How to Select the Vacuum Filtration or Gravity Filtration？
There are two types of filtration that are widely used in organic chemistry labs, one is called gravity filtration which is the traditional form of filtration forced by gravity. It’s easy to set, but might come out with poor results in low speed sometimes, and the other one is vacuum filtration. It pushes material through the filter in the Buchner funnel by using a pump that can generate. Both of them can remove solid impurities from an organic solution or isolate an organic solid.
Selecting the right filtration method depends on the nature of the experimental situation. Here are some tips you should think about.
As the method of removing solid impurities such as a drying agent, an undesired side product, or a kind of reactant leftover, gravity filtration can be used to collect the solid from an organic liquid. Actually, you can find that vacuum filtration can do that too, but much fast then gravity filtration.
Although the vacuum filtration is faster than the gravity one, there is something important you should know when you take the vacuum filter into use. First, the glass filter flask must not have any cracks on the bottom of the sides. Second, you have to make sure that the filter flask and the vacuum trap are clamped tightly, and they will not move during the filtration.
It’s important that the clean filter flask, the vacuum trap, and the tubing are made of thick-walled glassware. The water hoses might collapse during the vacuum process if you use the normal tubing.
Remember, don’t perform a vacuum filtration without a vacuum trap and always keep the trap clean. If there is something sucked in there, you will find that easier to recover it from a clean trap then from a dirty one.
If you want to collect the solid, vacuum filtration might be the best according to its high speed. If what you want to collect is the filtrate, gravity filtration methods are highly recommended.
The gravity filtration will the better choice when you have a large volume to filter. Vacuum filtration is good on the one hand because it’s pretty fast, but on the other hand, the risk of spills will increase and the speed will slow down when you need to empty the flask partway through releasing the pressure and removing the funnel. The vacuum filtration is also preferred if there is only a small amount of solids to be collected or if solid is fine.