Ag/Bi4O5I2/reduced graphene oxide as a visible-light active nanophotocatalyst for pharmaceutical pollutants from wastewater

Abstract

Novel plasmonic Ag–Bi4O5I2/carbonaceous nanocomposites (reduced graphene oxide [rGO]/walnut shell active carbon [WShAC]) were prepared through a sonication-mediated solvothermal process. Such materials were used for the photo-decomposition of several fluoroquinolone antibiotics, such as tetracycline hydrochloride, ofloxacin, and levofloxacin under simulated solar-light conditions (average intensity 2.960 W/cm2). The results of Brunauer-Emmett-Teller–Barrett-Joyner-Halenda (BET–BJH) in combination with field emission scanning electron microscopy, confirmed that carbonaceous materials could make suitable heterostructures with Bi4O5I2 using ultrasound waves, thereby increasing specific surface area from 20.3 m2/g for Bi4O5I2 to 35.6 m2/g for Ag–Bi4O5I2/WShAC and 40.6 m2/g for Ag–Bi4O5I2/rGO. Furthermore, the pore size of Bi4O5I2 increased from 9.1 nm to 21.6 nm when forming Ag–Bi4O5I2/rGO. Ag–Bi4O5I2/rGO indicated remarkable activity, achieving the degradation of 90.2% for tetracycline hydrochloride, 60.9% for ofloxacin, and 38.5% for levofloxacin after 180 min of simulated solar irradiation that made this sample to be chosen as a standout candidate for further investigation and potential applications. Concerning the constant rate for eliminating 50 mg/L of tetracycline, the constant rate was improved 2.25 and 4.75 times for Ag–Bi4O5I2/WShAC and Ag–Bi4O5I2/rGO, respectively. Also, the Ag–Bi4O5I2/rGO nano photocatalyst showed excellent stability after four cycles, in which the reusability dropped only 5%.