Conductimetric studies of chitosan in aqueous medium

Summary

Conductimetric studies of two aqueous chitosan salts systems are presented. These salts were prepared dissolving the polyelectrolyte with desionised water and using an excess of the corresponding stoichiometric amount of acid (HCl or HNO₃) and then purified by dialysis. Limit equivalent conductance (Λ^o) was obtained by fitting the experimental conductimetric results to a fifth order polynomial function. This result was employed to determine classical conductimetric parameters in dilution limiting conditions, i.e., charge parameter (ξ), polyelectrolyte equivalent ionic conductivity (λ_p^o), fractional hydrodynamic coefficient (f), etc., employing Kohlrausch law for independent ions migration. We have found a remarkable agreement between experimental and theoretical results when Rinaudo equation was employed to calculate ξ. Additionally, our conductimetric studies show that equilibrium constants are similar for both systems when K values are obtained from plots of Λ²/[Λ^o(Λ^o-Λ)] vs. 1/c_p.