Impedantiometric behavior of solid biopolymer electrolyte elaborated from cassava starch synthesized in different pH

Abstract

This paper approaches the study of pH's effect on elaborate films of solid biopolymer electrolyte from cassava starch and its impedantiometric response. The films of solid biopolymer electrolyte were elaborated by thermochemical synthesis while varying the pH (2, 4, 5, 7, 9, 10, and 12). Starch was extracted from cassava tubers by a traditional method (disintegrated, washed, decanted, filtered, and dried). Solid biopolymer electrolyte films were processed by thermochemical synthesis by adding plasticizers (glycerol, glutaraldehyde, and polyethylene glycol) and lithium salt (lithium perchlorate). The impedance behavior was studied using the electrochemical impedance spectroscopy technique. The Nyquist and Bode's diagrams registered presented a similar trend in all the films; therefore, they were described by the same equivalent circuit model. However, the equivalent circuit components presented different values in each case. The conductivity and capacitance showed a quadratic polynomial tendency in relation to the pH, obtaining the highest conductivity in the films elaborated at acidic pH and the highest capacitance in the films elaborated at basic pH. The degree of basicity or acids allowed conductivity to be modulated or capacitance of the solid biopolymer electrolyte as required. It could be concluded that the production pH has a marked effect on impedantiometric behavior of films of solid biopolymer electrolyte from cassava starch, which may be useful to modulate the electrochemical properties of this type of material in future Applications.