Electrolysis NaCl solution

Explosion Hazards. The electrolysis of aqueous solutions often lead to the formation of gaseous products at both the anode and cathode. Examples are hydrogen and chlorine from electrolysis of NaCl solutions and hydrogen and oxygen from electrolysis of water. The electrode reactions. 

There have been a number of cell designs tested for this reaction. Undivided cells using sodium bromide electrolyte have been tried (see, for example. Ref. 29). These have had electrode shapes for in-ceU propylene absorption into the electrolyte. The chief advantages of the electrochemical route to propylene oxide are elimination of the need for chlorine and lime, as well as avoidance of calcium chloride disposal (see Calcium compounds, calcium CHLORIDE Lime and limestone). An indirect electrochemical approach meeting these same objectives employs the chlorine produced at the anode of a membrane cell for preparing the propylene chlorohydrin external to the electrolysis system. The caustic made at the cathode is used to convert the chlorohydrin to propylene oxide, reforming a NaCl solution which is recycled. Attractive economics are claimed for this combined chlor-alkali electrolysis and propylene oxide manufacture (135). 

The key role of RuOa for the electrochemical stability of Ru02 based DSA electrodes for Cl2 evolution was also pointed out by Augustynski et al. [45] on the basis of XPS data. After electrolysis in NaCl solution Augustynski found Cl species on the surface of the DSA electrode and a higher Ru oxide species, most probably Ru03. 

The electrochemical characterisation studies, discussed in the previous section, showed that a 40 at.% Ru electrode, when subjected to extended electrolysis or potential or current cycling in NaCl solutions and when the chlorine overpotential reaches 300-400mV, behaves like a fresh, low at.% Ru (about 5 at.%) electrode. This strongly suggests that Ru losses from the Ru/Ti oxide coating occur during electrolysis. To determine whether or not the Ru losses in failed anodes take place by uniform dissolution across the entire coating or whether only localised surface... 

Another option to lower the Ru losses is to dope the anode coatings with IrO2, which has been shown [53, 54] to markedly decrease the Ru corrosion rate during electrolysis in NaCl solutions. This would minimise the surface depletion of Ru, as shown by the SIMS analysis of the TiC>2 + RuC>2 + IrCU coatings (Fig. 5.19), and thus extend the operating life of the anodes. 

As in the case of cyclic voltammetry, the electrolysis cell can be built with a thermostatic jacket to carry out measurements at low temperatures. In this case, the apparatus is of an isothermic type (i.e. the compartment containing the reference electrode is also cooled). In this case the most suitable reference electrode is the silver/silver chloride electrode filled by the same solution that will be used to dissolve the electroactive substance. One cannot use the saturated calomel electrode or the aqueous Ag/AgCl electrode because the KC1 (or NaCl) solution would freeze. 

Sonoelectrochemical destruction of dyes has also been investigated. Solutions of the acidic dye Sandolan Yellow have been decolourised by a sonoelectrochemical process in aqueous saline solution using platinum electrodes [42]. The process entails the electrolysis of aqueous NaCl solution which involves the liberation of chlorine at the anode and hydroxide ion at the cathode. The overall cell reaction is ... 

Electrolysis as a means of removing contaminants from water works on the premise that the electrolyzed products generate h5q)ochlorite (Morita et al., 2000 Nakajima et al., 2004 Kiura et al., 2002) in the presence of a low concentration of sodium chloride. Hirose et al. (2005) electrolyzed several antineoplastics, eliminating their biological activity and toxicity. The actual electrolysis was done with a cocktail of antineoplastic compounds in a 0.07 M NaCl solution using two platinum-irridium... 

Chlorine (Cl ) and sodium hydroxide (NaOH) are two important chemicals produced by electrolysis. Chlorine and sodium hydroxide are generally among the top ten chemicals produced annually in the United States. The electrolysis of brine or aqueous NaCl solution is used to produce chlorine, sodium hydroxide, and hydrogen (Figure 14.14). The chloride ion in the brine solution is oxidized at the anode, while water is converted at the cathode according to the following reactions ... 

H2 gas is evolved in the electrolysis of solutions of alkali and alkaline earth metal salts. For example, in the electrolysis of an NaCl solution we would obtain H2 gas,... 

On the other hand, application of alkali metal amalgam permits the slowing down of the reaction of metals with alcohols, which is used in the industrial production of alkali metals alkoxides. Production of NaOR by Mathieson Alkali Works is based, for instance, on the reaction of sodium amalgam (formed as a result of the electrolysis of aqueous NaCl solution with the mercury cathode) with alcohol NaOR ROH is isolated from the solutions. Na residue in the amalgam is hydrolyzed, the obtained mixture is returned to the electrolyz-... 

