Photocatalyzed oxidation of phenol in water using a cocurrent downflow contactor reactor (CDCR)

The oxidation of aqueous solutions of phenol as a typical model pollutant has been carried out in the presence of an ultra-violet (UV) irradiated TiO2 catalyst in a CDC reactor. The CDCR was fitted with internally mounted 30 W and 1.0 kW W lamps. The reactions were carried out at 40-50 degrees C and 202.6 kPa, with the reactor being operated in closed loop recycle mode and suspended catalyst being recirculated, The CDCR is a device of high mass transfer efficiency, giving unusually large gas hold-up (approximately 50%). The CDCR was operated (i) with oxygen mass transfer and dissolution in the zone above the UV source and (ii) with oxy gen dispersion and mass transfer occurring along and around the lamp housing. Using the higher powered lamp, 100% conversion of phenol was obtained from solutions containing 100 mg/dm(3). Under specific conditions the presence of TiO2 catalysts was observed to give the most rapid oxidation degradation of the phenol.