초록
<P><B>Abstract</B></P><P>The direct reactive extraction of propionic acid from <I>Propionibacterium acidipropionici</I> broths with solutions of tri‐<I>n</I>‐octylamine in dichloromethane, <I>n</I>‐butyl acetate or <I>n</I>‐heptane underlined the strong negative influence of the cells, due to the blockage of the interface by their adsorption. The magnitude of this effect <#>depends on the affinity of the cells for the organic phase, which is more important for <I>n</I>‐heptane, but only at biomass concentrations below 18 g L<SUP>–1</SUP> d.w. (dry weight). Moreover, the interfacial mass transfer of the acid is also controlled by the solvent polarity, and is accelerated from <I>n</I>‐heptane to dichloromethane and by the addition to the organic phase of 1‐octanol as a phase modifier. The influences of the biomass concentration, the rotation speed and the solvent dielectric constant were included in a mathematical model describing the solute mass flow from the aqueous to the organic phase.</P>