Characteristics of PD-sensors based on hybrid perfluorinated membranes in aqueous solutions of inorganic electrolytes and lysine

The characteristics of PD-sensors based on MF-4SC perfluorosulfonic cation-exchange membranes, particularly those containing surface-functionalized silica nanoparticles, in HCl, NaCl, KCl, CaCl2, and lysine monohydrochloride solutions have been studied. It has been revealed that the degree of hydration of inorganic cations has a dominant effect on the magnitude of PD-sensor response in individual electrolyte solutions. It has been shown that the response and sensitivity of PD-sensors based on hybrid materials with respect to lysine cations increase with increasing concentration of amino groups grafted to SiO2. This feature is attributed to an increase in the counterion concentration in the film owing to a decrease in the water uptake and enhancement of the interaction between the counterions and the functional groups (sulfo groups of membrane, amino groups of dopant) in membrane.