The tetracycline degradation in a photocatalytic fuel cell microreactor using a ZnO nanorod/Bi2MoO6/ZIF-67 photocatalyst responsive to visible light

In the Photocatalytic fuel cell microreactor system, a three-component photocatalyst powder of ZnO nanorod/Bi2MoO6/ZIF-67 was synthesized and deposited as a photoanode immobilize on an FTO substrate using the drop-casting method. The electrochemical properties and photocurrent obtained in the ZnO/Bi2MoO6/ZIF-67 photoanode/FTO system exceeded those of ZnO/Bi2MoO6/FTO and ZnO/FTO. The use of the ZnO/Bi2MoO6/ZIF-67 composite on the FTO substrate led to a reduction in the bandgap energy from 1.74 ev to 1.61 ev. The optimal conditions for tetracycline degradation included a tetracycline concentration of 20 ppm, a pH of 7, light intensity of 7.9 mW/cm2, and a flow rate of 120 µL/min. Under these conditions, the removal efficiency and TOC were calculated as 97.16 % and 92.4 %, respectively. The maximum power density was 35.1 mW/cm2, and the photocurrent density was 1.4 mA/cm2. The kinetics of tetracycline removal in the microreactor input followed the Langmuir-Hinshelwood model, and mass transfer resistance in the fluid phase did not significantly affect the reaction kinetics. Additionally, the time-on-stream (TOS) curve indicated that the removal efficiency dropped below 80 % after 1450 min of operation, reaching a breaking point.