Dielectric analysis of chitosan–iron composite microspheres suspensions: Access to internal and interface electrokinetic information of microspheres

Iron doped chitosan microspheres (IDM) with different concentrations of iron (wt.%) were prepared and dielectric behavior of the IDM suspensions was investigated in the frequency range from 40 Hz to 110 MHz. Dielectric spectra of these suspensions showed distinct relaxations at MHz frequency range which are attributed to the interfacial polarization between IDM particle and medium solution. The relaxation varied with the concentration of iron (wt.%) in IDM and the changing trends of relaxation parameters showed that: an appropriate iron doping concentration can increase adsorption capacity of chitosan, however, when the doping concentration exceeds a certain value, the capacity will be reduced. Furthermore, the phase parameters of the suspensions were calculated by using Hanai method. The obtained permittivity ɛp of IDM demonstrates a significant change with the iron concentration (wt.%). In addition, the interfacial electrokinetic parameters, surface conductivity λ, charge density σ and zeta potential ζ, were also estimated from the phase parameters and these parameters indicate that: the interfacial properties between the IDM and continuous medium were little affected by iron concentration in IDM.