Fluoroquinolones antibiotics adsorption onto microporous activated carbon from lignocellulosic biomass by microwave pyrolysis

Microwave-assisted KOH activation has been adopted to prepare activated carbon from a lignocellulosic biomass, Albizia lebbeck seed pods. Fluoroquinolones antibiotics such as ciprofloxacin (CIP) and norfloxacin (NOR) were removed from aqueous solutions by adsorption on prepared carbon. The surface area, micropores volume, and mesopores volume of such carbon were 1824.88 m2/g, 0.645 cm3/g and 0.137 cm3/g, respectively. The effects of pH, adsorbent dose, and contact time on the adsorptive removal process were studied. Maximum removal percentages of 96.12% and 98.13% were achieved for CIP and NOR adsorption, respectively. The best fitting for equilibrium adsorption data of both antibiotics was obtained by the Langmuir isotherm with maximum capacities of 131.14 and 166.99 mg/g for CIP and NOR, respectively. The kinetic data were found to follow closely the pseudo-second order model for both antibiotics. Results of thermodynamic studies showed an endothermic CIP adsorption compared to an exothermic NOR adsorption under examined conditions.