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The titled system has been investigated from the modelling point of view. The equilibration time for the system is 45 min, and 5% (v/v) heptane-1-ol in the organic phase is used as a de-emulsifier. The factors affecting the extent of extractions are [Ti(IV)], pH(eq), [Cyanex 301], [SO42-] and temperature (T). The selected levels are high (+) and low (-) for these factors in the present investigation. Model equation for the extraction of Ti(IV) by Cyanex 301 is determined from 25 full factorial design. However, the success of the factorial design depends on the linear relationship between yield and factor. Plots of log CD vs log [Ti(IV)], pH(eq), log [Cyanex 301] and log [SO42-] are curves. Logistic functions involving these factors are considered in designing. While [Ti(IV)] < 1.00 g/L and [HA](o) > 0.10 mol/L, considered logistic functions viz. -log(1+316.2 ([Ti(IV)], mol/L)), -log (10-pH + 229 10-2pH), log ([HA](o), mol/L), -log (1+0.79 ([SO42-], mol/L)) and absolute temperature are abbreviated as M, P, E, S and T, respectively. Model is log CD = 5.847 + 0.964 M + 0.909 P + 2 E + 0.995 S - (1437.5/T). The experimental model illustrates that there is no interaction effect between the factors under investigation. [ABSTRACT FROM AUTHOR]

The titled system has been investigated using a single drop technique and flux (F) method of data treatment. In calculating fluxes, the time for drop formation and coalescence (Δt = 0.75 s) is considered. At lower concentration region of vanadium, V(V), the rate of V(V) transfer is directly proportional to its concentration. With the increase in [V(V)], slowly extractable V(V) species are formed gradually resulting in decrease in rate. Rate is directly proportional to the square root of [TOA]. It is reported that the most favorable extractable V(V) species exists in maximum amount at pH 2, and so, log F vs pH plots show a maximum at pH~2. The flux of V(V) transfer in most cases is found to be decreased with increasing [NO3-]. Reaction orders with respect to [V(V)], pH and [NO3-] have been attempted to be estimated, but in vein due to non-linearity of plots in most cases. Activation energies for the present system is ~-12 kJ/mol. This is unexpected but explained. Due to irregular variation of the composition of extractable species with [V(V)], [H+]; as well as temperature; it is not possible to elucidate the value of rate constant (k) and mechanism in simple way. [ABSTRACT FROM AUTHOR]

The title system has been studied elaborately. 3% (v/v) octan-1-ol is added as de-emulsifier. Equilibration time is < 2 min. Distribution ratio (D) at constant pH(eq) and [H2A2] is independent of [Ni(II)](aq). The pH dependency is always found to be 2; whilst the extractant dependence is found to vary from 1 (at lower concentration region, lcr) to 3 (at high concentration region, hcr). Moreover, the distribution ratio is found to be inversely proportional to (1+6.92 […]) and [Ac-]. Based on these results, the extraction equilibrium reactions have been proposed at various parametric conditions. The extraction process is endothermic (ΔH = 54.66 kJ/mol). The Kex values at 303 K are evaluated to be 10-11.086 and 10-11.56 at lcr and hcr of extractant, respectively. The maximum loading capacity is 21.28 g Ni(II) per 100 g extractant indicating the formation of NiAcA at maximum loading. The stripping ability of various inorganic acids towards loaded nickel, as well as, the possibilities of separation of Ni(II) from its binary mixtures with other ions of 3d-block elements have also been investigated [ABSTRACT FROM AUTHOR]

The title system has been investigated over a wide range of aqueous acidity. The equilibration time is 1 h. The extraction ratio (D) is independent of [Fe(III)] provided equilibrium [HCl] and [HA] are kept constant. At a constant equilibrium extractant concentration, the [HCl] dependences are -1.6, ~0 and -3 in the [HCl] regions of >3, 2-0.5 and <;0.3 M; respectively; whilst at constant [HCl], the [HA] dependence is 3.0. On the other hand, [Cl-] dependence varies within -0.5 to -3 at constant [HCl] of 0.3 M; whereas its values are ~ -1 and ~ 0.63 at constant [HCl] of 3 and 1 M, respectively. Based on these results the extraction mechanisms have been suggested to be FeCln(3-n) + 3 HA(o) ⇌ FeA3(o) + n Cl- + 3 H+ in the low [HCl] region, FeCl(3-n)n+ + 3 HA(o) + n Cl- ⇌ FeCl3.3HA(o) in the intermediate [HCl] region and HFeCl4 + 3 HA(o) ⇌ FeCl3.3HA(o) + HCl in the high [HCl] region under investigation. The Kex and ΔH values have been evaluated. Loading capacity is 5.5 g Fe(III)/100 g Cyanex 301. The stripping can be made effective by a mixture of 6 M H2SO4 and 1 M Na2C2O4. [ABSTRACT FROM AUTHOR]