The fabrication of magnetic recyclable nitrogen‐doped titanium dioxide/calcium ferrite/diatomite heterojunction nanocomposite for improved visible‐light‐driven degradation of tetracycline.

BACKGROUND: Powdery photocatalysts have long been studied in various aspects, yet their low recovery in suspension systems remains the bottleneck hindering their practical application. An alternative method to overcome this shortcoming is to develop magnetic recyclable ferrite‐based hybrid photocatalysts. In this work, we prepared a nitrogen (N)‐doped titania (TiO2)/calcium ferrite (CaFe2O4)/diatomite (Dt) (N‐TCD) ternary hybrid via the sol–gel method. The physicochemical properties of various hybrid catalysts were characterized and studied, and their photocatalytic properties were evaluated via the degradation of the antibiotic tetracycline (TC) under visible light. RESULTS: The photodegradation rate of TC was accelerated by the high adsorption ability of Dt, due to the adsorption and degradation synergistic effect between catalysts and substrate Dt. The ternary composite indicated higher degradation rate than binary ones, implying the interaction between three components. Based on the degradation results, the optimal N dopant amount and catalyst dosage were determined. CONCLUSIONS: The formation of heterojunction between N‐doped TiO2 and CaFe2O4 hindered the recombination of photo‐induced charge carriers and improved the photocatalytic activity. The ternary N‐TCD composite could simply be recovered from TC solution via an external magnet, and repetition tests indicated no obvious decrease of photoactivity, even after five runs. This nanocomposite was considered appropriate for application in wastewater remediation processes, thanks to its high photocatalytic efficiency under visible light irradiation, as well as its good reusability and stability. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]