IV) have been considered at different extraction conditions to propose the extraction equilibrium reactions to form always [VO(HA₂)₂] as the extractable species. The system is highly temperature dependent with ?H value of ~90 kJ/mol and ~25 kJ/mol in lower and higher temperature regions, respectively. The calculated loading capacity is low (4.05 g V(IV)/100 g Cyanex 302). Kerosene is a better diluent over CHCl₃, Cyclo-C₆H₁₂ and CCl₄; but much better solvents are C₆H₆, C₆H₅CH₃, n-C₇H₁₆,C₆H₄(CH₃)₂, petroleum benzin, 1,2-C₂H₄Cl₂, C₆H₅Cl. Mineral acids (1 mol/L) are able to strip off V(IV) from the organic phase in a single-stage. Using Cyanex 302, almost complete separations of V(IV) from Cu(II) at pH 1.0 and from Ni(II) at pH_(eq) 4.5 are possible in a single-stage of extraction; whereas, its separation from Zn(II) at pH_(eq) 2.5, Co(II) at pH_(eq) 3.5, Fe(III) at pH_(eq) 2.0 and Ti(IV) at pH_(eq) 2.5 will require counter-current multi-stage extractions.

Keywords

Extraction Equilibrium; Vanadium(IV); Cyanex 302; Kerosene; Sulphate

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	T. Sekine and Y. Hasegawa, “Solvent Extraction Chemistry: Fundamentals and Applications,” Marcel Dekker, Inc., New York, 1977, pp. 564-567.
[2]	F. Islam and R. K. Biswas, “The Solvent Extraction of Vanadium(IV) with HDEHP in Benzene and Kerosene: The Solvent Extraction of Vanadium(IV) from Sulphuric Acid Solution with Bis-(2-ehylhexyl) Phosphoric Acid in Benzene and Kerosene,” Journal of Inorganic and Nuclear Chemistry, Vol. 42, No. 3, 1980, pp. 415-420. doi:10.1016/0022-1902(80)80018-2
[3]	F. Islam and R. K. Biswas, “Kinetics of Solvent Extraction of Metal Ions with HDEHP-II: Kinetics and Mechanism of Solvent Extraction of V(IV) from Acidic Aqueous Solutions with Bis-(2-ethylhexyl)phosphoric Acid in Benzene,” Journal of Inorganic and Nuclear Chemistry, Vol. 42, No. 3, 1980, pp. 421-429. doi:10.1016/0022-1902(80)80019-4
[4]	T. Sato, T. Nakamura and M. Kawamura, “The Extraction of Vanadium(IV) from Hydrochloric Acid Solutions by Di-(2-ethylhexyl)-phosphoric Acid,” Journal of Inorganic and Nuclear Chemistry, Vol. 40, No. 5, 1978, pp. 853- 856. doi:10.1016/0022-1902(78)80164-X
[5]	J. P. Brunette, F. Rastegar and M. J. F. Leroy, “Solvent Extraction of Vanadium(V) by Di-(2-ethylhexyl)-phosphoric Acid from Nitric Acid Solutions,” Journal of Inorganic and Nuclear Chemistry, Vol. 41, No. 5, 1979, pp. 735-737. doi:10.1016/0022-1902(79)80364-4
[6]	M. A. Hughes and R. K. Biswas, “The Kinetics of Vanadium(IV) Extraction in the Acidic Sulphate-D2EHPA-n-heptane System Using the Rotating Diffusion Cell Technique,” Hydrometallurgy, Vol. 26, No. 3, 1991, pp. 281- 297. doi:10.1016/0304-386X(91)90005-7
[7]	R. S. Juang and R. H. Lo, “Stoichiometry of Vanadium(IV) Extraction from Sulfate Solutions with Di(2- Ethylhexyl) Phosphoric Acid Dissolved in Kerosene,” Journal of Chemical Engineering of Japan, Vol. 26, 1993, pp. 219-222. doi:10.1252/jcej.26.219
[8]	R. K. Biswas and M. G. K. Mondal, “Kinetics of VO2+ Extraction by D2EHPA,” Hydrometallurgy, Vol. 69, No. 1-3, 2003, pp. 117-133. doi:10.1016/S0304-386X(02)00208-6
