Abstract: A series of activated carbon was prepared using almond shell, walnut shell and white apricot shell as raw materials by microwave radiation with H₃PO₄ as activating agent. Activated carbon was carbonized and activated by the nut shell immersed in the mass fraction of H₃PO₄ 40% solution, liquid ratio 1:3. After 24 h of immersion, the microwave with power of 640 W irradiated for 16 min. Pyrolysis mechanism, micromorphology, microstructure, components, nitrogen adsorption-desorption isotherm and pore size distribution of activated carbon were analyzed by TG, XRD, FT-IR, SEM, BET etc. The activated carbon obtained from nut powder by almond shell, walnut shell and white apricot shell have the approximate consistent on the thermal decomposition process and functional groups. They are a typical non-graphitizable. The nut shell of activated carbon has abundant interconnected pores and pore spaces, which size is about 0.4 to 1.2 nm of micropore and 3 to 6 nm of mesopore. It is shown that white apricot shell activated carbon has porous characteristic structure with 981.5 m²/g for specific surface area and 0.570 cm³/g for total pore volume. The adsorption value for methylene blue by white apricot shell activated carbon is 269.6 mg/g, and the iodine value is 1 162.8 mg/g.

Key words: nut shell, activated carbon, pore size distribution, adsorption