Application of response surface methodology (RSM) for optimization of Cu²⁺, Cd²⁺, Ni²⁺, Pb²⁺, Fe²⁺, and Zn²⁺ removal from aqueous solution using microwaved olive stone activated carbon

BACKGROUND The efficiencies of removal of Cu 2+ , Cd 2+ , Ni 2+ , Pb 2+ , Fe 2+ , and Zn 2+ 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 . RESULTS The optimum conditions obtained were 565 W radiation power, 7 min radiation time, and 1.87 impregnation ratio. This resulted in 98.55% removal of Cu 2+ , 95.32% of Cd 2+ , 98.19% of Ni 2+ 98.83% of Pb 2+ , 99.32% of Fe 2+ , 98.36% of Zn 2+ , 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 1280.71 m 2 g −1 , 0.604 cm 3 g −1 and 4.63 nm, 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 Fe 2+ (62.50 mg g −1 ), followed by Pb 2+ (23.47 mg g −1 ), Cu 2+ (22.73 mg g −1 ), Zn 2+ (15.08 mg g −1 ), Ni 2+ (12.00 mg g −1 ), and Zn 2+ (11.72 mg g −1 ) . CONCLUSIONS OSAC prepared by microwaves can be used for the removal of metals from contaminated wastewater.