The Response Behavior of PAA–B12C4 Electrode to Li+, Mg2+, and Ca2+ in Some Aprotic Solvents and Its Thermodynamic Application

Abstract

The potentiometric response behavior of an electrode, which consists of a non-plasticized carboxyl-modified polyacrylamide polymer (PAA) coupled to benzo-12-crown-4 (PAA–B12C4) to Li+, Mg2+, and Ca2+ in such aprotic solvents as acetonitrile (AN), propylene carbonate (PC), and γ-butyrolactone (GBL), were examined. The electrode showed a Nernstian response to Li+ and Ca2+ in AN, and Li+, Mg2+, and Ca2+ in PC and a near-Nernstian response to Mg2+ in GBL. From the response to Ca2+ it could be confirmed that the membrane potential was mainly established at the polymer membrane–solution interface. The electrode was applied to a study of their complexing with such other basic aprotic solvent molecules (D) as N,N-dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoric triamide. The successive complex formation constants (βi) and Gibbs energies of transfer (ΔGtr(j)) of Li+ in AN and Mg2+ in PC in relation to such D were obtained.

Electrochemical characterization of poly(acrylamide) membrane coated on a gold disk electrode in acetonitrile

“…A number of cation [8,9] and anion [10] selective electrodes and biosensors [11] were developed at our laboratory using a non-plasticized hydrophilic poly(acrylamide) (PAA) as membrane matrix for use in dipolar aprotic solvents and in the study of the thermodynamic properties of ions. Studies of the response mechanisms of the electrodes were also carried out by voltammetry and spectrophotometry [12,13].…”

Development and Application of Ion-Selective Electrodes in Nonaqueous Solutions

“…Table 1. 30 Generally speaking, the PAA-[B12C4] electrode should respond in a Nernstian way to both Li + and Mg…”

“…The constant of ion, bi in a reference solvent, R, was defined in the same way in previous papers. [30][31][32] The emf change, DE, which was the potential difference between the initial and steady potentials obtained at each addition of a quite small volume of other solvents, D, was analyzed by a method proposed by Cox et al 45 Here, it should be noted that the electrode potential, DE, used for obtaining constants is the value of the net potential change due to activity change caused by proceeding chemical reactions.…”

Development and application of poly(acrylamide) membrane ion-selective electrodes for use in dipolar aprotic solutions

“…The carboxyl-modified FAA was used to conjugate with various host compounds (Host), which are able to reversibly react with the interest ions in nonaqueous solutions, to produce host compound modified PAA. The typical host compounds used in our research are shown in Table 1 [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”