Visible-Light-Driven Mitigation of Rhodamine B and Disinfection of E. coli Using Magnetic Recyclable Copper-Nitrogen Co-doped Titania/Strontium Ferrite/Diatomite Heterojunction Composite

The researches on the development of novel powdery photocatalysts have been conducted for decades, yet their low reusability in suspension system is still the bottleneck which hinders their large-scale application. An alternative method to overcome this issue is developing magnetic recyclable photocatalytic composite. In this work, we fabricated copper-nitrogen co-doped titania/strontium ferrite/diatomite (CN-TSD) ternary composite via sol-gel route. The physicochemical properties of the composite were characterized and analyzed, and its photocatalytic activity was investigated via the decomposition of organic dye Rhodamine B and disinfection of bacteria Escherichia coli under visible light illumination. Charge transfer occurred at the heterojunction interface between titania and strontium ferrite lowered the recombination of charge carriers, and thus promoted photodecomposition efficiency. The photodecomposition rate was further accelerated by the high adsorption performance of diatomite, due to the adsorption and decomposition synergism between photocatalytic components and diatomite. The best doping amount and catalyst dosage are determined, and the corresponding catalyst sample showed its photo-decomposition percentage as 97.1% after 2.5 h, and showed its photo-disinfection percentage of 94.0% after 2 h. CN-TSD composite could simply be separated from waterbody via an external magnet. After five turns of repetition tests, only slightly decrease of decomposition or disinfection efficiency could be observed. This composite was promising to be applied in wastewater remediation process, due to its good visible-light-driven photocatalytic activity, as well as its good reusability and stability.