Nanocomposites of reduced graphene oxide with pure monoclinic-ZrO_2 and pure tetragonal-ZrO_2 for selective adsorptive removal of oxytetracycline

摘要

Oxytetracycline (OTC), as one of widely applied veterinary antibiotic, has become a new environmental pollutant. To explore the feasibility of the nanocomposites of reduced graphene oxide (rGO) with the ZrO2 nanoparticles for OTC removal, two nanocomposites of monoclinic-ZrO2@rGO and tetragonal-ZrO2@rGO through controlling the dosage of triethanolamine are prepared successfully and characterized. Detail investigation of the adsorption for the family of tetracycline antibiotics on the two nanocomposites has been assessed. For comparison, the tetragonal-ZrO2@rGO (198.4 mg g(-1)) exhibits a higher adsorptive amount than the monoclinic-ZrO2@rGO (177.9 mg g(-1)), whereas two nanocomposites demonstrate a remarkably selective uptake of OTC among the family of tetracycline antibiotics due to their higher affinity towards OTC. Adsorption of OTC by in 15 min can reach the equilibrium and is independent on pH in the range of 4-8. The adsorption of OTC by the two nanocomposites is well matched by both pseudo-second order and Langmuir models and exhibits a favorable, endothermic and spontaneous nature. Fourier transform infrared and XRD analysis reveal the interactions between OTC and the nanocomposites such as surface complexation, pi-pi and cation-pi bonding interactions with a crucial role.