[9]	J. Saji and M. L. P. Reddy, “Solvent Extraction Separation of Vanadium(V) from Multivalent Metal Chloride Solution Using 2-Ethylhexyl Phosphonic Acid Mono-2- Ethylhexyl Ester,” Journal of Chemical Technology and Biotechnology, Vol. 77, No. 10, 2002, pp. 1149-1156. doi:10.1002/jctb.690
[10]	J. Saji and M. L. P. Reddy, “Selective Extraction and Separation of Titanium(IV) from Multivalent Metal Chloride Solutions Using 2-Ethylhexyl Phosphonic Acid Mono 2-Ethylhexyl Ester,” Separation Science and Technology, Vol. 38, No. 2, 2003, pp. 427-441. doi:10.1081/SS-120016583
[11]	J. Saji, J. K. Saji and M. L. P. Reddy, “Liquid-Liquid Extraction of Tetravalent Titanium from Acidic Chloride Solutions by Bis(2,4,4-trimethylpentyl)phosphinic acid,” Solvent Extraction and Ion Exchange, Vol. 18, No. 5, 2000, pp. 877-894. doi:10.1080/07366290008934712
[12]	M. Ulewicz and W. Walkowiak, “Selective Removal of Transition Metal Ions in Transport through Polymer Inclusion Membranes with Organophosphorus Acid,” Environment Protection Engineering, Vol. 31, No. 3-4, 2005, pp. 74-81.
[13]	W. A. Rickelton, “Novel Uses for Thiophosphinic Acids in Solvent Extraction,” Journal of Metals, Vol. 44, No. 5, 1992, pp. 52-54.
[14]	A. Saily and S. N. Tandon, “Liquid-Liquid Extraction Behavior of V(IV) Using Phosphinic Acids as Extractants,” Fresenius’ Journal of Analytical Chemistry, Vol. 360, No. 2, 1998, pp. 266-270.
[15]	P. Zhang, K. Inoue and H. Tsuyama, “Recovery of Molybdenum and Vanadium from Spent Hydrodesulfurization Catalysts by Means of Liquid-Liquid Extraction,” Kagaku KogakuRonbunshu, Vol. 21, 1995, pp. 451-456. doi:10.1252/kakoronbunshu.21.451
[16]	P. Zhang, K. Inoue, K. Yoshizuka and H. Tsuyama, “Solvent Extraction of Vanadium(IV) from Sulfuric Acid Solution by Bis(2,4,4-trimethylpentyl) Phosphinic Acid in Exxsol D80,” Journal of Chemical Engineering of Japan, Vol. 29, No. 1, 1996, pp. 82-87. doi:10.1252/jcej.29.82
[17]	K. C. Sole and J. B. Hiskey, “Solvent Extraction Characteristics of Thio Substituted Organophosphinic Acid Extractants,” Hydrometallurgy, Vol. 30, No. 1-3, 1992, pp. 345-365. doi:10.1016/0304-386X(92)90093-F
[18]	J. Bassett, R. C. Denney, G. H. Jeffery and J. Mendham, “Vogel’s Textbook of Quantitative Inorganic Analysis Including Elementary Instrumental Analysis,” 4th Edition, ELBS and Longman, London, 1979, pp. 752-753.
[19]	M. R. Ali, R. K. Biswas, S. M. A. Salam, A. Akhter, A. K. Karmakar and M. H. Ullah, “Cyanex 302: An Extractant for Fe3+ from Chloride Medium,” Bangladesh Journal of Scientific and Industrial Research, Vol. 46, No. 4, 2011, pp. 407-414.
[20]	E. Paatero, T. Lantto and P. Ernola, “The Effect of Trioctylphosphine Oxide on Phase and Extraction Equilibria in Systems Containing Bis(2,4,4-trimethylpentyl) Phosphinic Acid,” Solvent Extraction and Ion Exchange, Vol. 8, No. 3, 1990, pp. 371-388.
[21]	doi:10.1080/07366299008918006 R. M. Smith and A. E. Martell, “Critical Stability Constant,” In: Inorganic Complexes, Plenum Press, New York, 1976.