Centrifugation is a method for separating substances solid of liquid of different densities in a mixture , provided that the former is insoluble, employing the rotary force or centrifugal force.
For this purpose, an instrument called a centrifuge or centrifuge is often used, which rotates the mixture on a fixed and determined axis.
As its name suggests ( centrifugal : fleeing from the center ), this force tends to bring the denser components out of the axis of rotation, leaving the less dense at the center. It is contrary to the centripetal force.
Types of centrifugation
- Differential . Based on the density difference of the substances , it is the basic but inaccurate technique.
- Isopycnic . Different density media are used to separate particles with the same sedimentation coefficient.
- Zonal . The difference in the sedimentation rate of the substances (due to their different masses) is used to separate them in a certain centrifugation time.
- Ultracentrifugation . Its potency allows the separation of molecules and subcellular substances.
Examples of centrifugation
- The washing machine . This apparatus uses centrifugal force to separate (solid) clothes from (liquid) water based on their densities. That’s why the clothes are usually almost dry when removed from inside.
- Dairy industry . The milk is centrifuged to split its water and lipid content, since the latter are used to make the butter, or from the remaining skimmed milk.
- Cars in a curve . When we drive fast through a curve in the road, we often feel a force pulling us out of it, away from the axis of the curve. That is the centrifugal force.
- Obtaining enzymes . In the medical and pharmacological industry , centrifugation is often used to obtain certain enzymes from the specialized cells that produce them.
- DNA separation . Isopycnic centrifugation is often used in genetic laboratories to separate the cellular DNA and allow its further study and manipulation.
- Food for coeliacs . When separating the gluten protein from the foods that contain it, the centrifugation process becomes indispensable. It is carried out on starch paste, whose gluten content reaches 8%, and is reduced below 2% in successive selective centrifugations.
- Blood tests A centrifuge is used to separate the elements of the blood, such as plasma and other elements that are commonly mixed in it.
- Acceleration of sedimentation . In various food industries, such as brewing or cereals, centrifugation makes it possible to accelerate the sedimentation processes generated by gravity spontaneously, reducing the waiting time of the raw material .
- Latex cleaning . In the latex industry, it is necessary to clean the substance, whose surface is particularly prone to the adherence of other particles, and this is carried out through centrifugation, given the low density of the substance.
- Drying solid . Another industrial application of the centrifuge is the drying of crystals or other materials whose production is accompanied by water. When turning, the water separates from the solids and is discarded, leaving the desired solids without the liquid.
- Wastewater treatment . The centrifugation of contaminated water allows to extract dense substances inside, not only solid, but even oils, fats and other unwanted components that, once centrifuged, could be discarded.
- Amusement parks . Many attractions of amusement parks use centrifugal force to generate a vacuum effect on their users, who are rotated rapidly on a fixed axis, tightly fastened to a seat that prevents them from flying out of the axis of rotation.
- Pirouette motorcyclists . It is a classic of the circus motorcyclist in a sphere, which is able to drive through the roof of the same challenging gravity. This is able to do so after having made many turns on the same horizontal axis, accumulating speed and subjecting itself to the centrifugal force that adheres it to the interior of the sphere. Eventually this force will be so strong that it will be able to verticalize the movement and defy gravity.
- Tilt of train tracks . To counteract the centrifugal force, the train tracks are often tilted into curves, exerting resistance so that they do not succumb to the force that pushes them out and does not derail.
- The terrestrial translation . The reason that the gravitational force of the Sun does not push us head inward is also due to the centrifugal force that, by turning on the axis of the sun, pushes it outwards, counteracting and balancing the gravitational pull.