Lotus stalk activated carbon (AC) was produced by ultrasound digestion of lotus stalks in H3PO4. Copper nitrate and iron nitrate were used to impregnate AC, producing Cu(II)-impregnated AC (AC-Cu) and Fe(III)-impregnated AC (AC-Fe). The modified ACs were characterized by N-2 adsorption-desorption isotherms. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption kinetics and isotherms of cephalexin (CEX) in aqueous solution were studied for AC. AC-Cu and AC-Fe. The kinetics and equilibrium data agreed well with the pseudo-second-order kinetics model and Freundlich isotherm model for all three adsorbents. The results also showed that the adsorption capacities of AC-Cu and AC-Fe were larger than the capacity of AC and AC-Fe was found to be the most effective at the removal of CEX in solution. Furthermore, batch experiments were conducted to study the effects of pH (2.5-10.5), initial concentration of CEX (4-16 mg/L), ionic strength (10-1000 mM) on CEX removal. (C) 2010 Elsevier B.V. All rights reserved.