Novel magnetically separable g-C 3 N 4 /TiO 2 /CuFe 2 O 4 photocatalyst for efficient degradation of tetracycline under visible light irradiation: Optimization of process by RSM

Herein, a novel magnetic visible-driven g-C 3 N 4 /TiO 2 /CuFe 2 O 4 nanocomposite with excellent photocatalytic performance was successfully prepared and employed for photodegradation of tetracycline. Several analysis including X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), energy dispersive X-ray (EDX), Vibrating-Sample Magnetometer (VSM), and Ultraviolet -Visible Diffuse Reflectance Spectroscopy (UV -Vis DRS) were performed in order to study the structural, optical, magnetic, as well as morphological properties of nanocomposite. The optical band gap of gC 3 N 4 /TiO 2 /CuFe 2 O 4 heterostructure was found to be red shifted to 2.45 eV from 3.15 eV for pure TiO 2 . Enhanced separation of photoinduced electron-hole pairs and enhanced visible light absorption capacity of nanocomposite lead to a maximum tetracycline photodegradation efficiency. Response surface methodology (RSM) was used to investigate the influence four independent variables, including initial photocatalyst dosage (7 -14 g/L), TC concentration (20 -30 ppm), solution pH (5.5 -7.5), and irradiation time (20 -40 min), and optimize the TC degradation efficiency. The g-C 3 N 4 /TiO 2 /CuFe 2 O 4 nanocomposite was able to separate and recycle easily using an external magnetic field, and the results of reusability was shown its high stability after 5 cycles. Active species trapping experiments suggested that holes and hydroxyl radicals played a crucial role in the TC degradation process. Finally, a potential photocatalytic mechanism for photodegradation of TC was proposed.