With High Surface Area Nano-iron Oxide Magnetic Powder Developed

This study, supported by project of national hi-tech plan (No.2001A A2180011),was done on the base of domestic and foreign references about preparation of nanometer magnetic Fe3O4.In order to meet the strict request to the nanometer-medicine target carriers, nanometer Fe3O4 was prepared by microemulsification method and inverse phase method.Nanometer Fe3O4 was prepared by micro-emulsion system ,which was made from n-hexane as oil phase,AEO3+AEO9as the surfactant and Fe2+-Fe3+ and NaOH solution as water phase. The optimum conditions were obtained when n(H2O)/n(AEO3+AEO9) is about 5～20 :1,n(Fe3+)/n(Fe2+) about 1.0 : 1～1.5 : 1,C(Fe3++Fe2+)about0.1～0.2mol#L^-1C(NaOH)0.1⁰.4mol #L^-1,the amount of surfactant (AEO3+AEO9) 15～25% ,aging temperature at 50～80 ℃,aging time 40～60 minutes and pH is over 8.After the reaction, the precipitation was washed by water, alcohol and NH4HCO3 solution in order.In order to reduce the amount of surfactant, a new technique, which was named inverse phase method, was put forward to prepare nanometer Fe3O4 powder. The new method was based on the oil-in-water(O/W) system in the mixture of kerosene, AEO9 +TX10 and Fe2+-Fe3+ and NaOH. The water-in-oil (W/O) can be obtained by heating from oil-in-water (O/W) and nanometer Fe3O4 can be prepared by the micro-reactor. The optimum conditions were as fellows :C(Fe3++Fe2+)0.66 mol·L"1, φ(AEO9+ TX10)4.5%,(p(Fe2++Fe3+)55% and aging temperature 80℃.The crystal type,morphology and particle size, distribution of particle size and specific area surface, purity of the product were characterized by XRD,SEM,LPA,VHB and CA.Results show that the product made from micro-emulsification method was of single crystal type, ball-shape and the purity is over 99%.The distribution is even, the average particle size less than 35nm,the specific surface area more than 80m2 · g-1 and specific saturation magnetization about 65 A · m2 · kg-1.The product made from the inverse phase method was of single crystal type, the purity over 99%.Most of the particles are in ball-shape,only a few in club-shape. The distribution is quite even, average particle size less than 43nm,the specific surface area more than 76m2 ?g-1 and specific saturation magnetization about 43 A ?m2 ?kg-1.