Surfactant effect on photocatalytic activity of Ag-TiO2/PW nanocomposite in DR16 degradation: Characterization of nanocomposite and RSM process optimization

In this work, the effect of various surfactants including the polyethylene glycol 1000 and 400 (PEG 1000 and PEG 400) and ethylene glycol (EG) on morphology and photocatalytic activity of silver-titanium dioxide/heteropoly acid (Ag-TiO2/PW) nanocomposite were studied. The prepared nanocomposites were used for photodegradation of direct red 16 (DR16) under visible light. X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), Brunauer Emmett-Teller (BET), photoluminescence spectroscopy (PL), diffuse reflectance spectra (DRS) and fourier transform infrared FTIR were used to investigate the structural properties of the nanocomposites. Use of the surfactants in the synthesis procedure of the Ag-TiO2/PW photocatalyst showed an increase in the photocatalytic performance degrading DR16. The presence of the surfactant in the photocatalyst structure led to lower recombination rate of h+/e- in the Ag-TiO2/PW/surfactant relative to Ag-TiO2/PW nanocomposite. The results showed that by addition of the surfactants into the Ag-TiO2/PW nanocomposite, the efficiency was improved about 25% in same reaction conditions (DR16 concentration 0.025 g/L, catalyst loading 1 g/L, initial pH 5 and reaction time of 2 h). 94% photocatalytic activity was achieved for DR16 concentration 0.025 g/L at optimum conditions (initial pH 3 and catalyst loading 2 g/L) after 90 min.