The transfer of alkanoic acids from dodecane to water

A rotating diffusion cell was used to study the transfer of five alkanoic acids from dodecane to water under conditions of known interfacial area and hydrodynamics. The acids studied were acetic, butanoic, hexanoic, 2-methylbutanoic and 2,2-dimethyl-propanoic acids. Small interfacial resistances to mass transfer were noted, the mass transfer coefficients for interfacial transfer being in the range 2.6 to 4.7 μm/s at 25 °C. This small range means that the effects of the length and structure of the alkane chain on the resistance to mass transfer are minimal. A study of the temperature dependence of the resistance to mass transfer at the interface showed that the resistance is largely entropic rather than enthalpic.