Pilot- plant study for the photocatalytic/electrochemical degradation of Rhodamine B

The combined photocatalytic/electrochemical breakdown performance of Rhodamine B dye in DI water and Na-based electrolytes was investigated in a 10 L semi-pilot flow reactor fitted with a Pd-doped TiO2/Ti anode and a photocatalytic TiO2 ceramized fabric sleeve. The combined photocatalytic/electrochemical degradation performance was evaluated in Na2CO3, (Na2CO3 + NaCl), NaHCO3, and Na2SO4 supporting electrolytes, and compared with that obtained by the electrochemical and photocatalytic processes alone. It was found that electrolytes containing CO32- and HCO3- ions impair the photocatalytic performance of the TiO2 ceramized fabric, whereas the Na2SO4 supporting electrolyte does not, thus allowing a synergetic action of the electrochemical and photocatalytic Rhodamine B degradation processes. Over three hours, 80% degradation efficiency was obtained in a NaHCO3 supporting electrolyte, while nearly 100% degradation efficiency was obtained in a Na2SO4 supporting electrolyte. Under the electrochemical regime of this work (5 VDC cell potential and 3.2 A cell current), Rhodamine B degradation was exceedingly fast (similar to 100% in 1 h) in NaCl-containing electrolyte owing to electrochemical chlorination of the solution. Kinetics and process-related costs are also briefly discussed.