Cerium is a metal in grey and shimmering radiant. The symbol of Cerium is Ce in the periodic table and the atomic number is 58. It is one most abundant element of the rare earth elements and the 2nd most active lanthanide after europium and 25th most-abundant element with approx 0.0046% of Earth’s crust weight. It is soft but a little harder than lead. It is found in lanthanides. It contains 82 neutrons and 58 protons and 58 electrons. It is radioactive in nature as its number of neutrons is greater than the number of protons.
Cerium is found in allanite, monazite, bastnaesite, and other minerals also. For commercial purposes, it is prepared by the reduction of the fused fluoride with calcium.
Analytical techniques such as atomic absorption or emission spectrophotometry are used for the determination of cerium. Some of the other techniques are ICP-AES, stripping voltammetry, and involve high cost.
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Cerium has been discovered in the year 1803 by Jons Jacob Berzelius and Wilhelm Hisinger.
Malleable - can be shaped accordingly by beating with a hammer or by the pressure.
Ductile - can be drawn out into wire.
Ignite – Burn if it is scratched with a sharp object.
Highly reactive with bases, acids, hydrogen gas, and other metals.
Oxidizes slowly in cold water and quickly in hot water.
It is slightly harder than lead and is iron-grey in colour.
It is highly reactive and tarnishes readily in the air and it can dissolve in the acid.
It oxidizes readily in the water ( slowly in cold water and rapidly in the hot water )
It can be burned heated or scratched with a knife
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Ionization Energies of Cerium
1st Ionization energy / kJ mol-1 is 534.41
2nd Ionization energy / kJ mol-1: 1046.87
3rd Ionization energy / kJ mol-1: 1948.82
4th Ionization energy / kJ mol-1: 3546.608
The world’s production of cerium is 23000 tonnes a year and is likely to increase in the future as the use of cerium is increasing day by day in our lives. The top 3 producers in the world are China, Russia, and Malaysia. Cerium is used commercially in industries as well as in household equipment.
It is used in low-energy light bulbs
It is used in cigarettes lighters
It is used in colour screen TVs
It is used in chromium plating
It is used in nuclear reactor
It is used in Lasers
It is used in microwave devices
It is used in aluminium and iron alloys
It is used in stainless steel as a hardening agent
It is used gas mantles, in gas lighting
It is used glass polishing agent
It is used to clean up exhaust vehicles through the catalyst of catalytic converters
It is used in making pigments for containers, toys, household wares and crates
It is used as the core of the carbon electrode in the arc lamp
It also catalysis the reduction of the nitrogen oxide to nitrogen gas
It is also used in the catalytic converter which consists of a ceramic or a metal substrate along with aluminium and is installed in every new car
Various health problems are caused by cerium. Nowadays more and more of the cerium is being used and using it in the working environment is almost dangerous because it is highly reactive in the air. The harmful damps and gasses can be inhaled with air through the respiratory system and if it accumulates in the human body, it can be a threat to the liver, lungs, especially during exposure for a long time and will also have a harmful effect if present for a short time also. It can also cause lung embolisms. It has also been noted that cerium stimulates salt metabolism and cerium also has no noted biological effect.
Cerium is environmentally undesirable. It accumulates in soil and water and thus can lead to intense concentrations in humans, animals, and in soil particles. Cerium is dumped by petrol-producing industries. It is thrown away by households also in various equipment when cerium enters the equipment. Cerium causes damage to cell membranes in water animals that can affect reproduction and nervous systems badly and have several negative influences on reproduction.
On a positive note, cerium is used as a catalyst. Cerium is used in catalytic converters to improve the atmosphere wherever diesel engines operate. Ceramic filters burn the particulates and carbon particles emitted by diesel engines. It catalyses the burning of the particulate and eliminates them.
Little cerium oxide can be added to the fuel itself so that it can catalyse the burning of the particulates and abolish them.
1. What are the sources for Cerium? How is it obtained for commercial use?
Cerium is available on the earth abundantly. It is found in minerals like allanite,bastnasite, monazite and samarskite.
Large deposits are available in Brazil, India and Southern California.
Using thermal reduction processes, it is extracted from the large deposits in its pure form.
But Cerium in its pure form, ignites readily when scratched using a sharp object.
To use commercially, it has to be combined with other materials safely.
Cerium is obtained by the ion exchange process from monazite sand.
Using an electromagnetic separation process, monazite sand is treated and separated from deposits.
After separation, on treatment with hot sulphuric acid, it gives water soluble Cerium. On further treatment with sodium hydroxide and ammonium oxalate gives insoluble Cerium oxides.