INTERFACIAL ACTIVITY OF BIS(2-ETHYLHEXYL) PHOSPHORIC-ACID IN MODEL LIQUID-LIQUID-EXTRACTION SYSTEMS

The interfacial activity of bis(2-ethylhexyl)phosphoric acid (HDEHP) h as been studied at different alkane/0.1 M HCl interfaces. The experime ntal parameters investigated include the molecular weight of the alkan e used as a diluent, temperature, and the nature and content of long c hain alcohols often used as modifiers for third-phase elimination, The molecular weight of the alkanes was found to have a significant effec t upon the surface excess (Gamma(HDEHP)(max)) of HDEHP at the saturate d interface: Gamma(HDEHP)(max) increases as molecular weight is increa sed. However, the effect of temperature is very weak, Finally, it is s hown that there is strong competition between HDEHP and long chain alc ohols such as isodecanol and 1-octanol for adsorption at the interface . The modelling of the interfacial tension isotherms is discussed.