Two-compartment electrochemical cell

In the OFR technique, the OFR is measured continuously in the anodic compartment during constant current (galvanostatic) electrolysis in a two-compartment electrochemical cell. The instantaneous current efficiency (ICE0fr) is then calculated using the relation ... 

The electrochemical 2-chlorophenol and 2,6-dichlorophenol removal from aqueous solutions using porous carbon felt (Polcaro and Palmas 1997) or a fixed bed of carbon pellets (Polcaro et al. 2000) as three-dimensional electrodes was investigated by Polcaro s group. The group s experimental setup consisted of a two-compartment electrochemical cell separated by an anionic membrane where the carbon felt or pellets could be lodged and the solution was recirculated by peristaltic pumps. Both carbon-based anodes effectively removed the chlorophenols as well as their reaction... 

A two-compartment electrochemical cell contains NaCl in one compartment and KCl in the other. The compartments are separated by a porous partition. Concentrations of both the electrolytes are equal. If /l,3ciand are the equivalent conductivities of the two solutions, show that the liquid junction potential is given by... 

An electrochemical microflow reactor, which is composed of diflone and stainless steel bodies produced by a mechanical manufacturing technique, is shown in Figure 7.24. The reactor consists of a two-compartment electrochemical cell, which is divided by a PTFE membrane. Carbon felt (7 mm x 7 mm x 5 mm) made of carbon fibers = 10 im) is used as the electrode. 

Catalysts were characterised by cyclic voltammetry using a two compartment electrochemical cell. The working electrode consisted of a Pt-mesh basket containing... 

To study these phenomena, one measures the hydrogen permeability of a metal as a function of chosen variables using a two-compartment electrochemical cell schematically shown in Figure 11.30. The working electrode, in the form of a thin sheet, separates the two electrolyte compartments. In the cell s left-hand compartment, the electrode acts as a cathode. When a small, constant current is applied, the protons are reduced to hydrogen. A fraction of this hydrogen dissolves in the metal and diffuses across the thin sheet. 

Figure 11.30 Two-compartment electrochemical cell used for the measurement of the hydrogen permeability of metals (schematic).

In the metal the atomic hydrogen diffuses towards the zone of maximum plastic deformation, in front of the crack tip. The solubility reaches particularly elevated values at this location because of the high defect concentration (mainly dislocations). The diffusion rate depends on the difference in hydrogen concentration between the surface and the zone of maximum stress, and on the value of the diffusion coefficient. It can be studied using the two compartment electrochemical cell of Figure 11.30 by varying the thickness of the metal sheet electrode, all other parameters being kept constant. 

A two-compartment electrochemical cell is used to measure the diffusion coefficient of hydrogen in iron. The solubility of hydrogen in the metal under the conditions of the experiment is equal to 1.62 cm (25 °C, 1 bar) per gram of Fe. At the anode, a current density of 80 /tA cm is measured, which is attributed to the oxidation of hydrogen. The thickness of the iron sheet is 20 jim. Calculate the diffusion coefficient of hydrogen in iron. 

The electrochemical behavior of malonyl-a-aminopyridines 661 was investigated by Gullu et al. in acetonitrile or a mixture of trifluoroacetic acid and dichloromethane containing tetrabutylammonium tetrafluoro-borate or triethylammonium trifluoroacetate in a water-jacketed, two-compartment glass cell equipped with a platinum disk anode at 1.50 V (Ag/ Ag+) and a carbon-rod secondary electrode (91T675). Controlled potential anodic oxidation of 661 afforded labile coupled carboxylic acids 662 (R2 = COOH), which easily decarboxylated to compounds 662 (R2 = H) under the work-up conditions. Sometimes, the carboxylic acid 662 (R2 = COOH) could be isolated or when the reaction mixture was treated with methanol, methyl ester 662 (R = H, R1 = Bu, R2 = COOMe) was obtained in 40% yield. 

Fig. 1.5 Schematic view of the two-compartment electrochemical flow cell. R reservoirs, P pumps, E electrochemical cell with membrane, W heat exchangers, F gas flow controllers...

