Mesoporous Fe₂O₃ nanoparticles were synthesized using dodecyl amine as a template and ammonia as a precipitant. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption-desorption analysis methods were used to characterize the crystallinity, morphology and the specific surface area. According to the experimental data of acid base titration of mesoporous α-Fe₂O₃ suspension, using FITEQL software and Constant Capacitance Model (CCM), the protonation and deprotonation constants of mesoporous α-Fe₂O₃ were determined. Base on the acid-base constants the adsorption of heavy metal ions (Cu^2＋, Pb^2＋, Zn^2＋) at the surfaces of mesoporous Fe₂O₃ was studied as a function of pH. The surface complexation constants of Cu^2＋, Pb^2＋, Zn^2＋at the surfaces were determined using WinSGW software and the reaction mechanism was discussed as well.

Key words: mesoporous iron oxides, heavy metal ions, acid-base property, surface complexation