Büchner funnel, what is it and how to choose it?

November 2, 2021

Büchner funnel is a laboratory tool used for filtration functions. The material with which it is usually made of porcelain, but there are also glass and plastic versions.

The Hirsch funnel has a similar design; it is used in a similar way, but for smaller amounts of material. What differentiates one funnel from the other is that while the Hirsgch funnel is smaller compared to what is being discussed in this article. Also, its walls lean outward rather than remain vertical.

Filtration is a simple, slow , gravity process that requires a piece of filter paper. There are quick ways to filter, this is with a funnel. The bücnner funnel is a device used for pressure-assisted filtration.

The funnels are intended for the functions of the chemical laboratory, so it is normal that they come in different types. Which are adapted to the work of specific applications. Some of these types of funnels include filter, thistle, flower-shaped, and drip. The latter have taps that allow the liquids to be added slowly to a flask.

Next, we will talk in detail about one of the laboratory elements, which together with the beaker , cannot be missing from the table. Join us!

What is a Büchner funnel?

A Büchner funnel is a device whose basic function is to remove the unwanted solid from the liquid . Generally speaking it is a piece of filter paper in the funnel, which acts as a filter agent. It blocks the mixture of the liquid and the solid is passed through the filter, which also has the solid particles and the remains are passed to the collecting flask.

S and can use a funnel with a sintered glass disc immediately. For a funnel with a perforated plate, the filter material in the form of filter paper is placed on the plate, and the filter paper is moistened with a liquid to prevent initial leakage. The liquid to be filtered is poured into the cylinder and sucked through the perforated plate or fritted glass disk by vacuum suction.

When the funnel is used with a filter paper, which is known as a filter funnel, the buchner funnels can be used to remove fine particles from a specific liquid during a process called filtration. For more demanding applications, the filter paper can be replaced with a synthesized glass frit.

History of the büchner funnel

Filtration has long been a tedious process, and in the 1880s the search accelerated, especially for large-scale reactions. Increasing the pressure difference across the filter medium could be achieved in two ways. One was the filter press, by which the mother liquor was literally squeezed out by means of a horizontal or vertical piston, a method suitable for large-scale operations. The alternative was to use a vacuum to draw in the solvent.

Less than six months after Hirsch’s report , the manager of a medium-sized grocery factory in the town of Pfungstadt, outside Darmstadt in Germany, Ernst Wilhelm Büchner, published his design, a modification of Hirsch but with vertical sides. , which allowed him to handle a much larger volume of solution.

The most respectable Wilhelm studied chemistry, first with Gmelin and then with Liebig. Returning to Pfungstadt in 1841, he began playing games in his home laboratory and discovered a way to make ultramarine, the synthetic analog of the precious mineral lapis lazuli. The business took off and Büchner used the proceeds to buy property, then moved into national politics, championing the liberal causes championed by his older brother.

Büchner funnel design

A Büchner funnel is an object in which, worth the redundancy, it has the shape of a funnel, and the material from which it is made is enameled porcelain. Although it is also normal that glass and plastic funnels are available . Classic Büchner funnels have a long, thin glass tube to drain the filtered liquid, although some models have a ground glass gasket or a side vacuum inlet tube, or both.

Büchner funnels are often used with a side-arm flask. Also known as a Büchner or Kitasato flask when vacuum filtration is done. Although if vacuum adapters are used, ordinary flasks can also be used. Jacketed Büchner funnels are a special type sometimes found in laboratories, they are often used when doing cold or hot filtering.

Glass is the material of choice for laboratory applications due to its inertia compared to metals or plastics. However, plastic funnels made of non-reactive polyethylene are used to transfer aqueous solutions. Plastic is most often used for powder funnels that do not come into contact with solvents in normal use.

Uses of the büchner funnel

Vital in the field of organic chemistry, this funnel is primarily used to collect recrystallized compounds throughout the process. Vacuum suction dries the wet crystal compounds so that the dry compounds stay out. In addition, its use is often combined with sintering seals, a Büchner ring and a flask. All of these components are quite essential during the filtration process.

The other uses are:

  • On brand glass bottle
  • In tabletop liquefied gases: cryogenic vacuum flask
  • In the phase separation of plants and their components: filtration plants.
  • In filter cloths: industrial filters
  • Inexpensive, cool, durable, and rugged pumps: Portable Vacuum Pumps
  • In gas distillation and extraction units: Sigma process plants
  • In vacuum systems with steam jet ejector: steam jet ejectors

This is perhaps one of the most essential and widely used equipment that you would find in any chemistry lab. It helps speed up a chemical process and makes your job much easier.

Types of büchner funnel

  • The simple funnels exist in several dimensions, with necks longer or shorter.
  • The filter funnel usually has a thin capillary tube which is called a neck, and ribs that increase the effectiveness of the work for filter papers.
  • The powder funnels have a narrower and wider neck for quick pouring of powders.
  • The separating funnels have a distinctive pear shape, have a lid and a reduced neck compared to the rest, with a stopcock for uniform pouring of fluids.

Advantages of the büchner funnel

The main advantage of using these funnels in laboratories is that the filtration process, which is extremely important in experiments, will quickly filter the liquid thanks to the force of gravity. If the amount of liquid you intend to use is limited, it will overflow the flask. If not, the liquid will be drawn into the vacuum.

If the water flow device provides the vacuum, an overflow of the liquid could cause a dangerous liquid to spill into the wastewater stream, a possible violation of the law, depending on the liquid. The potential for overflow and the potential for water to return to the flask can be reduced by using a trap between the flask and the vacuum source.

Büchner funnel maintenance

The funnels Büchner porcelain not be used to filter extremely corrosive reagents, and that can slowly corrode the protective enamel. Büchner funnels with fried discs are known to be difficult to clean. If a base bath is used, they should not be left for more than one day as the base will dissolve the glass bond between the sintered glass particles.

A strong oxidizing solution, such as aqua regia or, in extreme cases, a piranha solution can be used to remove even the most stubborn stains. These mixtures are among the few chemicals that can destroy graphite.

Availability of the büchner funnel

Büchner funnels can be purchased from laboratory suppliers, both in porcelain disc and sintered glass models. Büchner plastic funnels are also available. Büchner funnels made of aluminum or stainless steel can be found in many hardware stores, as spare parts for coffee makers. Hirsch funnels can also be purchased from laboratory vendors and online. Hirsch plastic funnels can sometimes be found in hardware stores, albeit of lower quality.

Hirsch’s Embu

Similar in construction to the Büchner funnel, the Hirsch funnel has an almost identical appearance to a classic funnel, with the funnel walls angled outward rather than vertical. The funnel has a small diameter perforated disc near its “neck.” They are sometimes used to filter small amounts of material or dilute suspensions.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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