Retracted: The Fabrication of Magnetically Recyclable La-Doped TiO₂/Calcium Ferrite/Diatomite Composite for Visible-Light-Driven Degradation of Antibiotic and Disinfection of Bacteria

Abstract

Powdery photocatalyst has been deeply studied due to its great potential in water treatment, yet its low recyclability is the bottleneck hindering its practical application. In this work, magnetically recyclable lanthanum-doped TiO 2 /calcium ferrite/diatomite (La-TCD) ternary composite was synthesized by sol-gel method. The physicochemical properties of this material were characterized and studied, and the photocatalytic property was evaluated by the decomposition of antibiotic oxytetracycline (OTC) and disinfection of bacteria Escherichia coli under visible light irradiation. The formation of heterojunction between La-doped TiO 2 and calcium ferrite hindered the recombination of photo-induced charge carriers and improved the photocatalytic activity. Besides, the photodecomposition of OTC was enhanced by the high adsorption ability of substrate diatomite, in other words, the adsorption and decomposition synergistic behavior between catalyst and diatomite. The optimal La doping amount, as well as composite dosage, was determined. The composite could simply be recovered from waterbody by an external magnet, and the repetition tests indicated no obvious decrease of photoactivity after five cycles. Above all, this composite presented good potential to be applied in wastewater remediation process.

Photocatalytic TiO2-Based Nanostructured Materials for Microbial Inactivation

“…Other hybrid nanocomposites, such as TiO 2 :In 2 O 3 , TiO 2 :g-C 2 N 4 , and TiO 2 :SiO 2 are currently under investigation due to their promising photoactivity and antibacterial properties [36,[44][45][46][47]. For instance, TiO 2 :In 2 O 3 photocatalysts were prepared by sol-gel route by reacting TiCl 4 and In(NO 3 ) 3 in water and then stabilized by addition of HNO 3 .…”

“…Other innovative materials recently proposed for their antimicrobial properties are La-doped TiO 2 /calcium ferrite/diatomite and TiO 2 /chitosan/graphene oxide (GO@CS@TiO 2 ) [46,47].The former was prepared by reacting ferric nitrate nonahydrate and calcium nitrate tetrahydrate in the presence of diatomite. In the next step, tetrabutyl orthotitanate and lanthanum nitrate hexahydrate were left to react in the presence of calcium ferrite/diatomite finally leading to La-doped TiO 2 /calcium ferrite/diatomite that was able to kill E. coli under visible light irradiation [46]. For preparing GO@CS@TiO 2 , in brief, GO was dispersed in ultrapure water, then CS was dissolved in acetic acid and added to GO solution obtaining nanometer film.…”

“…Another ingenious solution is based on nanocomposites also incorporating a magnetic domain, able to convey to the system magnetic properties effective in enabling their simple recovery at the end of the treatment by applying a magnetic field. Wu et al synthetized a ternary composite based on lanthanum-doped TiO 2 /calcium ferrite/diatomite with magnetic properties, and enhanced photocatalytic antibacterial activity against E. coli [46]. Another interesting alternative to achieve recoverable photoactive materials is given by nanocomposites formed of NPs coupled with micrometer structures, thus combining the advantages of the nanoscale properties with the possibility of recovering the composite by using filtration methods.…”

“…The merging of the two nanomaterials in one nanocomposite was found to play the two roles of introducing in the building material a filler, mSiO 2 , able to improve its mechanical properties, and conveying, with TiO 2 , anti-biofouling and self-cleaning activity upon UV exposure. The mSiO 2 /TiO 2 composite antibacterial activity was tested against E. coli and, after 2 h, a 67% and a 42% reduction were measured after exposure to UV light and at dark, respectively [46].…”