TY - JOUR
T1 - Optimisation of degradation conditions of 1,8-Diazabicyclo [5.4.0]undec-7-ene in Water and Reaction Kinetics Analysis Using a Cocurrent Downflow Contactor Photocatlytic Reactor
AU - Ochuma, IJ
AU - Fishwick, Robert
AU - Wood, Joseph
AU - Winterbottom, John
PY - 2007/5/11
Y1 - 2007/5/11
N2 - The photocatalytic degradation of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, a non-biodegradable nitrogenous organic compound) in water was optimised under UV radiation using titanium dioxide photocatalyst. The reactor used was a pilot scale cocurrent downflow contactor photocatalytic reactor (CDCPR), a system offering very high mass transfer efficiency. The effect of photocatalyst loading, initial substrate concentration, temperature, pH, and different combinations of UV, O-2, H2O2 and TiO2 on the photocatalytic oxidation of DBU was investigated. The TiO2 photocatalyst used was Degussa VPAeroperl P25/20, a granulated form of Degussa P-25, recently developed to ameliorate downstream catalyst separation problems. The CDCPR was fitted with an internally and vertically mounted 1.0 kW UV lamp. The reactions were carried out at 40-60 degrees C and 1 barg, with the reactor being operated in closed loop recycle mode and suspended photocatalyst being re-circulated. Optimisation of reaction conditions using a combination of TiO2, UV radiation and 02 gave the most rapid degradation and mineralisation of the DBU in comparison with other processes. Under optimised conditions, 100% degradation of DBU was achieved in 45 min, with a quantum yield of 7.39, using a 1 kW lamp, 0.5 g/dm(3) TiO2, 100 mg/dm(3) DBU, 1 barg, 50 degrees C and pH of 3.17. Investigating the reaction pathway and its modelling showed a first order dependency, incorporating the effect of first intermediates of degradation. The activation energy was found to be 54.68 kJ mol(-1) showing a significant influence of temperature on the photocatalytic degradation of DBU. (c) 2007 Elsevier B.V. All rights reserved.
AB - The photocatalytic degradation of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, a non-biodegradable nitrogenous organic compound) in water was optimised under UV radiation using titanium dioxide photocatalyst. The reactor used was a pilot scale cocurrent downflow contactor photocatalytic reactor (CDCPR), a system offering very high mass transfer efficiency. The effect of photocatalyst loading, initial substrate concentration, temperature, pH, and different combinations of UV, O-2, H2O2 and TiO2 on the photocatalytic oxidation of DBU was investigated. The TiO2 photocatalyst used was Degussa VPAeroperl P25/20, a granulated form of Degussa P-25, recently developed to ameliorate downstream catalyst separation problems. The CDCPR was fitted with an internally and vertically mounted 1.0 kW UV lamp. The reactions were carried out at 40-60 degrees C and 1 barg, with the reactor being operated in closed loop recycle mode and suspended photocatalyst being re-circulated. Optimisation of reaction conditions using a combination of TiO2, UV radiation and 02 gave the most rapid degradation and mineralisation of the DBU in comparison with other processes. Under optimised conditions, 100% degradation of DBU was achieved in 45 min, with a quantum yield of 7.39, using a 1 kW lamp, 0.5 g/dm(3) TiO2, 100 mg/dm(3) DBU, 1 barg, 50 degrees C and pH of 3.17. Investigating the reaction pathway and its modelling showed a first order dependency, incorporating the effect of first intermediates of degradation. The activation energy was found to be 54.68 kJ mol(-1) showing a significant influence of temperature on the photocatalytic degradation of DBU. (c) 2007 Elsevier B.V. All rights reserved.
KW - environment
KW - cocurrent downflow contactor
KW - photocatalysis
KW - kinetics
KW - optimisation
U2 - 10.1016/j.apcatb.2006.12.008
DO - 10.1016/j.apcatb.2006.12.008
M3 - Article
SN - 0926-3373
VL - 73
SP - 259
EP - 268
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
IS - 3-4
ER -