Abstract

To prevent the human health risks presented by the rise of antibiotic resistant bacteria and the negative ecological impacts of large amounts of antibiotics entering the environment, it is crucial to develop effective technologies for the reduction and elimination of residual antibiotics in water.
Current conventional waste water treatment plants (WWTP) are not specifically designed to effectively remove complex organic molecules such as antibiotics. To address this problem many physical and chemical methods have been developed and tested for removal of antibiotics from environmental sources. However, these methods are highly condition based and potentially expensive. Recently, nanoscale zero-valent iron (nZVI) have gained a lot of attention for removal of wide range of organic and inorganic contaminants. It is recognized that nZVI tends to aggregate and oxidize rapidly, reducing the effectiveness and lifetime of these nanoparticles. To overcome these problems, several modification techniques have been developed. In this study, a novel magnetic nanocomposite based on the electrostatic interactions between graphene oxide (GO) and copper/iron bimetallic nanoparticles was prepared. In comparison to the previously studied “one pot, in-situ” preparation method of GO based nanocomposites, this co-assembly took advantage of the physical affinity between GO and bimetallic nanoparticles allowing for fine-tuning of the size and dimension of the nanoparticles prior to assembly. The nanocomposite showed a pH dependent assembly behavior that could be used to recycle GO and generate new nanoparticles. At optimal conditions, the novel nanocomposite demonstrated almost complete (~100%) removal of tetracycline (TC) within the first 20 minutes. Nanocomposite showed great performance for pH range of 3 to 8 (above 97%) with nearly complete removal for pH values 5 to 7. Desorption studies exhibited that the nanocomposite not only removed TC but also its transformation products. LC–MS analysis showed that the degradation products were mainly stemmed from TC after the losses of some functional groups from the ring. As well as a high removal efficiency, this nanocomposite showed high stability and easy separation, making it a promising method for treating latent antibiotics in water.