Estimation of Trioctylphosphine Oxide (TOPO) Diffusion Coefficients by Dynamic Adsorption Measurements in Model Extraction Systems

Adsorption at the liquid/liquid interface in mixed systems with hydrophobic extractants and modifiers

“…The data presented in Table 1 show that the values of the diffusion coefficient of HNAF, β-diketone and their mixture tend to decrease as the concentration is increased. Similar relations between the values of diffusion coefficient and the bulk surfactant concentration have also been observed once by other authors for non-ionic surfactants in the hydrocarbon/water systems [1,[10][11][12][13][14][15][16] and air/water [17][18][19]. The lower values of diffusion coefficients for higher concentration could be explained by increase of aggregates concentration in more concentrated solutions due to the association process [20].…”

Unexpected inverse correlations and cooperativity in ion-pair phase transfer

“…This is consistent with prior dynamic interfacial tension measurements of phosphine oxide surfactants like trioctylphosphine oxide (TOPO) that also indicate decreased surface activity with increased aqueous ionic strength. 61 At the 50% v/v TBP conditions, going from 1 M to 5 M [LiNO 3 ] decreases the TBP coverage from ∼ 0.03 to ∼ 0.01 TBP/Å 2 or by 60%. The distribution of the adsorbed TBP (projected into the xy plane) is graphically illustrated in (Figure 2).…”

Reversed micelle formation in a model liquid–liquid extraction system

“…The same effect was found in the case of trioctylphosphine oxide (TOPO) at the hydrocarbon/HNO 3 interface [38]. The Cyanex923 extractant molecule contains strong polar -P=O functional groups of high nucleophilicity.…”