Graphene oxide (GO) nanoparticle is a high potential effective absorbent. Tetracycline (TC) is a broad-spectrum antibiotic produced, indicated for use against many bacterial infections. In the present research, a systematic study of the adsorption and release process of tetracycline on GO was performed by varying pH, sorption time and temperature. The results of our studies showed that tetracycline strongly loads on the GO surface via π–π interaction and cation–π bonding. Investigation of TC adsorption kinetics showed that the equilibrium was reached within 15 min following the pseudo-second-order model with observed rate constants of k2 = 0.2742–0.5362 g/mg min (at different temperatures). The sorption data has interpreted by the Langmuir model with the maximum adsorption of 323 mg/g (298 K). The mean energy of adsorption was determined 1.83 kJ/mol (298 K) based on the Dubinin–Radushkevich (D–R) adsorption isotherm. Moreover, the thermodynamic parameters such as ΔH°, ΔS° and ΔG° values for the adsorption were estimated which indicated the endothermic and spontaneous nature of the sorption process. The electrochemistry approved an ideal reaction for the adsorption under electrodic process. Simulation of GO and TC was done by LAMMPS. Force studies in z direction showed that tetracycline comes close to GO sheet by C8 direction. Then it goes far and turns and again comes close from amine group to the GO sheet.

No abstract

Graphene oxide (GO) sheets were synthesized by modified Hummers method. Microwave hydrothermal reactor (MHR) was applied to reduce graphene oxide. Different temperatures 50 and 180 • C were applied to fabricate four samples with 4, 10, 25 and 60 min exposure times. The deoxygenation of the GO sheets after exposure to MHR was revealed by using UV-visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Raman spectroscopy. Based on XPS analysis, the O/C ratio of the GO sheets decreased from 49 to 17% after exposure to MHR. On the other hand, characterization by TGA illustrated that the O/C ratio of the GO dramatically decreases after exposure of MHR and reached from 37 to 7%. Raman spectroscopy demonstrated that there was no increase in defects' density after reduction. The results confirmed that sample with 180 • C exposure temperature and 60 min exposure time was reduced completely. Therefore this can help to advance using MHR as the green technique of GO reduction.