What Is an Electrolytic Process?

Electrolysis is the process of passing a current through an electrolytic solution or a molten electrolyte (also called electrolyte) to cause a redox reaction on the cathode and anode. An electrochemical cell can undergo an electrolytic process when a DC voltage is applied.

Caused by the flow of electricity through matter

Take the electrolysis of copper chloride (CuCl ₂ ) solution as an example:

CuCl ₂ is

Anion: S ^2- > I-> Br-> cl-> OH-> SO ₄ ^2- > F-

Cations: Ag ⁺ > Hg ²⁺ > Fe ³⁺ > Cu ²⁺ > H ⁺ > Pb ²⁺ > Sn ²⁺ > Fe ²⁺ > Zn ²⁺ > Al ³⁺ > Mg ²⁺ > Na ⁺ > Ca ²⁺ > K ⁺

Note: Aluminum ions, magnesium ions, sodium ions, calcium ions, and potassium ions have far less electron-taking abilities than hydrogen ions, so these ions cannot be precipitated at the electrode (cathode) under aqueous conditions; but they can be discharged in the molten state . Trivalent iron ions get electrons on the cathode to generate ferrous ions instead of iron. ^[2]

Electrolytic method

Electrolysis is widely used in the metallurgical industry, such as the extraction of metals from ore or compounds (

The main criterion for judging the pros and cons of the electrolytic process is the power consumption per unit product, which depends on the current efficiency and voltage efficiency of the electrolytic process.

Electrolytic current efficiency

The ratio of theoretical power consumption to actual power consumption per unit product. The theoretical power consumption can be calculated using Faraday's law:

This formula shows that the mass q of the substance precipitated during electrolysis is directly proportional to the atomic weight m of the precipitated substance, the current intensity I, and the electrolysis time t , and is inversely proportional to the number of electrons n lost and the Faraday constant F during electrolysis. Under normal circumstances, the current efficiency is relatively high.

Electrolytic voltage efficiency

The ratio of the theoretical electrolytic voltage to the actual electrolytic voltage of the electrolyte during electrolysis. The latter is the cell voltage of the electrolytic cell. The tank voltage is the sum of the theoretical electrolytic voltage, overvoltage, and voltage loss of the transmission conductor. There are many factors that affect the size of the tank voltage. In addition to the aforementioned factors that affect the overvoltage, there are also the contact voltage between the wire and the electrode, the diaphragm material, the structure of the electrolytic cell, and the current density. The cell voltage is usually much higher than the theoretical electrolytic voltage, resulting in low voltage efficiency. Therefore, reducing the overvoltage and the voltage loss of the transmission conductor is the key to improving the voltage efficiency. For many years, people have conducted various researches on this issue, and continuously improved the structure of the electrolytic cell and the electrode materials. Research on electrode materials has focused on the choice of electrode materials. In the anode, graphite electrodes have been developed into titanium electrodes, titanium platinum iridium electrodes, titanium ruthenium electrodes, and other non-ruthenium electrodes. In addition, manganese dioxide electrodes and lead dioxide electrodes have been developed for many special applications. On the cathode side, iron cathodes have evolved into porous cathodes. In recent years, a new type of oxygen electrode process has been developed to apply the principle of fuel cells to the electrolytic industry. No matter it is the cathode or the anode, there is a tendency to apply an active material on the surface of the electrode substrate. The purpose is to make the electrode have a catalytic effect (called the electrocatalytic method), and to reduce the tank voltage to achieve the purpose of saving electricity.