Adsorption of amoxicillin onto high surface area-activated carbons based on olive biomass: kinetic and equilibrium...

This study presents the extraction of antibiotic amoxicillin (AMX) from aqueous solution employing activated carbons (AC) from olive biomass (OB). Two AC were prepared using ZnCl₂ (activator agent), and a conventional muffle furnace (ACF) or microwave oven (ACMW). The structure, morphology, and textural properties from both AC were analyzed by scanning electron microscope (SEM), pH of point-zero-charge (pH_PZC), infrared spectroscopy (FTIR), and N₂ adsorption/desorption isotherms. AC with mesoporous structures rich in oxygenated groups and high specific area (as high as 1742 m² g^-1) were helpful for the efficient and fast adsorption of AMX. The Avrami kinetic nonlinear equation showed the best fitting for the empirical data when related to the pseudo-1st and pseudo-2nd order. The isothermal experimental data followed the Liu nonlinear model, displaying at 25 °C the maximum sorption capacity of 237.02 and 166.96 mg g^-1 for the ACF and ACMW, respectively. An adsorption test with synthetic hospital effluent was carried out to evaluate the possibility of applying both adsorbents in wastewater purification. The purification efficiency was up to 94.4% and 91.96% for ACF and ACMW, respectively. Therefore, the AC obtained from OB (containing a mixture of seed, pulp, and olive peel) has a high potential for application in removing emerging contaminants from the wastewater.