Equilibrium of the Extraction of V(IV) in the V(IV)-SO<sub>4</sub><sup>2-</sup>(H<sup>+</sup>, Na<sup>+</sup>)—Cyanex 302-Kerosene System

• 作者: Aneek Krishna Karmakar Ranjit Kumar Biswas
• 来源期刊: 有色冶金(英文)
• 学科: 化学
• 关键词: EXTRACTION EQUILIBRIUM Vanadium(IV) CYANEX 302 KEROSENE Sulphate
• 年，卷（期）: 2012,（3）
• 页码范围: 23-31
• 页数: 9页
• 分类号: O6

摘要

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;and [SO42-]0 and [SO42-]-1 in the lower [SO42-] (42-] (>1 mol/L) regions, respectively. The apparent extraction equilibrium constant (Kex) in 0.02 mol/L SO42- medium and at 303 K is found to vary from 10-3.447 to 101.508 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.