Palladium was discovered and entered into the periodic table in 1803.
At the end of the 18th and beginning of the 19th century, there were many discoveries in the scientific world. Chemistry is no exception.
The raw material for the vessels was crude metal, in which there were impurities of gold and mercury. Once again, while purifying the material and dissolving the metal in aqua regia, Wollaston discovered a clot of noble silver color. The idea that this might be an element unknown to science prompted him to continue researching this metal. A year later, after many experiments and reactions, a full-fledged ingot of precious palladium was isolated.
The origin of the noble name
William Wollaston named the metal after the newly discovered asteroid Pallas. This celestial body was discovered a year before the discovery of the precious metal in 1802 by the German astronomer Olbers.
The astronomer named the new celestial body in honor of the legendary wooden image of Pallas Athena. According to ancient Greek mythology, after the theft of Pallas by Odysseus and Diomedes, Troy fell.
Being in nature. Rarity is its virtue
One of the rarest elements on planet Earth. It belongs to the group of platinum metals, most of it is concentrated in the center of the planet’s core.
It occurs naturally in nature as allopalladium. But this is rare. The noble metal is often found in the form of alloys with other elements. There are about 30 such possible connections.
Palladium is a transition metal. Under normal conditions, it forms silvery-white crystals with a cubic system, space group Fm3m, cell parameters a = 0.38902 nm, Z = 4, structural type of copper.
Pure metal is ductile. Cobalt, nickel and rhodium are added to increase hardness. Palladium does not dissolve in water.
The melting point is 1554 °C. Boiling point around 2940 °C. The heat of fusion is 16.7 kJ/mol. The heat of vaporization is 353 kJ/mol.
The metal actively absorbs hydrogen, forming solid solutions.
Precious palladium is the most reactive of the platinum metals. Does not react with water, dilute acids, alkalis, ammonia solution. Reacts with hot concentrated sulfuric and nitric acids, unlike other platinum metals. Can be brought into solution by anodic dissolution in hydrochloric acid.
At room temperature, it reacts with aqua regia, wet chlorine and bromine. When heated, it reacts with fluorine, sulfur, selenium, tellurium, arsenic and silicon. It oxidizes when fused with potassium hydrosulfate, and also interacts with a melt of sodium peroxide.
Natural palladium has six stable isotopes. The longest-lived artificial radioactive isotope is 107Pd (T1/2 7 106 years).
Some isotopes of palladium are actively formed as fission fragments of uranium and plutonium; Thus, the irradiated fuel of modern reactors with a burnup of 3% contains 0.15% palladium.
Platinum group metal production method
The precious metal of the platinum group is obtained by processing nickel, silver and copper sulfide ores. Part of the palladium is obtained by recycling secondary raw materials. This is approximately 10% of the total metal.
Getting palladium from aqua regia has not changed since its discovery. Precious metals are precipitated, palladium powder is obtained, which is then remelted and reduced. From palladium salts, palladium black is obtained – a finely crystalline powder of palladium.
Also, the precious metal can be obtained by electrodeposition from nitrite and phosphate acid electrolytes.
Metal as catalyst
The use of platinum metal as a catalyst is undeniable – they are widely used in the oil refining industry for oil cracking. Palladium is also used to hydrogenate fats. The irreplaceable benefit of palladium chloride in the form of a catalyst is manifested as the detection of micron amounts of carbon monoxide in air or gas mixtures.
Palladium membranes are used for deep purification of hydrogen. This is due to the fact that hydrogen diffuses well under the influence of this metal alloy.
The use of palladium in industry is quite wide. One of the main directions in this area is electroplating. An alloy of palladium chloride is used as an activating agent in the galvanic plating of dielectrics. The metal is capable of depositing copper on the surface of laminates in the production of printed circuit boards in electronics.
Due to its properties, the field of application of palladium in the electronics industry is much wider than that of silver and other precious metals. Metal and alloys based on it are used as coatings, which must be resistant to sulfides.
The widespread use of palladium is also indicated by the areas of radio communications, broadcasting, and television. The noble alloy is used in the production of reochords, which are used in military and aerospace technology.
In jewelry and coinage
Gold changes its color from yellow to noble silver thanks to the platinum group metal. Even 1% palladium can change the shade of gold. It is he who acts as the main component in jewelry made of “white” gold.
Also, coins of limited editions and circulations are produced from an alloy of palladium and silver.
Palladium in medicine – it can heal
The applications of the noble metal and alloys based on it in medicine are very wide. Palladium is used in the manufacture of medical instruments. It is also used in the manufacture of dentures and implants. In small doses, the metal is even used to treat cancer.
Other applications of palladium
- The properties of palladium highlight a wide range of applications. This metal has found its necessity in the production of utensils and metal parts, which must be resistant to corrosion.
- It is widely used as one of the elements in the melting of distillation pipes, vessels, pump parts.
- Palladium prevents sparking on electrical contacts during welding.
Indicators of production and consumption
The largest deposits of the precious metal in nature are located in the Russian Federation (Norilsk and Talnakh). Mining of palladium in these places has been established since the discovery of the element. Small deposits are found in South Africa (Transvaal), USA (Alaska), Canada and Colombia.
Over the past year, palladium mining in the world has reached 270 tons. Russia remains the world leader in the production and supply of metal. On average, about 150 tons are mined there annually. South Africa ranks second, and metal production in this country reaches 85 tons per year. America and other countries are far behind these indicators.