Removal of antibiotics by adsorption and catalytic ozonation using magnetic activated carbons prepared from Sargassum sp.

Abstract

This study was carried out to determine the best conditions for the preparation of magnetic activated carbons (mACs) from Sargassum sp. as both adsorbents and catalytic supports. Coupling of adsorption and catalytic ozonation for removal and degradation of antibiotics was implemented for several cycles of use in order to assess the efficiency and the stability of these mACs. The mAC prepared by the post-impregnation method (activated carbon with Sargassum sp. + FeCl2.4H2O pyrolyzed at 200 °C for 120 min) showed better adsorption capacity of a mixed solution of antibiotics (95.3, 48.3, 13.4 mg g−1 for tetracycline (Tc), penicillin (Pen) and erythromycin (Ery) respectively after 3 cycles of use) than the mAC prepared by the pre-impregnation method (Sargassum sp. + FeCl2.4H2O pyrolyzed at 664 °C for 65 min). Whereas the evaluation of the degradation under ozone after mAC saturation by adsorption showed a better degradation after 3 cycles of reuse higher than 96 % for Ery, and higher than 99 % for Tc and Pen for the mAC prepared by the pre-impregnation method. Their physicochemical properties were characterized by different techniques, in particular X ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), analysis of the surface acid-base groups by Boehm method, pore analysis and specific surface area measurement (using the Brunauer–Emmett–Teller method) by nitrogen adsorption, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The use of Sargassum sp. is therefore promising for the preparation of efficient bio-sourced mACs for the removal of organic pollutants from polluted waters.