Catalytic activity enhancement of a Fe3O4@SiO2 yolk-shell structure for oxidative degradation of acetaminophen by decoration with copper

Abstract

The occurrence of pharmaceuticals in the environment has received wide attention, and they have recently been considered as emerging organic contaminants. Since conventional wastewater processes are not particularly effective, the development of new technology that can completely remove pharmaceutical compounds in aquatic environments is an urgent need. Recently, iron-copper bimetallic catalysts have attracted increasing attention, and they are known as good Fenton reagents for the degradation of persistent organic pollutants. In this study, yolk-shell structured Fe3O4@SiO2 was prepared via a spontaneous self-transformation process, and it was decorated with copper nanoparticles (Fe3O4@SiO2@Cu) to produce a novel catalyst aimed at the rapid catalytic oxidation of acetaminophen in the heterogeneous Fenton reaction. Different ratios of Fe3O4 and copper were obtained by varying the precursor amounts of yolk-shell and copper salt. The catalyst properties were characterized by several techniques to verify the successful synthesis of the targeted materials. The results demonstrated that the Fe3O4@SiO2@Cu was controllably prepared, copper nanoparticles were firmly immobilized on the mesoporous silica shell, and the decoration of copper did not impact the yolk-shell structure of the precursor material. The catalytic activity of Fe3O4@SiO2@Cu was much better than that of Fe3O4@SiO2 for the degradation of acetaminophen. The catalytic performance of Fe3O4@SiO2@Cu increased with increasing copper content. Radical scavenging studies showed that •OH is the main reactive species contributing to acetaminophen degradation. In addition, the catalyst also exhibited good separation and satisfactory regeneration properties. The decoration of copper nanoparticles onto the yolk-shell structure Fe3O4@SiO2 was proved to be an attractive alternative method to obtain a novel bimetallic catalyst applied in heterogeneous Fenton-like system for the removal of persistent pharmaceuticals from wastewater.