Buchner Funnel Vacuum Filtration

Buchner funnel vacuum filtration

Buchner funnel vacuum filtration system is a technique whereby suction is applied to a mixture of liquid and solid. It is always ideal whenever there is a need to separate and keep the precipitate safe from a solution by applying the suction technique.


Buchner funnel vacuum filtration setup requires the following apparatus: filter flask, filter trap, water pump, a gadget that makes the system efficient into the aspirators-which works on the principle of blocking access into the vacuum when water is passing over as is seen in the water tap system.

Other equipment used in assembling the Buchner funnel vacuum filtration apparatus is; the non-reusable filter funnel and a filtrate receptacle.


Assembling The Apparatus

Fit the non-reusable filter funnel into the filtrate receptacle. After mounting the funnel and the filtrate on the base, a vacuum is applied by using a connection passage linking to the receptacle.


The side-arm of the Erlenmeyer flask is clamped to a ring stand and a thick rubber hose is attached to it. The tubing is now connected to a vacuum trap as well as to the aspirator.

Place a rubber sleeve and Buchner funnel on top the sidearm Erlenmeyer flask. Place a filter paper that fits squarely into the Buchner funnel.


Procedure Of Filtration

Contaminated water is poured into the filter. Using a water pump, the liquid part is sucked into the flask. The water aspirator is used to develop suction through the Bernoulli Principles.

The filtrate is kept inside the flask but any liquid that overflows the flask is taken care of by the filter trap. The precipitate left behind is now held on the surface of the filter. The precipitate is then rinsed to get a finer and purer solid.


Advantages Of Using Buchner Funnel Vacuum Filtration

i. It makes use of readily available Spunbond which comes in varying and effective pore sizes

ii. It uses a suction technique making it faster than gravity filtration.

iii. It is more efficient at removing residual liquid to give out a purer solid than gravity filtration.


Disadvantages Of Using Buchner Funnel

a. The filter paper pores can permit finer solid particles to penetrate during suction.

b. Not recommended for microscale purposes as it may result in a significant loss of the targeted filtrate.

c. Can only be conducted with a funnel that has flat surfaces like the Hirsch or Buchner funnel.

d. Not suitable for the solvent with low boiling points. Such solvent would just evaporate, while the dissolved solids upon precipitating, would clog up the filter pores and get stuck on the inside of the funnels.

e. Lastly, this method is not recommended for hot solutions since the solvents in such a case are close to their boiling point.

stainless steel buchner funnel



Given the speed at which the filtration process is done when the Buchner funnel vacuum filtration technique is applied, I would recommend it for well-stocked laboratories and for scientists who want more accurate results.

Finally, a word of caution: special attention should be paid as working with reduced pressure requires that the glassware used is free of any form of cracks.

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