Mechanism of adsorption of tetracycline-Cu multi-pollutants by graphene oxide (GO) and reduced graphene oxide (rGO)

BACKGROUND The adsorption of single pollutants onto graphene oxide (GO), such as heavy metals or organics, has been widely investigated, however, the simultaneous removal of the antibiotic-heavy metal multi-pollutants from the intensive livestock and poultry industry has been investigated little. In this study, the GO/reduced GO(rGO) were prepared as adsorbent and the adsorption performance of tetracycline (TC), Cu2+, and the multi-pollutants TC-Cu were investigated. RESULTS The GO surface was abundant in oxygen-containing functional groups but was affected by a reduction effect, and thus rGO lost a large amount of -OH. In the presence of Cu2+, GO's adsorption quantity of TC increased by 96.64%, which was considerably higher than the increase (23.31%) observed in the case of rGO. In contrast, the adsorptivity of GO/rGO in Cu2+ increased slightly with the addition of TC. Further, X-ray photoelectron spectroscopy (XPS) analysis revealed that the Cu2+ participated in a bridging interaction between TC and the adsorbent, forming a complexation TC-Cu. CONCLUSION GO and rGO showed favorable adsorption of TC, Cu2+, and TC-Cu. The adsorption capacity of multi-pollutants was increased compared with individual adsorption, indicating a cooperative adsorption between the TC and Cu2+. The adsorption mechanism mainly included pi-pi conjugation, electrostatic interactions, and the bridge connection by Cu2+, which contributed to the performance of GO/rGO with respect to the adsorption of the antibiotic-heavy metal multi-pollutants. (c) 2018 Society of Chemical Industry