Abstract: he photocatalytic degradation of reactive brilliant red X-3B was investigated in an internal loop airlift photocatalytic reactor. The effects of initial substrate concentration, catalyst load, initial solution pH, aeration amount, temperature, and UV intensity on the photocatalytic degradation reaction were systematically analyzed. The results showed that the degradation rate of active brilliant red X-3B could reach more than 85% under the conditions of a pH of 4-10, a catalyst dosage of 0.5 g/L ,an air flowrate of 2.5 m³/h, an active brilliant red X-3B concentration of 50 mg/L for 3 h of photocatalytic reaction. The results of the reaction kinetic studies indicate that the degradation of reactive brilliant X-3B by photocatalytic treatment can be described by the Langmuir-Hinshelwood model. An empirical model was established to predict the photocatalytic degradation performance of active brilliant X-3B with the variables of reaction time, substrate concentration, UV light intensity and aeration amount. The coefficient of determination between the predicted and experimental value was 0.958, which can provide theoretical guidance and experience for the following amplification experiments.

Key words: internal loop airlift reactor, photocatalytic, reactive brilliant red X-3B, degradation