Application of response surface methodology to optimize the sonophotocatalytic process for the removal of phenol from aqueous solution

In this research, a series of discontinuous experiments were carried out in the direction of sonophotocatalytic degradation of phenol using Fe3O4@SiO2@TiO2 magnetic nanocomposite from aqueous solution by using Design of Experiments (DOE) software based response surface method (RSM) in central composite design (CCD). The variables studied in the mentioned process included pH, catalyst dose, H2O2 concentration, and contact time with UV light, and the combined effect of all 4 variables were investigated simultaneously in order to optimize the maximum removal of phenol. Also, the results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed that the produced photocatalyst has nano dimensions and that the core-shell structure has been successfully formed. According to the results obtained in this study, the highest efficiency of the sonophotocatalytic process was obtained at pH = 4, H2O2 concentration 8 ml/liter, catalyst dose 2.3 g/liter and time 93 minutes with a removal rate of 83%. Among the investigated parameters, pH and time had the greatest effect on the phenol removal rate. The reusability of the catalyst reached 66% during 5 stages of the recovery cycle process. Experimental findings showed that the use of Fe3O4@SiO2@TiO2 catalyst in the presence of ultrasound waves has an increasing effect in the photocatalytic decomposition of phenol. Therefore hybrid systems can be used as a promising technology in water and wastewater treatment processes.