Preparation and immobilization of Bi2WO6/BiOI/g-C3N4 nanoparticles for the photocatalytic degradation of tetracycline and municipal waste transfer station leachate

• Bi 2 WO 6 /BiOI/g-C 3 N 4 photocatalyst presented an effective tetracycline degradation. • A new process for the immobilization of photocatalyst nanoparticles was developed. • The immobilized photocatalyst had high mechanical strength and catalytic activity. • The photocatalytic degradation presented 56.1% COD removal and 50.4% TOC removal. • The photocatalytic degradation enhanced the biodegradability of MWTS leachate. Bi 2 WO 6 /BiOI nanoparticles were embedded into graphitic carbon nitride (g-C 3 N 4 ) to fabricate a new visible-light-driven photocatalyst (Bi 2 WO 6 /BiOI/g-C 3 N 4 ). Furthermore, the immobilization of Bi 2 WO 6 /BiOI/g-C 3 N 4 was performed by a new method characterized by using polytetrafluoroethylene (PTFE) as an adhesive agent and boric acid (H 3 BO 3 ) as a pore-forming agent. Bi 2 WO 6 /BiOI/g-C 3 N 4 possesses the higher photocatalytic performance than Bi 2 WO 6 /BiOI and g-C 3 N 4 for tetracycline degradation because of the enhancement of light absorption and electron/hole (e – /h + ) pairs separation. After immobilization, Bi 2 WO 6 /BiOI/g-C 3 N 4 still remained considerable activity and stability. For the degradation of tetracycline, the immobilized photocatalyst presented the degradation rate of over 90 % within 120 min, whereas the photocatalytic degradation of municipal waste transfer station (MWTS) leachate for 28 h presented the chemical oxygen demand (COD) removal rate of 56.1 % and the total organic carbon (TOC) removal rate of 50.4 %. Additionally, the biodegradability of the two test solutions was enhanced evidently after the photocatalytic degradation. This work mainly provides a new photocatalyst immobilization method to promote the large-scale application of photocatalytic degradation.