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Fe3O4/TiO2/Ag nanocomposites with different amounts of silver were prepared using the sol–gel method. X-ray diffraction, energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, Brunauer–Emmett– Teller surface areas, and the vibration sample magnetometry were used to characterize these nanocomposites. Photocatalytic activity of the nanocomposites was examined via decomposing the solution of 2,4-dichlorophenol (2,4-DCP) exposed to UV/Vis irradiation. Exposing the solution to pure TiO2and ternary Fe3O4/TiO2/Ag nanocomposite, we obtained 30% and almost 60% degradation of 2,4-DCP after 180 min irradiation, respectively. The excellent photocatalytic activity of Fe3O4/TiO2/Ag samples can be related to the surface plasmon resonance effect of Ag nanoparticles deposited on Fe3O4/TiO2nanocomposite. The Fe3O4/TiO2/Ag nanocomposites were retrieved from the solution of reaction through a constant magnetic bar, followed by assessing their photocatalytic activity after three repetitive recycling cycles. Afterward, this nanocomposite might be applied as an efficient and reusable photocatalyst.

This study presents a multicomponent photocatalytic system using simple impregnation-calcination of Cu2O particles followed by photodeposition of different amounts of Ag on TiO2nanoparticles (TCA(a) samples) with high photocatalytic efficiency for 2,4-dichlorophenol (2,4-DCP) degradation under visible light. The obtained samples were characterized through X-ray diffraction, field-emission scanning electron microscopy with energy dispersive X-ray spectroscopy, UV-Vis diffuse reflectance spectroscopy, N2physisorption, and transmission electron microscopy techniques. The synthesized samples exhibited a high visible-light photocatalytic activity for 2,4-DCP degradation (50%) compared with pure TiO2(28%), which is attributed to the synergetic effect of AgCl, Ag, and Cu2O on TiO2nanoparticles. Furthermore, a dual Z-scheme charge transfer pathway is proposed and discussed for photocatalytic reactions taking place over the prepared photocatalysts. The degradation reactions follow first-order kinetics. Finally, reusing the best photocatalyst (TCA(1.2) did not result in any decline in its catalyst activity for 2,4-DCP degradation under visible light after four cycles.

In the present study, binary nanocomposites were prepared by hydrothermal growth of titanium dioxide nanosheets (TNs) on different amounts (5, 10, and 15 mg) of monolayer graphene oxide (TNs/rGO(x)). Cadmium sulfide (CdS) nanoparticles with various Cd/Ti molar ratios (0.35, 0.70, 1.40) were impregnated on the TNs/rGO(x) samples by the hydrothermal procedure. The formation of anatase phase for TNs, reduction of graphene oxide, and synthesis of CdS nanoparticles were proved by powder x-ray diffraction (PXRD) and Raman analyses. The photoluminescence (PL) and diffuse reflectance spectroscopy (DRS) analyses showed that the simultaneous presence of rGO and CdS in the synthesized samples decreased the electron-hole recombination and extended the spectral response of TNs to the visible light region. The highest obtained percentage removal of tetracycline (TC) (as a pharmaceutical pollutant model) was 84% under 180 min of visible light irradiation in the presence of the CdS-TNs/rGO(5) sample. Active species scavenging tests showed that O2•-was major active species in the removal process. In addition, the application of artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) in modeling the removal of tetracycline (TC) was evaluated in this study. The experimental results confirmed that the integration between adsorption and photocatalysis processes leads to a significant impact on the removal of TC.