Hydrodynamic and mass transfer coefficient in a split-cylinder airlift reactor for four different oil-in-water micro-emulsions containing kerosene, heavy naphtha, light naphtha, and diesel as oil-based with concentrations of 3%, 5%, and 7 % (v/v) were considered. The experimental results showed that with increasing the oil in water ratio, the gas holdup increased but liquid circulation velocity and oxygen transfer coefficient decreased. Light naphtha with the lowest surface tension and viscosity had the maximum mass transfer and gas holdup, and the minimum liquid circulation velocity, while diesel with the highest surface tension and viscosity had the minimum mass transfer and gas holdup and the maximum liquid circulation velocity.
