Adsorptive removal of tetracycline antibiotic onto magnetic graphene oxide nanocomposite modified with polyvinylpyrroilidone

Disposal of pharmaceutical compounds in wastewaters poses potential environmental risk, especially to aquatic life. Herein, magnetic CuFe2O4-graphene oxide (GO) modified with polyvinylpyrrolidone (PVP) ternary nanocomposite (PMGO) was prepared, by a simple ultrasonic method, and successfully applied to the removal of tetracycline (TC) as a model pharmaceutical species. The defect sites of graphene oxide layers served as nucleation centers that allowed the anchoring of both PVP and CuFe2O4 nanoparticles, resulting in reduced agglomeration chances of GO sheets and thus enhanced its TC removal efficiency. Furthermore, the synthesized PMGO was characterized using SEM-EDS, HRTEM, XRD, XPS, FTIR, BET, and VSM. The removal including was optimized by examining the effects of operating parameters, including, initial TC concentration, solution pH, contact time, and PMGO mass. Adsorption isotherms were examined using three-parameters (Hills and Sips) and two-parameters (Langmuir, Freundlich and Tekman) models. PMGO exhibited a maximum adsorption capacity of 193.8 mg/g according to Sips model that exhibited the best fit to experimental data. Moreover, TC removal fitted the PSO kinetics. The removal mechanism was inferred based on adsorption isotherms and kinetic investigations, as well as changes of medium pH and spectral analysis of PMGO composite after adsorption and revealed that electrostatic attraction, 7C-7C interaction, and H-bonding were essential contributing forces, where a TC monolayer was adsorbed onto the PMGO surface and OH  and H+ exerted competitive effects. Importantly, the synthesized nanocomposite exhibited outstanding performance even in the presence of coexisting species (NaCl and SDS surfactant), as well as excellent reusability for practical applications.

Automated summary

In this study, a magnetic CuFe2O4-graphene oxide (GO) modified with polyvinylpyrrolidone (PVP) ternary nanocomposite (PMGO) was prepared and successfully used for the removal of tetracycline (TC) as a representative pharmaceutical compound. The defect sites of GO layers served as nucleation centers for PVP and CuFe2O4 nanoparticles, improving the TC removal efficiency. The PMGO showed excellent performance in the presence of coexisting species and can be reused for practical applications.