Intercalation of tetracycline in nano sheet layered double hydroxide: An insight into UV/VIS spectra analysis

In this study, nanosheet-layered double hydroxide (LDH) was synthesized by hydrolyzing urea and used for adsorption of tetracycline antibiotic from an aqueous solution. The prepared adsorbent was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier-transform infrared (FTIR) spectroscopy. XRD pattern analyses confirmed that the prepared adsorbent had a typical LDH nanostructure. The sorption rate was significantly affected by the solution pH, and higher removal efficiency was observed at pH 3. Under optimal condition, about 82% of tetracycline was removed. UV/VIS spectrum studies demonstrated that nitrate, carbonate, sulfate, and fluoride did not interact with the molecular structure of tetracycline. However, the results showed that all the foreign anions decreased the tetracycline removal efficiency by 7-30%. Four kinetic models were studied and best fitted onto experimental data with higher correlation coefficient for pseudo second-order model. In addition, results of the equilibrium study demonstrated that the removal of tetracycline followed the Freundlich isotherm model and the maximum sorption capacity was found to be 98.04 mg/g. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.