(70d) Mass Transfer Characteristics of an Airlift Contactor with a Semipermeable Membrane, Containing Aqueous Hydrocarbon Solution

The effect of hydrocarbon contaminants on gas-liquid mass transfer coefficient, KLa, was studied in a 25 L concentric cylindrical airlift contactor with a semipermeable membrane. A specific form of the continuity equation was combined with gas holdup values in order to derive an expression for calculating the experimental mass transfer coefficient. A new surface renewal-stretch model was developed to correlate experimental data for the time-average overall mass transfer coefficient, KL,av, in the airlift contactor. This model was modified in order to predict the effect of hydrocarbon dissolution on mass transfer coefficient. Water with different hydrocarbon concentrations of 0-35 mg/L p-Xylene and 0-6 mg/L naphthalene was used as liquid media, under varying solid loadings and superficial gas velocities. The results indicated that deviation of mass transfer coefficient could go either way when hydrocarbons were present in water: p-Xylene tends to increase mass transfer coefficient, while naphthalene, which has some surfactant properties, reduces it.