Amino-functionalized synthesis of MnO2-NH2-GO for catalytic ozonation of cephalexin

Abstract

Catalysts such as MnO2 always play a critical role in catalytic ozonation, which is applied extensively in water treatment for disinfection, odor removal and organic pollutants degradation. To improve the performance of catalytic ozonation, we design and synthesize a catalyst of amino-functionalized hybrid of MnO2 and graphene oxide (MnO2-NH2-GO) with hydrothermal method, and then use it to catalyze the ozonation of cephalexin (CLX), one of β-lactams antibiotics frequently detected as refractory pollutants in aquatic environment. The MnO2-NH2-GO shows much higher catalytic performance than both MnO2 and MnO2-GO in the ozonation of CLX, in which the free radicals of ·O2− play a dominated role and the Mn3+/Mn4+ acting as active sites react with ozone to promote the formation of ·O2− with the help of the enhanced electron transfer facilitated by GO. The MnO2-NH2-GO also shows more stable catalytic performance than MnO2-GO due to the strong covalent bonds bridged by amino to MnO2 and GO to prevent the decoupling of GO from MnO2. This work provides a method to design a smart catalyst for ozonation with high catalytic performance and stability.