The fundamental principle of SPE reactors is the coupling of the transport of electrical charges, i.e. an electrical current with a transport of ions (cations or anions), through a SPE membrane due to an externally applied (e.g. electrolysis) or internally generated (e.g. fuel cells) electrical potential gradient. For example, in a chlorine/alkaline SPE reactor (Fig. 13.3), the anode and cathode were separated by a cation-SPE membrane (e.g. Nafion 117) forming two compartments, containing the anolyte (e.g. 25 wt% NaCl solution) and the catholyte (e.g. dilute sodium hydroxide), respectively. 

Fig. 15.1 Temperature influence on the electrolysis product of aqueous NaCl solution...

Finally, a preparation of hydrogen that is of considerable importance is the electrolysis of aqueous NaCl solutions ... 

Chlorine is produced in largest quantity by the electrolysis of NaCl solutions in a process represented by the reaction... 

The electrolysis of brine (concentrated NaCl solution) produces hydrogen at the cathode and chlorine at the anode. Write a net ionic equation for each half-reaction and the total reaction. What other chemical is produced in this commercially important process ... 

Figure 21-3 Electrolysis of aqueous NaCl solution. Although several reactions occur at both the anode and the cathode, the net result is the production of H2(g) and NaOH at the cathode and Cl2(g) at the anode. A few drops of phenolphthalein indicator were added to the solution. The solution turns pink at the cathode, where OH ions are formed.

Janssen, LJ. and Hoogland, J.G. (1970). The electrolysis of an acidic NaCl solution with a graphite anode. III. Mechanism of chlorine evolution. Electrochtm. Acta, 15, 941-51. 

Electric resistance was measured on the membrane which was placed partitioning 3.5 N NaCl solution to its one side and 6.0 N NaOH solution to the other side at 85 °C and the solutions were electrolyzed. The electrolysis was carried out by using a saturated solution of sodium chloride as an anolyte, a titanium lath... 

Figure 3. Relationship between electric resistance of NEOSEPTA-F measured by direct current and concentration of catholyte. Key Q, NEOSEPT A-F C-1000 0, NEOSEPT A-F C-2000. Measurements were made with direct current under the same conditions as the electrolysis of NaCl solution was to be carried out.

Chlorine gas, CI2, is prepared industrially by the electrolysis of molten NaCl (see Section 19.8) or by the chlor-alkali process, the electrolysis of a concentrated aqueous NaCl solution (called brine). Chlor denotes chlorine and alkali denotes an alkali metal, snch as sodium.) Two of the common cells nsed in the chlor-alkali process are the mercnry cell and the diaphragm cell. In both cells the overall reaction is... 

Similar problems arise in connection with the electrolysis of dilute NaCl solutions (seawater). NaOCl produced by electrolysis is used to kill marine life in cooling systems in industrial plants using seawater. Interestingly, amorphous Pd-Ir-P alloys have lower activity in dilute solutions, and Pd-Rh-P samples prove to be more suitable under these conditions (102,103). In order to further increase their activity, surface activation by the Zn deposition-heat treatment-Zn leaching method was used (63). 

Because of overvoltage, electrolysis of NaCl solutions does not yield both of the component elements. Water is easier to reduce than Na", so H2 forms at the cathode, even with an overvoltage of 0.6 V ... 

III. Electrolysis of an NaCl solution saturated with HCl in the electrolytic cell described by Bodenstein and Pohl. The oxygen content of the Clg produced in this manner is 0.01%. 

The use of electrolyzed water is also gaining popularity as a sanitizer in the food industry. The acidic and basic fractions obtained by the electrolysis of dilute NaCl solution are applied on food surfaces to reduce the microbial loads [53]. 

Electrolysis of water consumes too much energy and is consequently too costly to be used commercially to produce H2. However, H2 is produced as a by-product in the electrolysis of brine (NaCl) solutions in the course of commercial CI2 and NaOH manufacture ... 

Alternative 2. Purchase and ship, by pipeline from a nearby plant, chlorine from the electrolysis of NaCl solution. React the chlorine with in-house ethylene to produce the monomer and HCl as a byproduct. 

Sodium hydroxide Electrolysis of NaCl solution Chemicals, pulp and paper, aluminum, textiles, oil refining... 

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