The experimental design methodology was used to model and optimize the operational parameters of the photocatalytic degradation of Acid Red 73 using immobilized TiO 2 nanoparticles. Four experimental parameters were chosen as independent variables: pH, initial dye concentration, H 2 O 2 concentration, and anion concentration. A multivariate experimental design was used to establish a quadratic model as a functional relationship between the efficiency of Acid Red 73 degradation (response) and four independent variables. The degradation efficiency was significantly affected by the initial dye concentration and the pH. The optimal values of the parameters were found to be a pH of 3, an initial dye concentration of 25 mg/L, an H 2 O 2 concentration of 0.5 mg/L, and an anion concentration of 0.69 mg/L. The degradation efficiency approached 92.24% under optimal conditions. Regression analysis with an R 2 value of 0.9785 indicated a satisfactory correlation between the experimental data and predicted values.

Abstract:The sol-gel method was used to synthesize nickel-alumina catalysts with various nickel loadings. Chemical and physical properties of support and supported nickel were characterized by TGA, DTA, EDX, SEM, BET, XRD and TPR techniques. Calcination temperature (500 • C) was determined by performing thermogravimetric analysis (TGA) and differential thermal analysis (DTA) on the samples. Energy dispersive X-ray (EDX) was used to determine the actual content of nickel on alumina. N 2 adsorption test revealed that the specific surface area varied between 550 and 223 m 2 /g for pure alumina and 30%Ni/Al, respectively. X-ray diffraction (XRD) patterns showed no peaks due to NiO species and NiO species were well dispersed on the support by formation of NiAl 2 O 4 phase. Temperature-programmed reduction (TPR) indicated that the nickel species mainly presented in NiAl 2 O 4 phase and small amount of NiO. In the 20 percent nickel loading, the surface NiAl 2 O 4 phase, which is between NiO and bulk NiAl 2 O 4 phases in terms reducibility, was formed considering as a successful result.

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