The Electrostatic Precipitator

Repelling Pollution

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Above is a diagram of an industrial electrostatic precipitator.

What does it do?

The electrostatic precipitator is a clever and useful way to remove harmful particles and liquid droplets from the gas leaving the smokestacks of factories. Harmful by-products are produced during the process of burning coal and smelting ore. These by-products include sulphuric acid, smoke and ash. Inhaling these toxins can cause many health concerns, such as cancer(“Air Purifiers”). Another harmful chemical removed by electrostatic precipitation is sulphuric dioxide. This substance, when mixed with water vapour in the Earth’s atmosphere causes acid precipitation. Acid precipitation has the ability to ruin many ecosystems by changing the acidity levels of water bodies. This change may lead to the loss of species, which will disrupt the food web causing harm to many organisms (Woodford). By placing precipitators on smokestacks air will be cleaner everywhere. This shows that the application of electrostatics can save the environment, and countless lives.


The electrostatic precipitator was first patented in 1907 by Frederick Cottrell (Blake et al.). However, in 1824 M. Hohlfeld, a mathematics teacher in Leipzig, Germany, was the first to describe the precipitation of smoke particles by electricity. Precipitation is the process by which a solid is separated out of a solution. This is similar to when a solid or precipitate forms in a liquid during a chemical reaction. Cottrell began his work on the precipitator in 1906 in California. Four years later he succeeded in creating the first precipitator ready for industrial use. His idea quickly became a huge success. The electrostatic precipitator was first used by smelting and cement plants, but today it is used mainly by coal power plants and metal mills. Contrell eventually sold his patent and used the money to fund other research in fields such as space travel (“Frederick Gardner Cottrell”).

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Above is a picture of Frederick Cottrell.

How does it work?

An electrostatic precipitator uses the law of electrostatic charges to catch pollutant particles and liquid droplets in polluted gas. As these particles and droplets move through the bottom of the smokestack they come into contact with negatively charged electrodes (Woodford). An electrode is a conducter through which electricity enters or leaves. The particles will always come into contact with the negative electrodes, as the law of electrostatic charges states that charged objects attract neutral objects (Blake et al).

Once the particles are in contact with the electrodes, electrons move to the particles from the electrodes as they are repelled by the electrodes' negative charge. However, there are not enough electrons leaving the electrodes to make the electrodes neutral, so they remain negative. In other words there still are more electrons than protons in the electrodes. The particles have now gained electrons, making them negative as well. This follows the law of charging by contact, as when the charged electrode came into contact with a neutral pollutant particle, both took on the negative charge of the electrode. Since both the particles and the plates are now negatively charged they repel each other, and the pollutant particles continue on their way.

Now all the pollutant particles are negatively charged. They are collected in two different ways, one with neutral collection plates, and another with positively charged collection plates.

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This is a model of an electrostatic precipitator with positively charged collection plates.
The first method is to use positively charged collection plates. Since the plates are positively charged and the pollutant particles are negatively charged, they will be attracted to each other (“Electrostatic Precipitators”). We know this because the law of electrostatic charges states that unlike charges attract. The pollutant particles are scraped or are shaken off the electrodes. (Encyclopedia Britannica). Cleaner gas then flows out of the smokestack.
The second method uses neutral collection plates. When the collection plates are neutral induced charged separation will play a large role in the collection of the particles. The collection plates are grounded so when the negative pollutant particles come close to a neutral plate, the electrons in the plate move to the ground. This is because the electrons are repelled by the pollutant particles’ negative charge. The collection plate is now positive, allowing it to attract the negatively charged particles. In other words the pollutant particles charged the plate by induction. When the negative pollutant particles come into contact with the plate, electrons flow from the pollutant particles through the plate, to the ground until the pollutant particles are neutral. At this point, the neutral particles will not be attracted to the neutral plates, so they fall into collection hoppers. The result, again, is cleaner gas being released by the smokestack (Blake et Al.).
Electrostatic Precipitator System Working.avi
This is a model of an electrostatic precipitator. The pollutant particles are given a negative charge, so they attract and stick to the collection plates. Other particles, however, pass through the machine and the result is cleaner gas let out of the smokestack (Blake et al).

Learn More About Electrostatic Precipitators

Works Cited

"Air Purifiers Filtering the Claims." Consumer Reports. N.p., 1 Dec. 2007. Web. 10 Feb. 2013. <>.

Electrostatic Precipitation. 2008. Electrostatic Precipitation. Web. 5 Feb. 2013. <>.

"Electrostatic Precipitation." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition. Encyclopædia Britannica, Inc., 2013. Web. 7 Feb. 2013.


Electrostatic Precipitator . 2013. Neundorfer. Electrostatic Precipitator KnowledgeBase. Web. 11 Feb. 2013. <>.

Electrostatic Precipitator System Working.avi. 1 Mar. 2012. Youtube. Web. 11 Feb. 2013. <>.

"Electrostatic Precipitators." N.p., 2013. Web. 10 Feb. 2013. <>.

"Frederick Gardner Cottrell." World of Invention. Gale, 2006. Gale Science In Context. Web. 14 Feb. 2013. <>

History. 2013. Runaway history list. Web. 6 Feb. 2013. <>.

How does it work. 2013. How does a Vacuum Work. Web. 6 Feb. 2013. <>

Kurtus, Ron. How a smokestack electrostatic precipitator works. 2009. School for Champions. Web. 11 Feb. 2013. <>.

Maczulak, Anne. Environmental Engineering. 2009. Infobase Ebooks. Web. 10 Feb. 2013. <>.

ON Science 9. Whitby, ON: McGraw-Hill Ryerson, 2009. Print.

Plate Precipitator. 2013. Electrostatic Precipitator. Web. 11 Feb. 2013. <>.

Woodford, Chris. "Electrostatic Smoke Precipitators." Explain That Stuff!. N.p., 7 July 2012. Web. 10 Feb. 2013. <>.