BACKGROUNDThe efficiencies of removal of Cu2+, Cd2+, Ni2+, Pb2+, Fe2+, and Zn2+ from aqueous solution with olive stone activated carbon (OSAC) were investigated in this work. A central composite design (CCD) method was used to optimize the preparation of OSAC using microwave assisted potassium hydroxide. RESULTSThe optimum conditions obtained were 565W radiation power, 7min radiation time, and 1.87 impregnation ratio. This resulted in 98.55% removal of Cu2+, 95.32% of Cd2+, 98.19% of Ni2+ 98.83% of Pb2+, 99.32% of Fe2+, 98.36% of Zn2+, and 85.15% of OSAC yield. The surface characteristics of the AC prepared under optimized conditions were examined by pore structure analysis, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The BET surface area, total pore volume and average pore diameter of the prepared AC were 1280.71m(2)g(-1), 0.604cm(3)g(-1) and 4.63nm, respectively. The equilibrium data of the adsorption was well fitted to the Langmuir equation and the highest value of adsorption capacity (Q) on the OSAC was found for Fe2+ (62.50mgg(-1)), followed by Pb2+ (23.47mgg(-1)), Cu2+ (22.73mgg(-1)), Zn2+ (15.08mgg(-1)), Ni2+ (12.00mgg(-1)), and Zn2+ (11.72mgg(-1)). CONCLUSIONSOSAC prepared by microwaves can be used for the removal of metals from contaminated wastewater. (c) 2013 Society of Chemical Industry