Electrolysis

In chemistry, electrolysis is a process used to generate a non-spontaneous, or controlled, chemical reaction by passing an electrical current through a molten or liquid solution. It is often used to extract individual elements from ionized source materials containing multiple elements. At its most basic level, electrolysis requires three major components: an electrolyte substance that will conduct electricity when added to water or another suitable solvent, a source of direct current (DC) electricity, and a pair of electrodes consisting of an anode with a positive charge and a cathode with a negative charge.

To produce the controlled chemical reaction, current is routed from the DC source through the electrodes into the electrolyte, driving the negatively charged ions in the source material to the anode and the positively charged ions to the cathode through a process known as reduction. This results in the discharge of atoms representing the component elements in the source material, which can subsequently be harvested and used for other purposes.

The First and Second Laws of Electrolysis

Electrolysis is governed by two fundamental laws, which were first described by the scientist Michael Faraday in 1832. They are often referred to as Faraday's laws.

Faraday's first law of electrolysis is that the quantity of elements separated from the source material through the reduction process is directly proportional to the amount of electrical current introduced to the electrolyte solution through the cathodes. He represented this discovery in the formula W ∝ Q, where W equals the mass of the liberated ions and Q equals the quantity of electricity.

Faraday's second law of electrolysis states that if an equal electrical current is introduced to different but connected electrolytes, the masses of the ions discharged at the cathodes will be directly proportional to the equivalent atomic weights of their chemical equivalents. The formula for Faraday's second law can be written as E ∝ Z, where E is the discharged ionic mass and Z is its electrochemical equivalent.

Faraday's laws establish the quantitative relationships between the amount of electricity used in the reaction, ionic mass, and the mass of the generated electrochemical equivalents.

Industrial and Commercial Applications of Electrolysis

One of the earliest applications of electrolysis revolved around the discovery of new elements, as the process could be used to extract atoms that had never before been isolated from source materials. In 1807 and 1808, the English chemist Sir Humphry Davy discovered sodium, potassium, calcium, strontium, barium, magnesium, and lithium using this method. It was subsequently applied to facilitate the discovery of many other elements, some of which have never been observed under any other circumstances.

Today, chemical electrolysis is often used to isolate and manipulate metal elements through a series of processes collectively known as electrometallurgy. The field of electrometallurgy consists of specific techniques that can be used to extract metals from minerals or ores, purify metals, or layer metals on top of one another in the production of industrial materials. One of the most familiar examples of electrometallurgy is the production of nickel-based coins, which actually consist of a small amount of nickel combined with additional alloys to create a final product that will withstand the rigors of circulation.

Electrolysis is also used to mass-produce chemicals and chemical compounds for industrial and commercial use. Chlorine, sodium hydroxide, sodium chlorate, potassium chlorate, and a wide range of fluoride-containing organic materials are all manufactured using various electrolysis processes. Additional applications include the production of hydrogen fuel, the restoration of timeworn metallic objects, and the etching of metal products with identifying information.

Medical Electrolysis

A medical process known as electrolysis is widely used in the cosmetic removal of unwanted body hair, but this technique is actually distinct from chemical electrolysis and is more correctly referred to as electrology. This type of electrolysis achieves the elimination of body hair by applying heat or chemical energy to the hair's root structures, effectively killing the follicle to prevent future hair growth. Existing hair is then removed from the site and will not grow back if the follicle has been fully destroyed. Patients may require multiple treatments to remove hair completely from a particular bodily region before achieving the desired results, especially in the case of male facial hair, which can take dozens of treatments across a period of years to remove permanently. Hair in other areas of the body can typically be removed in a much shorter span of time.

Medical electrolysis is performed with the use of tiny probes, which are inserted through the skin into the opening of the hair follicle. One of three different modalities can then be used to introduce the requisite amount of heat or chemical energy needed to destroy the hair follicle; the three modalities are galvanic electrolysis, thermolysis, and a hybrid or blend of the two. In galvanic electrolysis, the application of electrical energy triggers a controlled chemical reaction that kills the hair follicle. In thermolysis, the hair follicle is killed exclusively with heat. The hybrid or blend technique uses both heat and chemical energy. All three modalities work by permanently neutralizing the parts of the hair follicle that make hair grow and regenerate.

Charles Michel, a St. Louis–based ophthalmologist who successfully used electrical energy to remove ingrown eyelashes from his patients, first developed the electrolysis technique for hair removal in 1875. During the latter decades of the nineteenth century, electrolysis became commercially popular, though early forms of electrolysis equipment were fraught with performance problems and safety risks. During the 1970s and 1980s, major technological advancements led to far more reliable and easy-to-use electrolysis devices, effectively addressing the safety concerns that had been associated with the technique. Today, professionals who offer electrolysis-based hair removal procedures undergo standardized training and accreditation courses to ensure patient safety. Electrolysis remains the only permanent hair removal method to be approved for use by the United States Food and Drug Administration.

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