Comparative study on simultaneous adsorption of oxytetracycline and copper (II) by TiO2 nanoparticles and graphene oxide: Implications for environmental behavior

With the development of the nanotechnology industry, the possible coexistence of engineering nanoparticles with organic and heavy metal pollutants in aquatic systems has become a hot issue. However, how different nanoparticles affect the environmental behavior of oxytetracycline (OTC) − copper (Cu 2+ ) complex pollution remains unclear. In this study, we investigated the complex adsorption behavior of nano-TiO 2 and graphene oxide (GO) to OTC and Cu 2+ in water, and the differences of adsorption mechanism are discussed with characteristics analyses. When OTC and Cu 2+ coexist, Cu 2+ formed complexes with OTC, consuming oxygen-containing functional groups of OTC and reducing its adsorption on both nanoparticles. OTC does not affect Cu 2+ adsorption on nano-TiO 2 , but promotes Cu 2+ adsorption on GO. The OTC adsorption on nano-TiO 2 was primarily driven by hydrogen bonding and electrostatic attraction, leaving it with potential mobility. In contrast, the adsorption of OTC on GO was mainly through electrostatic attraction, π-π complexation and hydrogen bonding, and OTC reduced GO to rGO. These strong interactions stabilized OTC on GO surface, reducing its environmental mobility. The results of the research are of great environmental significance for exploring the impact of engineered nanoparticles discharged from industrial production in water on the combined pollution of OTC and Cu 2+ .