TiO2 nanocomposite ceramics doped with silver nanoparticles for the photocatalytic degradation of methylene blue and antibacterial activity against Escherichia coli

Abstract

The development of highly efficient and stable photocatalysts for wastewater treatment has been identified as one of the most important environmental challenges facing the world. In this study, titanium dioxide (TiO2) fibrous nanocomposites doped with novel silver nanoparticles (Ag NPs) were synthesized by combining sol–gel and electrospinning methods. For this aim, Ag NPs were fabricated via the microwave-assisted green synthesis method by using soluble starch as a reducing agent. The produced electrospun nanocomposites doped with Ag NPs were calcined at 700 °C for the decomposition of the polymer from the nanofiber structure and attain the anatase phase formation of TiO2. Also, pure TiO2 ceramic membrane was synthesized in the same way to compare the doping effect of Ag NPs on nanocomposite material. After the heat treatment process, Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques were utilized to characterize the morphological and structural properties of nanocomposite membranes. Different weight percentages of Ag NPs (2% and 2.5%) were used to investigate the effect of the Ag concentration on antimicrobial activity against Escherichia coli (E. coli), and the maximum antibacterial activity (99.999%) was achieved by TiO2 nanocomposite membrane doped with 2.5% Ag NPs. Based on the FTIR spectra, it was determined that the polymer was successfully removed by calcination at 700 °C. XRD, XPS and EDX results showed that Ag nanoparticles were incorporated and dispersed in TiO2 ceramic nanofibrous structure successfully. The photocatalytic ability of the nanofiber membranes was measured according to methylene blue (MB) concentration change in the aqueous solution under UV irradiation. The very high degradation rate of MB of 94.6% was reached with TiO2 nanocomposite membrane doped with 2.5% Ag NPs showing the synergistic effect of TiO2 and Ag NPs. The results indicate that Ag NPs–TiO2 nanocomposite membrane could efficiently degrade MB upon irradiation with UV light, showing greater photocatalytic activity and antibacterial activity than the pure TiO2 nanofibers.