Electroplating, Bioleaching, Phytoextraction and Galvanisation
Electroplating:
● Electroplating is where the surface of one metal is coated with a layer of
a different material.
● The metal used for coating is less reactive than the metal being coated.
● The anode is made from a pure metal used to coat.
● The cathode is the object that is going to be electroplated.
● The electrolyte is an aqueous solution of a soluble salt of the pure metal
at the anode.
● It is used to make metals more resistant to corrosion or damage (E.g.
Chromium plating).
● It is also done to improve the appearance of metals (e.g. Silver-plating
cutlery).
Phytoextraction:
● Relatively new method of extracting metals that rely on biological
processes
● Avoids significant environmental damage
● Very slow and requires electrolysis or displacement to purify extracted
metal.
● Takes advantage of how some plants absorb metals through their roots.
● The plants are grown in areas known to keep metals of interest in the
soil.
● As the plants grow the metals are taken up through the plants vascular
system and become concentrated in specific parts such as their shoots
and leaves.
● These parts are harvested, dried and then burned.
● This ash contains the metal compounds from which the useful metals
can be extracted by displacement or electrolysis reactions.
Bioleaching:
● Technique that uses bacteria to extract metals from metal ores.
● Some bacterial strains are capable of breaking down ores to form acidic
solutions containing metal ions.
● This solution is called Leachate which contains a large amount of metal
ions.
Electroplating:
● Electroplating is where the surface of one metal is coated with a layer of
a different material.
● The metal used for coating is less reactive than the metal being coated.
● The anode is made from a pure metal used to coat.
● The cathode is the object that is going to be electroplated.
● The electrolyte is an aqueous solution of a soluble salt of the pure metal
at the anode.
● It is used to make metals more resistant to corrosion or damage (E.g.
Chromium plating).
● It is also done to improve the appearance of metals (e.g. Silver-plating
cutlery).
Phytoextraction:
● Relatively new method of extracting metals that rely on biological
processes
● Avoids significant environmental damage
● Very slow and requires electrolysis or displacement to purify extracted
metal.
● Takes advantage of how some plants absorb metals through their roots.
● The plants are grown in areas known to keep metals of interest in the
soil.
● As the plants grow the metals are taken up through the plants vascular
system and become concentrated in specific parts such as their shoots
and leaves.
● These parts are harvested, dried and then burned.
● This ash contains the metal compounds from which the useful metals
can be extracted by displacement or electrolysis reactions.
Bioleaching:
● Technique that uses bacteria to extract metals from metal ores.
● Some bacterial strains are capable of breaking down ores to form acidic
solutions containing metal ions.
● This solution is called Leachate which contains a large amount of metal
ions.
