Statistical modeling of p-nitrophenol degradation using a response surface methodology (RSM) over nano zero-valent iron-modified Degussa P25-TiO2/ZnO photocatalyst with persulfate

Zero-valent iron-modified Degussa P25-TiO2/ZnO nanocomposites (denoted as P25/Fe-0/ZnO) were designed and prepared via Fe-0 impregnation of P25-TiO2/ZnO and then were employed in the visible-light photocatalytic degradation of p-nitrophenol (PNP) in the presence of [K2S2O8]. Central composite design was applied for response surface modeling (RSM) to understand the influence of selected factors (pH, [Fe-0] wt% and [K2S2O8] concentration) on the degradation of PNP and to determine the interaction between the factors. The maximal PNP degradation efficiency (86.9%) was obtained with P25/1.5 wt% Fe-0/ZnO at 3 mg/L of [K2S2O8] concentration and pH 7.5. In addition, the RSM showed a satisfactory correlation between the experimental and predicted values of PNP degradation. The P25/Fe-0/ZnO photocatalyst performance was also examined degrading methyl orange and phenol and high degradation efficiency, 82 and 99%, was achieved, respectively. The structure, morphology, light absorption and photocatalytic properties of as-prepared P25/Fe-0/ZnO were studied using TEM, BET, XRD, FTIR and DRS.