Fig. 6 Sketch of a three-compartment electrochemical cell, employing two monovalent ion-exchange membranes, used to split the concentrated salt solution MX (where M can be sodium and X can be sulfate, for example). Operating under optimum conditions, the cell arrangement will generate pure concentrated base in the cathode compartment and the corresponding acid in the anode compartment. (The illustration is taken from p. 14 of Ref. 124).

The electrolyte solution used to grow the graft copolymer in a one-compartment electrochemical cell with two platinum electrodes contains 0.1 M tetra-butylammonium tetrafluorborate, 0.1 M pyrrole, and different amounts of random copolymer with 6% possible grafting sites in dichloromethane. The conductivity of films grown at a current density of 0.1 mA cm depends on the ratio of pyrrole to linear copolymer. For example, the conductivity of films grown from a 1 1 mixture is 5 x 10 S cm and the conductivity of films grown from a 6 1 (pyrrole/linear copolymer) molar mixture is 0.4 S cm". Both products are 100% insoluble in methylene chloride, indicating that polystyrene is chemically incorporated. 

With eveiy change in ion concentration, there is an electrical effect generated by an electrochemical cell. The anion membrane shown in the middle has three cells associated with it, two caused by the concentration differences in the boundaiy layers, and one resulting from the concentration difference across the membrane. In addition, there are ohmic resistances for each step, resulting from the E/I resistance through the solution, boundary layers, and the membrane. In solution, current is carried by ions, and their movement produces a fric tion effect manifested as a resistance. In practical applications, I R losses are more important than the power required to move ions to a compartment wim a higher concentration. 

An electrochemical cell in which electrolysis takes place is called an electrolytic cell. The arrangement of components in electrolytic cells is different from that in galvanic cells. Typically, the two electrodes share the same compartment, there is only one electrolyte, and concentrations and pressures are far front standard. As in all electrochemical cells, the current is carried through the electrolyte by the ions present. For example, when copper metal is refined electrolytically, the anode is impure copper, the cathode is pure copper, and the electrolyte is an aqueous solution of CuS04. As the Cu2f ions in solution are reduced and deposited as Cu atoms at the cathode, more Cu2+ ions migrate toward the cathode to take their place, and in turn their concentration is restored by Cu2+ produced by oxidation of copper metal at the anode. 

Figure 4.30 Electrochemical micro reactor, a diaphragm micro flow cell, applied to perform the cation flow method. Assembled device (left). Disassembled device showing the two compartments of the cell within the housings and the diaphragm (right) [67. ...

This type of electrochemical reactor is composed of two bodies by mechanical manufacturing [66, 67]. It contains a two-compartment cell with an anodic and cathodic chamber separated by a membrane as diaphragm. The anodic chamber is equipped with a carbon felt anode made of carbon fibers a platinum wire is inserted in the cathodic chamber (Figure 4.30). 

The principal evidence in favor of the electrochemical mechanism is the observation that metal deposition can occur, albeit at a much reduced rate, in a two-compartment cell. When one of the compartments contains only the metal ions and the other only the sodium hypophosphite, metal deposition occurs on the electrode in the first compartment, being driven by hypophosphite oxidation at the electrode in the other half-cell [36, 37],... 

An electrochemical cell was constructed by connecting the copper wire attached at the back of the Ti02 electrode to the platinum black cathode through a load. The two compartments were connected through an agar salt bridge that allows the exchange of ionic... 

The solution used for all experimentation was 5 M NaCl, made up using triply distilled water. Electrolysis experiments were carried out in a one-compartment cell at either room temperature or at 90°C. All electrochemical experiments were carried out using a two-compartment cell, with the RE compartment connected to the WE and CE compartments via a Luggin capillary. 

Platinum chemically deposited on a Nafion membrane was used as a platinum SPE (Solid Polymer Electrolyte) electrode. The electrochemical measurements were performed using the half cell shown in Fig. 2-2. The cell body is made from Teflon (PTFE). The cell is divided into two compartments one for backside gas supply one for the electrolyte. SPE electrodes are placed between them with the deposited side facing the gas compartment. A gold foil with a hole was placed behind the SPE electrode... 

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