Synthesis and immobilization of HC/BiVO4 catalyst particles with PTFE for photocatalytic tetracycline degradation: Preparation, performance and mechanism

The hydrothermal carbon/bismuth vanadate (HC/BiVO4) composite catalyst particles were prepared by one-step hydrothermal process. For effective and convenient photocatalytic organics degradation, the sandwich-like immobilization of HC/BiVO4 particles was performed utilizing polytetrafluoroethylene (PTFE) as an adhesive agent, NaCl as a pore-creating agent and PTFE/graphite composite as the interlayer. The obtained results indicated that HC/BiVO4 exhibited the higher performance than the pure BiVO4 towards photocatalytic tetra-cycline degradation owing to its enhanced separation of electron-hole (e(-)-h(+)) pairs as well as relatively higher electron transfer ability. Four active species including superoxide anion radical (O-center dot(2)-), h+, hydroxyl radical ((OH)-O-center dot) and singlet oxygen (O-1(2)) could be identified from the developed photocatalytic system, whereas O-center dot(2)- played the predominant role in tetracycline degradation. It was found that the immobilized photocatalyst owned a certain photocatalytic degradation activity, fine renew-ability and high mechanical strength. The pore-creating function of NaCl particles enhanced the immobilized photocatalyst's photocatalytic performance evidently. The photo-catalytic treatment of tetracycline solution by the immobilized catalyst presented the removal efficiency of over 90 % in 120 min. In addition, after the degradation, the biodegradability of the solution was enhanced evidently due to the generation of readily biodegradable organic intermediates. This study mainly presents a new method to prepare the immobilized HC/BiVO4 photocatalyst promoting the application of photocatalytic technology in organic wastewater treatment.