The Buchner funnel pump is a precision filtration apparatus commonly used in organic chemistry. The device separates fine solids from a solution of solids and certain solvents. Recrystallized compounds in a solution are preferably collected through this device.
The Design Of Buchner Funnel Pump
Buchner funnel has three main parts. These include the funnel at the top, as well as the flask, and the pump. Integral to the funnel is a cylindrical section that holds the solution to the filter. At the intersection of the cylindrical section and the funnel is a perforated section. This section has an inbuilt plate with small holes that pass the liquid into the flask.
On top of the perforated plate is a design that allows you to place the filtering paper. Through a sealed connection, the funnel is attached to the flask at the bottom. The vacuum pump is connected to the flask through sealed tubing.
Working Of Buchner Funnel Pump
To begin with, you first moisten the filtering paper and then place it on the perforated section. The moistening is necessary so as to prevent any leaks through the paper. You then pour the solution to filter in the Buchner funnel pump, after which you run the pump.
This creates a vacuum suction that makes it possible to draw the liquid rapidly through filtering, after which the liquid is taken into the flask and the filtered solid is left on top of the filtering paper. For high-precision solid collection, you have to oven-dry the collected solid from the Buchner funnel pump so as to remove the residual liquid.
Advantages Of This Particular Funnel Pump
• Since the funnel is comparatively bigger than other filtering devices, you are able to filter a bigger volume of solution at one go through this funnel pump.
• The filtering elements are very fine. Therefore, the solids you are able to collect through this filtering process are also much finer than those collected through other filtration processes.
• Buchner funnel pump uses suction to pull the liquid through the filtering element. This is a different process from the gravity-fed filtration of other filtering devices. The suction speeds up the process and a bigger volume of solution can be filtered in a short span of time.
• Since the filtering paper is replaceable, a repeat filtration can be done within a short interval of completing one.
• It prepares the collected solid for further drying if required.
Precautions To Operate The Buchner Funnel Pump
Spillage through the rims of the funnel can dilute and often spoil the whole process. Care should be taken to control spillage and mixing of fluids at any stage of the filtration. The connecting points all along the device should be sealed and sufficiently secured.
The filter paper is often fluted, to further speed up filtration. The creases around the fluting can often allow unfiltered fluid to seep through. This will result in a loss in fluid volume and less collected solid.
The funnel pump filtration is more suitable for collecting finer solids without much trace of water in them. For collecting much bigger particles of solid, there are easier and cheaper methods of filtration.
Liquids can also be collected through this process. However, it is very tough to maintain the purity of the liquid collected. There are many places where the liquid comes in contact with the impure solution and gets spoilt. If the process is used for liquids, you should exercise the utmost care.