Solvent extraction of Ti(IV) in the Ti(IV)–SO42 − (H+, Na+)–Cyanex 302–kerosene–5% (v/v) hexan-1-ol system

The equilibrium of extraction of Ti(IV) in the Ti(IV)–SO42 − (H+, Na+)–Cyanex 302 (H2A2)–kerosene–5% (v/v) hexan-1-ol system has been studied. Hexan-1-ol is a de-emulsifier. The equilibration time is < 20 min. The extraction ratio (CD) at a constant equilibrium pH(eq) and [H2A2] is inversely proportional to (1 + 141.3 [Ti(IV)]), (10− pH + 58.88 × 10− 2pH) and (1 + 1.86 [SO42 −]) but is directly proportional to [H2A2](o)1. 5. Hexan-1-ol has an adverse effect on extraction. The equilibrium constant (Kex) is measured to be 100.424 at 303 K for extraction of TiO.OH+. The enthalpy change is ~ 50 kJ/mol. Extraction reactions have been proposed at different experimental conditions. The loading capacity is 5.08 g Ti(IV)/100 g Cyanex 302. As diluent, n-C7H16, C6H6, 1,2-C2H4Cl2, CCl4 and C6H12 are better than kerosene. The novelty of this process is that the stripping can be done effectively by 1 mol/L H2SO4 solution alone. Possibilities of separation of Ti(IV) from some 3d-block metal ions have been predicted.Considering five logistic functions of factors ([ ] in mol/L), viz. M = log (1 + 141.3[Ti(IV)]), P = − log (10− pH + 58.88 × 10− 2pH), E = log [Cyanex 302], S = log (1 + 1.86[SO42 −]), and T = absolute temperature at two levels of high and low values, the factorial design yields the model: log CD = 15.824 − 1.027 M − 0.956 P + 1.481 E − 1.075 S − 4654.43/T. In this model, the constant represents the log Kex value at infinite high temperature. The equation permits to calculate log Kex value at any temperature (= 0.463 at 303 K which is very close to 0.424 obtained from the equilibrium study). The model can describe the system efficiently.

► Extraction of Ti(IV) by Cyanex 302 is reported, which is not reported earlier.
► Novelty of the process is easy stripping of extracted complex by mineral acids.
► Equation for extraction equilibrium constant has been established.
► The system has been modeled by five factor two level factorial design.