17 α-Ethinylestradiol Degradation in Continuous Process by Photocatalysis Using Ag/Nb2O5 Immobilized in Biopolymer as Catalyst

Abstract

This study describes the application of Ag/Nb 2 O 5 catalysts, suspension and spheres alginate immobilized for the degradation of 17α-Ethinylestradiol (EE2). The techniques used to characterize the photocatalysts were as follows: X-ray diffraction (XRD), N 2 adsorption-desorption analysis (BET), point charge zero charge (PZC), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Different catalyst calcination temperatures were studied by keeping the silver metal loading at 5%. Among the operational conditions analyzed were pH, catalyst concentration, the emitting source of radiation and the inlet flow rate (in continuous operation). The results of the experiments performed initially with the catalyst in suspension revealed that the highest catalytic activity in the degradation of EE2 was the 5%Ag/Nb 2 O 5 catalyst calcined at 973 K, which removed 77.7% of the initial pollutant concentration in 120 min of reaction. The immobilization of the catalyst in alginate spheres resulted in a degradation reduction, being able to degrade 69.2% of the initial EE2 in a batch system. In the continuous system, the immobilized catalyst obtained a total degraded of 37.3%, with a flow rate of 10 L•h −1 . Catalyst reuse was promising, even dropping the removal, degrading around 27% of the initial EE2 concentration in the third cycle of use. KeywordsSpheres alginate • Emerging pollutants • Contaminants of emerging concern • Advanced oxidation process • Thermal treatment