Synthesis of Cu 3 P/SnO 2 composites for degradation of tetracycline hydrochloride in wastewater.

Antibiotic drugs have become dominating organic pollutants in water resources, and efficient removal of antibiotic drugs is the priority task to protect the water environment. Cu 3 P/SnO 2 photocatalysts of various Cu 3 P loadings (10-40 wt% Cu 3 P) were synthesized using a combination of hydrothermal synthesis and a partial annealing method. Their photocatalytic activity was tested for tetracycline hydrochloride (TC-HCl) degradation under visible light irradiation. Cu 3 P/SnO 2 samples were characterized by X-ray diffraction (XRD), N 2 -adsorption, ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results showed that the p-n type heterostructure between Cu 3 P and SnO 2 was successfully constructed, and addition of Cu 3 P to SnO 2 could improve its photocatalytic activity at an optimized loading of 30 wt% Cu 3 P. In photocatalytic degradation studies, removal rates of around 80% were found in 30 minutes of dark reaction and 140 min of photodegradation. The removal rate was superior to that of Cu 3 P and SnO 2 alone under the same experimental conditions. According to trapping experiments and electron spin resonance (ESR) measurements, photogenerated holes (h + ) and superoxide radicals ˙O 2 - were considered as the main oxidation species in the present system. Finally, the reuse experiments showed high stability of Cu 3 P/SnO 2 . This study reports Cu 3 P as a cocatalyst combined with semiconductor SnO 2 to form a highly efficient heterogeneous photocatalyst for the degradation of tetracycline hydrochloride for the first time.