Particle size distribution magnetite particles

Chem. Geol. 157 275-284 Meisel.W. (1989) Corrosion processes and their inhibition as studied by Mdssbauer conversion and other electron spectroscopies. Hy-perfine Interactions 45 73-90 Meisen, U. Kathrein, H. (2000) The influence of particle size, shape and particle size distribution on properties of magnetites for the production of toners. J. Imag. Sci. Techn. 44 508-513... 

Considerable effort has been made in the examination of the deposition of oxides of iron onto surfaces, since this has considerable relevance to the operation of boiler plant. Williamson [1990] has reviewed some experimental magnetite (FejOJ deposition data. He draws attention to the wide discrepancies in the results even for similar systems as may be seen from examination of Table 7.3. He attributes the discrepancies to inadequate control of one or more of the less obvious variables in the system such as the water chemistry (even deionised water is likely to "pick up" COj from the atmosphere with an effect on the pH). A fixed particle size distribution is extremely difficult to maintain in an experimental system due to potential agglomeration and is likely to be time dependent. Even particle concentration may not be uniform due to settlement in the parts of the equipment where velocities are low. Experimentally the consistency of these variables are difficult to determine. 

Ferrimagnetic nanoparticles of magnetite (Fc304) in diamagnetic matrices have been studied. Nanoparticles have been obtained by alkaline precipitation of the mixture of Fe(II) and F(III) salts in a water medium [10]. Concentration of nanoparticles was 50 mg/ml (1 vol.%). The particles were stabilized by phosphate-citrate buffer (pH = 4.0) (method of electrostatic stabilization). Nanoparticle sizes have been determined by photon correlation spectrometry. Measurements were carried out at real time correlator (Photocor-SP). The viscosity of ferrofluids was 1.01 cP, and average diffusion coefficient of nanoparticles was 2.5 10 cm /s. The size distribution of nanoparticles was found to be log-normal with mean diameter of nanoparticles 17 nm and standard deviation 11 nm. 

TABLE 3-1 Size [(d (average) d (standard deviation)], Size Distribution (Ad/d). Saturation Magnetization (Af,), and Residual Magnetization (Mr) for Magnetite Particles at Various Temperatures... 

Fig. 2 Size distribution of the magnetite particles in the magnetite sol M(r) is mass fraction of particles of diameter r [76]...

Figure 2 shows the size distribution of a representative sample. In this case the average diameter of the magnetite particles was found to be 4 nm. 

A DMS cyclone cut point ( 50 is greater than the density of the medium and is closely related to the density of the cyclone underflow. The size distribution of the magnetite particles is very important for dense-medium cyclones, and magnetite that is 90% below 325 mesh (45 /xm) was... 

Size distribution of magnetite particles (Fis given in arbitrary units, d is particle diameter, nm). 

Fig. 5. Comparison of magnetite particle sizes and their distribution obtained by common coprecipitation ( ), coprecipitation with fast injection (A) and coprecipitation with reflux and aging ( )...

---