Application of response surface methodology for optimization of operational variables in photodegradation of phenazopyridine drug using TiO2/CeO2 hybrid nanoparticles

Abstract

In the present work, a powder mixture of the TiO 2 and CeO 2 solid oxides was used for preparation of TiO 2 /CeO 2 hybrid nanoparticles. Crystallite size and structure of prepared TiO 2 /CeO 2 hybrid nanoparticles were determined by X-ray diffraction and transmission electron microscopy techniques. The effect of operational variables such as catalyst dosage, initial drug concentration, irradiation time, and distance of the solution from UV lamp was predicted and optimized in the photocatalytic removal of phenazopyridine (PhP) using response surface methodology. The results showed that the predicted values of removal efficiency were found to be in good agreement with the experimental results with a correlation coefficient (R 2 ) of 0.9542. The optimum operational conditions were found to be: catalyst dosage of 0.41 g L −1 , initial drug concentration of 6.61 mg L −1 , irradiation time of 30 min, and distance of the solution from UV lamp of 2 cm. Under the optimized conditions, the maximum removal rate (97.74%) of PhP was achieved.

Hybrid Homogeneous and Heterogeneous Photocatalytic Processes for Removal of Triphenylmethane Dyes: Artificial Neural Network Modeling

“…By varying the TiO 2 −SiO 2 dosage from 0.1 to 0.4 g L −1 , the removal rate of AF and MG dyes improved from 19 and 42% to 59 and 89%, respectively. This can be due to an increase in the number of accessible catalytic and adsorption sites on the TiO 2 −SiO 2 surface . An improvement on the removal efficiency of the hybrid process with an increase in the TiO 2 −SiO 2 dosage is not remarkable for concentrations of >0.4 g L −1 .…”

“…This phenomenon enhances the probability of charge‐carrier recombination and prompts the end of the photocatalytic oxidation . With increasing the initial dye concentration, more dye molecules are adsorbed on the TiO 2 −SiO 2 surface, and consequently the chance of forming reactive species such as • OH radicals will be diminished . On the other hand, with increases in the initial concentration, the dye solution gets impermeable to UV irradiation because the molar extinction coefficient of the dyes at 254 nm (the wavelength of UV lamp) is very high.…”

“…On the other hand, with increases in the initial concentration, the dye solution gets impermeable to UV irradiation because the molar extinction coefficient of the dyes at 254 nm (the wavelength of UV lamp) is very high. In that case, the UV photons get intercepted before reaching the photocatalysts surface .…”

“…An improvement on the removal efficiency of the hybrid process with an increase in the TiO 2 −SiO 2 dosage is not remarkable for concentrations of >0.4 g L −1 . High turbidity of the solution caused by high catalyst loading leads to a reduction in UV light penetration into the solution . A further increase in the TiO 2 −SiO 2 dosage from 0.4 to 0.6 g L −1 decreased the removal rate of AF and MG dyes from 59 and 89% to 55 and 82%, respectively.…”

“…The preparation of TiO 2 nanoparticles supported on SiO 2 was performed via impregnation method . First, a powder mixture of 1 g SiO 2 and TiO 2 , 50:50 w/w, was ground completely in an agate mortar.…”