A new approach based on the combination of complex impedance and conductivity to investigate the interaction mechanisms of raw polysaccharides in aqueous solutions

Abstract

The molecule-water and molecule–molecule interactions are the main keys to understanding the behavior of polysaccharides in an aqueous solution. In this work, electrical impedance spectroscopy is used to investigate raw polysaccharides' dielectric and electrical properties. Impedance data were carried out for different concentrations in the frequency range [10^-2–10⁶Hz] and then analyzed in Nyquist and bode representation, revealing one clear maximum due to the electrode polarization. Therefore, the complex conductivity is analyzed and makes the other relaxation processes very clear.

Moreover, an appropriate equivalent circuit was developed, showing good agreement with the experimental data. The extrapolation and deconvolution approaches in the frequency range [10^-3–10⁷Hz] were performed to confirm the presence of the three relaxation processes and the validity of the equivalent circuit. The first was attributed to the electrode polarization, and the other processes were attributed to the molecules-water and molecule-counterion interactions. Finally, a clear transition at 5% (w/v) is shown in the evolutions of the conductivity, suggesting the transition from the dilute to the semi-dilute domain.