A Buchner funnel is a piece of chemistry labware used to make filtrations. It is traditionally produced in porcelain, so it is classified among the porcelain material. But they are also available in glass and plastic, because of their low cost and less fragility, used mainly in secondary schools.
DESIGN
Its design has been erroneously attributed to the Nobel Prize in Chemistry, Eduard Buchner, but its design is currently attributed to the industrial chemist, Ernst Büchner.
STRUCTURE AND USES
Above the funnel-shaped part is a cylinder separated by a perforated porcelain plate with small holes. The filter material (usually filter paper) is cut into a circular shape and placed on the plate. The liquid to be filtered is dumped into the cylinder, and sucked through the screened plate by a vacuum pump created with the Venturi effect, by means of a kitasate and a stream of water.
Before placing the filter paper, it must be cut so that it covers the holes in the porcelain but without raising it on the side walls. To do this, the paper is moistened with distilled water to fix it to the base. The funnel is provided with a frustoconical rubber ring or joint that fits perfectly in the mouth of an Erlenmeyer flask with a lateral nozzle, called a kitasato.
This type of [embudos (laboratorio)|embudo]]is used in the filtration of suspensions containing large solid particles. If it is done with small solids, when vacuuming and being sucked, it can pass to kitasate. When the filtrate is important and must be collected, it is advisable to place a trap between the Erlenmeyer flask that receives the filtrate and the water nozzle or suction nozzle, because there is a danger that the water will return and contaminate the filtrate.
