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

Abstract

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 (TiO 2 )/calcium ferrite (CaFe 2 O 4 )/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 TiO 2 and CaFe 2 O 4 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.

Recent Achievements in Development of TiO2-Based Composite Photocatalytic Materials for Solar Driven Water Purification and Water Splitting

“…Such behavior is confirmed by studying the degradation pathway of TC; it was found that the TC intermediates match those that formed through radical driven reactions undergoing in the first step demethylation and hydroxylation. The second step considered the removal of functional groups (amino, hydroxyl, and methyl) and further ring opening reactions that are mainly mediated by photogenerated h + , yielding small fragments that were eventually mineralized [44]. Such a pathway confirmed the dual role of photogenerated h + , as a promotor •OH generation and as sites for the direct oxidation of adsorbed organics.…”

“…Hence, the contribution of H 2 O 2 in such a system can be described through restraining e − /h + recombination and increasing HO• generation in the system, as in Equation 1 [42,43]. Spinel ferrites band positions match TiO 2 , thus possessing compatibility to form a heterojunction (Type II Heterojunction) [44][45][46][47].…”

“…The literature provides applications of MFe 2 O 4 /TiO 2 materials as photocatalysts in treatment of CECs, as in the case of previously discussed TiO 2 -based composites, however, it should be noted that authors within such composites used modified TiO 2 (Table 3). Hence, Chen et al [44] studied photocatalytic degradation of TC and its derivatives using N-doped TiO 2 /CaFe 2 O 4 /diatomite, and reported 91.7% removal of TC within 150 min. under visible light irradiation.…”

“…Proposed mechanism for the tetracycline (TC) photodegradation process using N-doped TiO 2 /CaFe 2 O 4 / diatomite[44].…”