Fabrication of agar-gel microelectrodes and their application in the study of ion transfer across the agar-water 1,2-dichloroethane interface

In this paper, we describe a simple procedure to make agar-gel microelectrodes by filling micropipettes. These microelectrodes were used to study K+ transfer across the agar-water \ 1,2-dichloroethane interface facilitated by dibenzo-18-crown-6 (DB18C6), and the transfer of tetraethylammonium (TEA(+)). The results observed were similar to those obtained at micro-liquid \ liquid interfaces. The effect of various amounts of agar in the aqueous phase was optimized and 3% agar was chosen based on the potential window and solidification time. The different shapes of micro-agar-gel electrodes were prepared in a similar way. The fabricated agar-gel microelectrodes obey the classical micro-disk steady-state current equation, which is different from the behavior of a normal micropipette filled with aqueous solution without silanization. (C) 2001 Elsevier Science B.V. All rights reserved.

Scanning electrochemical microscopy study of electron transfer across the water/1,2-dichloroethane interface induced by common ions

In this work, we report the reverse electron transfer reaction between TCNQ in 1, 2-dichloroethane (DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA(+)) and tetraphenylarsonium ion (TPAs+). The effects of the concentrations of TBA(+) and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(k(i)) were obtained under different values of K-p(K-p=c(i)(w)/c(i)(o)) for both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.

ELECTROCHEMICAL STUDY OF ISOPOLY AND HETEROPOLY ANION TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE .2. VANADIUM-CONTAINING HETEROPOLYTUNGSTATE ANIONS

The electrochemical transfer behaviour of vanadium-containing heteropolytungstate anions [PW12-xVxO40]((3+r)-) (x = 1-4) across the water \nitrobenzene interface has been investigated by cyclic voltammetry and chronopotentiometry with cyclic linear current scanning. The transfer of PW11V1O404-, HPW10V2O404-, H2PW10V2O403-, H3PW9V3O403- and H4PW8V4O(40)(3-) across the water \nitrobenzene interface can be observed within the potential window. The effects were observed of pH in the water phase on the transfer behaviour and the formation of vanadium-containing heteropolytungstate anions in solution. Heteropolytungstate anions become more stable due to their involving the vanadium atom. The degree of protonation and the dissociation constant of the trivalent vanadium-containing heteropolytungstate anion of protonation increase with increasing vanadium content. The transfer processes are diffusion-controlled The standard transfer potential, the standard Gibbs energy and the dissociation constant for vanadium-containing heteropolytungstate anions have been obtained and the transfer mechanisms are discussed.

ELECTROCHEMICAL STUDY OF ISOPOLYMOLYBDATE(VI) ANION TRANSFER ACROSS THE WATER/NITROBENZENE INTERFACE

Isopolymolybdate (VI) anion transfer across the water/nitrobenzene (w/n) interface was studied by cyclic voltammetry. The effect of pH and responsed kinetics of isopolymolybdate anion's formation in the water phase on the transfer behavior have been studi

PREDICTION OF THE GIBBS ENERGY OF ION TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE USING 3 NEW TOPOLOGICAL INDEXES

Correlation analysis of the standard Gibbs energy for a series of tetraalkylammonium ions, protonated substituted ethylenediamine derivatives and protonated aromatic amine derivatives using three new topological indices Ax1, Ax2 and Ax has been studied. T

CYCLIC VOLTAMMETRIC STUDY OF QUININE DERIVATIVES TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE

Quinine derivatives, quinine hydrochloride and 8-hydroxyquinoline, transfer across the water/nitrobenzene interface was studied by cyclic voltammetry. The effect of solution acidity on the transfer behaviour was observed. Transfer mechanism was discussed

ELECTROCHEMISTRY OF THE TRANSFER OF ISOPOLY AND HETEROPOLY ANIONS ACROSS THE WATER NITROBENZENE INTERFACE - ISOPOLYTUNGSTATE AND HETEROPOLYTUNGSTATE ANIONS

The transfer behavior of the heteropoly anion [H3PW11O39]4- and the isopoly anion [H2W12O39]4- across the water/nitrobenzene interface was investigated by cyclic voltammetry and chronopotentiometry with linear current scanning. The transfer processes were

THE TRANSFER OF METAL-IONS ACROSS THE WATER-NITROBENZENE INTERFACE FACILITATED BY NEUTRAL CARRIER ETH-129

The transfer of H+, Li+, Na+, Zn2+, Mg2+ and Cu2+ facilitated by ionophore ETH 129 (N, N, N', N'-tetracyolohexyl-3-oxapentanediamide) across water/nitrobenzene interface has been studied by the cyclic voltammetry. The mechanism of the transfer process has been discussed. The diffusion coefficients and the stability constants of the complexes formed in the nitrobenzene phase have been determined.

VOLTAMMETRIC STUDY OF TRANSFER OF ReO4-, IO4- AND MnO4- ANIONS ACROSS THE WATER/NITROBENZENE INTERFACE

The transfer of ReO4-, IO4- and MnO4- anions across the water/nitrobenzene interface was investigated by cyctic voltammetry with four electrode system. The transfer process of these anions is ascribed to the diffusion-controlled under the experimental conditions, The linear relationship between the peak current and concentration of these anions in aqueous phase can be for analysis and monitoring the chemical reaction between IO4- and N (C2H4OH)(3).

ELECTROCHEMICAL TRANSFER OF 12-SILICOTUNGSTATE ANION ACROSS THE WATER NITROBENZENE INTERFACE

It has been firstly found by means of cyclic voltammetry (CV) and chronopotentiometry with linear current-scanning (CLC)that 12-silicotungstate anion (SiW_(12)O_(40)~(4-)) with high charge numbers, large molecular volume and symmetric structure can cross

HE PHASE TRANSFER OF CO(II) CATALYZED BY 2,2 '-BIPYRIDINE AT THE WATER/NITROBENZENE INTERFACE

The chemical reactions coupled with the phase transfer of Co(Ⅱ) catalyzed by 2,2′ -bipyridine across the water/nitrobenzene interface have been observed by using cyclic voltammetry (CV). Coupled chemical reactions both in the organic phase or in the aqueus phase influence the CV behavior of successive complex phase transfer obviously and an irreversible phenomenon similar to that existed at the metal electrode/electrolyte solution interface was observed. For different complexes, the phase transfer mechanism...