Search

A visible-light-driven and magnetic photocatalyst Ag/Fe,N-TiO 2 /Fe 3 O 4 @SiO 2 (AgFeNTFS) was synthesized through a multi-step method. AgFeNTFS was tested for the photocatalytic disinfection of Escherichia coli (E. coli) and degradation of bisphenol A (BPA) under visible light irradiation, separately and simultaneously. The results showed that a 6.3-log reduction in cell density of E. coli was achieved and BPA (2 mg/L) was completely removed by AgFeNTFS in the separated photocatalytic processes within 120 min. In the simultaneous process, the photocatalytic disinfection of E. coli was not influenced in the presence of BPA, but the efficiency of BPA degradation was dropped by 10%. This was likely due to the competition for the same dominant reactive species of O 2 - and H 2 between E. coli and BPA in the simultaneous process, as evidenced by the scavenger study and the interactions between the pollutants and AgFeNTFS. Moreover, the simultaneous photocatalytic activity of E. coli disinfection and BPA degradation by AgFeNTFS was investigated in the sewage obtained from a local wastewater treatment plant. The photocatalysis treated sewage could meet with the local disinfection discharge standard with a 3-log reduction of E. coli after 90 min, and a complete removal of BPA was achieved simultaneously after 360 min. Moreover, AgFeNTFS showed high magnetic separation efficiency and had a good reusability over three cycles for the simultaneous photocatalytic disinfection and degradation of BPA in both synthetic water and sewage. This study provides insights on the application of a reusable magnetic photocatalyst for simultaneous disinfection and degradation of BPA in sewage.2 between E. coli and BPA in the simultaneous process, as evidenced by the scavenger study and the interactions between the pollutants and AgFeNTFS. Moreover, the simultaneous photocatalytic activity of E. coli disinfection and BPA degradation by AgFeNTFS was investigated in the sewage obtained from a local wastewater treatment plant. The photocatalysis treated sewage could meet with the local disinfection discharge standard with a 3-log reduction of E. coli after 90 min, and a complete removal of BPA was achieved simultaneously after 360 min. Moreover, AgFeNTFS showed high magnetic separation efficiency and had a good reusability over three cycles for the simultaneous photocatalytic disinfection and degradation of BPA in both synthetic water and sewage. This study provides insights on the application of a reusable magnetic photocatalyst for simultaneous disinfection and degradation of BPA in sewage., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A highly recoverable titanium dioxide-graphene oxide (TiO2-GO) composite was developed by a facile method of ultrasonic treatment of GO nanosheets and TiO2 nanoparticles, which should overcome the separation problem of nanosized TiO2 from treated water. Separability of the prepared samples was systematically investigated by gravity settling experiments. The samples' photocatalytic activity for stormwater disinfection was also studied under the irradiation of a solar simulator. The results demonstrated that TiO2-GO showed high efficient separability due to its accelerated settling behaviour. Zeta-potential analysis showed that the accelerated sedimentation of the catalyst was attributed to the aggregation of TiO2-GO resulting from the electrostatic attraction between TiO2 and GO. The TiO2-GO composite with a mass ratio of 100:2 (TiO2-2%GO) achieved both higher separability and good photocatalytic activity for stormwater disinfection. Its suspension became clear (turbidity < 50 NTU) after 8 h of sedimentation, while 99.5% of E.coli were deactivated in 90 min. The TiO2-GO composite exhibited excellent durability; no apparent change in the separability of TiO2-2%GO was observed after 10 treatment cycles (15 h in total), while only slight decrease in the photocatalytic activity was noted. In conclusion, the developed TiO2-GO composite showed promising results for stormwater disinfection., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Photocatalysis has received ever‐growing attention as a promising alternative to traditional water treatment technologies for waterborne biohazard inactivation. Due to unique optical, electronic, physicochemical properties and feasibility of functional architecture assembly, two‐dimensional (2D) nanomaterials have become important in developing novel photocatalysts. This review summarizes the recent progress in configuring nanostructures with 2D materials as building blocks for photocatalytic water disinfection. In this review, five categories of 2D nanomaterials, that is, graphene, graphitic carbon nitride, 2D metal oxides and metallates, metal oxyhalides and transition metal dichalcogenides, for photocatalytic pathogen inactivation are introduced. First, the synthesis process, nanostructure engineering and disinfection performance of 2D‐based photocatalysts are reviewed in categories. In the following section, the bacteria destruction mechanism based on the generation and roles of reactive species (RSs) is presented. Moreover, the effects of the chemical characteristics of the water matrix on photocatalytic bactericidal performance are discussed. Finally, the challenges regarding the development and application of 2D‐based photocatalysts for highly efficient water sterilization are highlighted. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Coupling TiO 2 with WO 3 to develop photocatalytic heterojunctions is one of the most widely used strategies to realize their superior photoactivity. However, the interfacial charge transfer in these heterojunctions is not efficient to achieve an optimized activity. For the first time, the present study reports a facile hydrolysis-hydrothermal approach, whereby ultradispersed TiO 2 nanocrystals and WO 3 nanorods are concurrently anchored onto reduced graphene oxide (rGO) and formed a novel Z-scheme heterojunction photocatalyst TiO 2 /rGO/WO 3 (TRW). Transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence spectra (PL) are employed to characterize TRW. Control experiments indicate that, in the synthesis process, glucose and the by-product sodium chloride from the hydrolysis reactions are critical for forming highly dispersed and uniform-sized TiO 2 nanocrystals and WO 3 nanorods. Compared with TiO 2 /WO 3 nanocomposites, TRW shows enhanced activity for bacterial inactivation under simulated solar light. As confirmed by electrochemical characterizations and the reactive oxygen species, rGO in TRW suppresses the recombination of electron-hole pairs and boosts the O 2 reduction reactions during photocatalytic process. Z-scheme electron transfer in TRW is proposed based on surface redox reactions and XPS analysis after light irradiation. This study could provide a new clue for designing graphene-based heterojunction photocatalysts for environmental applications. [ABSTRACT FROM AUTHOR]

Graphene is widely used as a catalyst support for improved charge separation in TiO 2 photocatalysis. However, the surface oxygen reduction activity of TiO 2 /graphene might be hindered due to the electron storage ability of graphene. In this study, highly dispersed TiO 2 and carbon dots (C-dots) co-decorated reduced graphene oxide (CTR) is synthesized via a simple hydrothermal reaction using TiCl 4 and glucose. Transmission electron microscope, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis and Fourier transform IR spectroscopy are employed to characterize the CTR nanocomposite. The comparison experiment confirmed that C-dots were sourced from the carbonization of glucose. Glucose and TiCl 4 which are mutual dispersants, are critical for forming highly dispersed and uniform-sized C-dots and TiO 2 nanocrystals. With well dispersed TiO 2 and C-dots at separated sites of reduced graphene oxide surface, CTR shows enhanced photocatalytic bacterial inactivation performance under simulated solar light. As confirmed by the reactive oxygen species production, the generation of superoxide anion (O 2 − ) and hydrogen peroxide (H 2 O 2 ) is improved. The electrochemical characterization reveals that charge separation in CTR photocatalysis is also promoted. Taken together, the concurrently improved charge separation and surface oxygen reduction activity contribute to an accelerated photocatalytic bacteria inactivation process. [ABSTRACT FROM AUTHOR]