The fabrication of magnetic recyclable nitrogen modified titanium dioxide/strontium ferrite/diatomite heterojunction nanocomposite for enhanced visible-light-driven photodegradation of tetracycline

Abstract

Powdery photocatalyst has long been studied in various aspects, yet its low recovery in suspension system is still the bottleneck which hinders its practical application. An alternative method to overcome this shortcoming is to develop magnetic recyclable ferrite-based hybrid photocatalyst. In this work, we prepared nitrogen modified titania/strontium ferrite/diatomite (N-TSD) ternary hybrid via sol-gel method. The physicochemical properties of various hybrid catalysts were characterized and studied, and their photocatalytic properties were evaluated via the degradation of antibiotic tetracycline (TC) under visible light. The formation of heterojunction between N modified TiO2 and strontium ferrite hindered the recombination of photo-induced charge carriers and improved the photocatalytic activity. The photodegradation rate of TC was accelerated by the high adsorption ability of diatomite, due to the adsorption and degradation synergistic effect between catalysts and substrate diatomite. Based on the degradation results, the optimal N dopant amount, as well as optimal catalyst dosage was determined. The ternary N-TSD composite could simply be recovered from TC solution via an external magnet, and the repetition tests indicated no obvious decrease of photoactivity, even after 5 turns. This nanocomposite was considered appropriate to be applied in wastewater remediation process, thanks to its high photocatalytic efficiency under visible light irradiation, as well as its good reusability and stability.