High-efficiency removal of ciprofloxacin by persulfate activated with 3D Bi2WO6/g-C3N4/GA Z-scheme heterojunction under simulated sunlight

Bi2WO6/g-C3N4 (BC) Z-scheme heterojunction assembled with graphene aerogel (GA) was successfully prepared by a simple hydrothermal associated with natural seasoning method. The physico-chemical, morphological and photoelectric properties of the Bi2WO6/g-C3N4/GA (BCGA) composite was characterized by various instruments, and its photocatalysis performance for persulfate (PDS) activation was explored in the removal of ciprofloxacin (CIP) under simulated sunlight (SSL) irradiation. The optimal mass ratio of BC was 30 % (abbreviated as BCGA-30) in BCGA. Under the optimal conditions (10 mg/L CIP, 50 mg/L PDS, pH = 6.66 and 0.2 g/L BCGA-30), the degradation rate of CIP was 94.3 %, which was 4.18 times that of BC. As the carrier of BC, GA could promote the light absorption and the photo-induced electron transfer of BCGA-30. The removal efficiency of CIP was remained at 80.2 % after five cycles, illustrating that BCGA-30 had an excellent repeatability. Based on the results of the energy band structures, HR-TEM, XPS and free radical quenching experiments, the heterojunction type of composites and possible photocatalytic activation mechanism during CIP degradation were confirmed over BCGA-30/PDS/SSL system. The BCGA-30/PDS/SSL system might be a potential treatment process for the removal of antibiotics wastewater.