Surfactant-aided sol-gel synthesis of TiO ₂ –MgO nanocomposite and their photocatalytic azo dye degradation activity

In this work, a surfactant-aided TiO ₂ –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 TiO ₂ 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 TiO ₂ 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 TiO ₂ photocatalysts.