Solvent Extraction of Ti(IV) and V(IV) by Cyanex 301 and Cyanex 302 and Application of Yates Experimental Design

Abstract

The solvent extractions in (i) Ti(IV)-Cyanex 301 {HA), (ii) Ti{IY)-Cyanex 302 (H2A2), (iii) V(IV)-HA and (iv) V(IV) - H2A2 have been investigated from equilibrium and kinetic points of view. Yates Experimental Design has been made to the equilibrium and kinetic data for all systems. In system (i) and (ii), heptanol and hexanol (respectively) have been used as de-emulsifier. The equilibration times are 40, 30, 15 and 20 min, respectively. The extraction equilibria at 303 K can be expressed (respectively) as: Kcx = 101.1 17 = co (1+316.2 [Ti(IV)]) {I+ 0.794 [SO/] ([H+] + 229 [W]2) / [HA)to) K.x = 10°.339 = cD (I+ 141.3 [Ti(JV)]) (I+ 1.86 [SO/°]) ([H+)+58.88 [H+J2) I [H2A2Jtii1 K.x = 10·t.42 = cD [H+J2 / [HA)fo) (1+1.58 [SO/]) Kcx = cD [H+r (I +2.24 [SO/·]) / [H2 A2 lfo) [Kcx depends on 'x' and 'x' varies between 2 - OJ The processes are endothermic with 􀂨H values of -27, -50, -16 and -25 kJ/mol (at l.t.r and - 90 kJ/mol at h.t.r), respevtively. The loading capacities are 7.11, 5.08, 7.87 and 4.05 g/L respective metal ions/ 100 g respective extractant. Suitable diluents are chlorobenzene, n-heptane, kerosene and toluene (benzene) respectively, for systems (i), (ii), (iii) and (iv). The cited equilibrium expressions have been used to suggest equilibrium reactions. The extracted species are [TiOA2], [TiOA2.HA], [VOA2] and [VO(HA2)2] in respective systems; but the reacting metallic species depends on the aqueous pH and sulphate ion concentration ranges. The kinetics of forward extraction of the systems (i), (ii), (iii) and (iv) have been investigated by measuring initial flux of metal ion transfer in a Lewis cell operated at 3 Hz………………………………………