Abstract:

γ-Fe₂O₃ nanoparticles were prepared by a solid phase method using ferric nitrate[Fe（NO₃）₃·9H₂O] and dodecyl trimethylammonium bromide（DTAB） as raw materials.The sample was characterized by X-ray diffraction（XRD）,N₂ adsorp-tion-desorption（BET） and vibrating-sample magnetometer（VSM）,and its adsorption ability for direct acid-resistant red 4BS was also studied.The results showed that the prepared γ-Fe₂O₃ sample was γ-Fe₂O₃ nanoparticles with an average crystallite size of 18.5 nm,a specific surface area of 83.2 m ²/g,the pore volume was 0.25 cm ³/g and the most probable pore size was 3.8 nm which belonged to the mesoporous range.The maximum saturation magnetization（Ms） of γ-Fe₂O₃ was 63.7 A·m ²/kg. The adsorption process of mesoporous γ-Fe₂O₃ on direct acid-resistant red 4BS conformed to the quasi-secondary adsorption kinetics model.The adsorption process of γ-Fe₂O₃ on direct acid-resistant red 4BS also fitted well with Langmuir isotherm mo-del and its maximum adsorption capacity was estimated to be 113.3 mg/g,and the γ-Fe₂O₃ nanoparticles could be reusable.

Key words: mesoporous γ-Fe₂O₃, adsorbent, magnetic separation, direct acid-resistant red 4BS