Carbon Dioxide Absorption into Stirred Emulsions of n-Alkanes

Volumetric mass transfer coefficients k(L)a for CO2 absorption into n-alkane/water emulsions were determined at oil volume fractions of 0-100 % in a stirred tank at a stirring speed of 1000 min(-1). The oil was n-heptane, n-hexadecane, or n-dodecane. The decrease of k(L)a with increasing volume fraction of dispersed oil can be uniformly correlated to the emulsion viscosity with the power of -0.72. Only the addition of n-heptane caused a strong increase of the mass transfer coefficient. Upon addition of the surfactant sodium dodecyl sulfate to n-heptane emulsions, k(L)a decreased as for the other oils. The increase can therefore be attributed to the spreading of n-heptane on the bubble surface enabling gas-oil contact, whereas spreading is inhibited by the ionic surfactant.