Kinetics of extraction of Ti(IV) from SO42– medium by Cyanex 301 dissolved in kerosene containing 5% heptan-1-ol

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Abstract
The kinetics of Ti(IV) extraction by Cyanex 301 (HA) were investigated by measuring initial flux of Ti(IV) transfer (F, kmol/m2s), using a Lewis cell, operated at 3 Hz. The empirical flux equation at 298 K is found to be as follows: F (kmol/m2s) = 10–4.288 [Ti(IV)] (1 + 447 [H+])–1 [HA](o) (1 + 1.18[SO42–])–1. The activation energy, Ea, has been measured to be within 37–60 kJ/mol, depending on experimental parameters and temperature region. The ΔS± value is always highly negative. Analysis of the flux equation has been done, given various parametric conditions, to elucidate the mechanism of extraction. The rate-determining chemical reaction step, in most parametric conditions, appears to be as follows: TiO2+ + A– → TiOA+; and this step occurs via an SN2 mechanism as suggested by high negative ΔS± values. However, in certain cases, the extraction process appears as intermediate controlled as supported by Ea value of less than ~48 kJ/mol.

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