Oxygen transfer in three-phase airlift and stirred tank reactors using silicone oil as transfer vector

The use of organic liquids as vectors to enhance mass transfer has been applied since the 1970s. However, mass transfer in three-phase reactors is only partially understood. This paper aimed to characterize oxygen transfer in three-phase reactors containing air as gas, silicone oil as vector and water as aqueous phase. A mass transfer model that considers separately air/vector, vector/water and air/water oxygen transfers was developed. The model was used to describe oxygen transfer in airlift and stirred tank reactors containing from 0 to 50% of silicone oil. Under the experimental conditions, silicone oil had a positive effect on the overall oxygen transfer. In both reactor designs, the maximum overall oxygen transfer was observed with 10% silicone oil which was increased by 65 and 84% in the airlift and stirred reactor, respectively, compared to reactors operated without silicone oil. The overall transfer increase was mainly due to an enhanced air/water transfer. With 10% silicone oil, the air/water contribution to the overall oxygen transfer was 94.7 and 93.0% for the airlift and stirred reactor, respectively.