Solid-liquid purification

Filtration is a solid-liquid purification technique used to separate solids from a liquid, in a suspension. They separate compounds based on one property, their (in)solubility in a solvent.

There are two main kinds of filtration, gravity and vacuum filtration. Gravity filtration is the kind you use to filter your morning coffee, by pouring your coffee through the filter paper and waiting for your drink to drip and collect. Vacuum filtration is identical except the collecting flask is connected to a vacuum and your liquid is drawn far faster through the filter paper and into the flask. Vacuum filtration is generally used to speed up filtration when it is repeatedly used.

Figure 1: Image showing how to vacuum filter a suspension