Surfactant-aided sol-gel synthesis of TiO2-MgO nanocomposite and their photocatalytic azo dye degradation activity

In this work, a surfactant-aided TiO2-MgO nanocomposite (Ti-M-S) was successfully synthesized by a sol-gel process with the aid of sodium dodecyl sulfate as a structure-directing anionic surfactant. The results demonstrated the effectiveness of this approach for controlling both the amount and the distribution of MgO nanoparticles within the TiO2 framework after calcination. The photocatalytic activity of the synthesized nanocomposite for degradation of methyl orange (MO) and methylene blue (MB) dyes used as a model wastewater contaminant was investigated under visible light irradiation. The synthesized nanocomposite was systematically characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis. The decolorization results revealed that the Ti-M-S1 (with an anionic surfactant: sodium dodecyl sulfate) and Ti-M-S2 (with a non-ionic surfactant: Triton X-100) nanocomposites showed much more photocatalytic activity than the pure TiO2 did under visible light. MB and MO dye removal efficiencies of 82.4% and 77.8 %, respectively, were achieved by Ti-M-S1 (1%) within about 120 min and no further changes in the uptake were observed up to 24 h. This confirmed the suitability of the synthesized nanocomposite for use as a photocatalyst under visible light with the added advantage of increasing the versatility of potential applications for TiO2 photocatalysts.