Multifunctional BiPO4/TiO2/rGO composite for enhancement removal of malachite green and levofloxacin via adsorption and visible-light photocatalysis synergy

Herein, we prepared a multifunctional BiPO4/TiO2/rGO (BTG) composite photocatalyst through a hydrothermal process and explored its structural and morphological characteristics through various characterization techniques. BTG displays an optimal adsorption-photocatalytic effect, which can remove 100% of malachite green (MG) and 88% of levofloxacin (LEO) in 3 h (BTG dosage = 0.67 g/L, initial MG and LEO = 20 mg/L, T = 298 K) through dark adsorption. Importantly, BTG exhibited enhanced degrading ability with 100% decomposition ration for MG and LEO after 45 and 165 min visible-light irradiation, which was 17.1 and 16.9 times that of neat BiPO4, respectively. Adsorption experiment, DRS, PL, Transient photocurrent and EIS analyses revealed that the multifunctional BTG composite not only demonstrated high adsorption capacity for MG and LEO, but also exhibited a narrow band gap energy, wide visible light absorption, efficient charge transfer and suppressed carrier recombination. In addition, the BTG also showed good stability towards the removal of MG and LEO with high removal efficiency throughout the 5 adsorption-photocatalysis cycles. Finally, the photocatalytic mechanism of MG and LEO by BTG was discussed based on free radical trapping experiments and Mott-Schottky measurements, which may give an idea for future design and construction of environmentally friendly adsorptive photocatalysts.