Applications of Electrolysis Electroplating Electroforming ElectrorefiningPublished on 24/2/2012 and last updated on Friday 15th of June 2018 at 11:37:03 AM
Applications of Electrolysis
Electrolytic Refining of MetalsThe process of electrolytic refining of metals is used to extract impurities from crude metals. Here in this process, a block of crude metal is used as anode, a diluted salt of that metal is used as electrolyte and plates of that pure metal is used as cathode.
Electrolytic Refining of CopperFor understanding the process of electrolytic refining of metals, we will discuss about an example of electrolytic refining of copper. Copper extracted from its ore, known as blister copper, is 98 to 99 % pure but it can easily be made up to 99.95% pure for electrical application by the process of electrorefining.
In this process of electrolysis, we use a block of impure copper as anode or positive electrode, copper sulfate acidified with sulfuric acid, as electrolyte and pure copper plates coated with graphite, as cathode or negative electrode. The copper sulfate splits into positive copper ion (Cu+ +) and negative sulfate ion (SO4 − −). The positive copper ion (Cu+ +) or cations will move towards negative electrode made of pure copper where it takes electrons from cathode, and becomes Cu atom and is deposited on the graphite surface of the cathode.
On the other hand, the SO4 − − will move towards positive electrode or anode where it will receive electrons from anode and become radical SO4 but as radical SO4 cannot exist alone, it will attack copper of anode and form CuSO4. This CuSO4 will then dissolve and split in the solution as positive copper ion (Cu+ +) and negative sulfate ion (SO4 − −). These positive copper ions (Cu+ +) will then move towards negative electrode where it takes electrons from cathode, and become Cu atoms and are deposited on the graphite surface of the cathode. In this way, the copper of impure crude will be transferred and deposited on the graphite surface of the cathode.
The metallic impurities of anode are also merged with SO4, forming metallic sulfate and dissolve in the electrolyte solution. The impurities like silver and gold, which are not effected by sulfuric acid-copper sulfate solution, will settle down as the anode sludge or mud. At a regular interval of electrolytic refining of copper, the deposited copper is stripped out from the cathode and anode & is replaced by a new block of crude copper. NB :- In the process of electrolytic refining of metals or simply electro refining, the cathode is coated by graphite so that the chemical deposited, can be easily stripped off. This is one of the very common applications of electrolysis.