When we follow the preparation of coffee, we easily see that the person performs a procedure to remove excess dust from the water using a filter paper in a funnel or a strainer. cloth. This procedure, which is a common filtration, is widely used in several areas and branches of human activities, and not only in the preparation of coffee.
THE common filtration it's the separation method used to separate the components present in mixtures classified as heterogeneous. The objective is the complete separation of the solid contained in the mixture. The types of heterogeneous mixtures separated by this method are:
Solid in a liquid (Example: water and sand);
Solid in a gas (Example: dust and air).
When performed in a Chemistry laboratory, the materials and equipment used are:
a) Beaker
Representation of a beaker
b) Universal Support
Representation of a universal support
c) Simple glass funnel
Representation of a glass funnel used in filtration
d) Filter paper
Filter paper used in filtration
e) Gripper or ring
Representation of a metal claw for universal support
The function of each of these materials is best understood when we explain the steps in separating a mixture by filtration. We will use as an example the mixture of water and sand. Follow:
1O) We adapt the claw or ring to the universal support;
Universal support with adapted claw
2O) Next, we attach the glass funnel to the claw or ring;
Funnel adapted to the claw
3O) We place the beaker on the underside of the glass funnel;
Beaker positioned under the funnel
4O) We put the filter paper inside the glass funnel;
5O) We start to pour the mixture formed by water and sand inside the funnel with the filter paper;
6O) The filter paper starts to retain the sand and allows only the water to pass through, which falls into the beaker and is collected.
Ordinary filtration can also be performed using a glass funnel with filter paper inside an Erlenmeyer flask, as shown in the image below:
Ordinary filtration performed simply
With this explanation, it is clear that, during coffee preparation, the objective of using the role of filter or cloth strainer is the same as any common filtration, that is, retaining excess material solid. This same explanation can be given for several other situations, such as:
Using a vacuum cleaner: the equipment sucks (sucks) air and solid impurities into its interior. There is a cloth container there that prevents the passage of solid content and allows the passage of gas;
Place a piece of activated carbon inside the refrigerator: When the air that circulates through the refrigerator passes through the charcoal, it retains in its interior all the molecules of substances that cause odor inside the refrigerator;
Washing clothes: When we are washing clothes, the soap interacts with the impurities, forming large solid flakes. When water passes through clothing, it drags these flakes; thus, clothing works as a filter;
After oil extraction at sea: whenever oil is extracted in maritime regions, it is accompanied by sand. Therefore, the filtration method is carried out to remove all the sand present in it;
In food and beverage industries, to remove unwanted solid materials present in the mixture.
By Me. Diogo Lopes Dias
