Difference Between Separation and Extraction
Key Difference: Extraction is a method used for the separation of organic compound from a mixture of compound. This technique selectively dissolves one or more compounds into an appropriate solvent. Whereas separation process is a method that converts a mixture or solution of chemical substances into two or more distinct product mixtures. At least one of results of the separation is enriched in one or more of the source mixture's constituents.
Defined by Britannica.com,” Separation is a process that changes the relative amounts of substances in a mixture. In chemical methods, one may start with a completely homogeneous mixture (a solution) or a heterogeneous sample (e.g., solid plus liquid); in the act of separation, some particles are either partially or totally removed from the sample.”
In our surrounding most of the materials are mixtures of two or more components. Mixtures are either homogeneous or heterogeneous. Where homogeneous mixtures are uniform in composition, heterogeneous mixtures lack uniformity in their composition.
Air is a homogeneous mixture and oil in water is a heterogeneous mixture.
Separating the constituents of the mixtures, makes it easier to find out and understand the properties of the known/unknown substances from mixtures. And this advantage allows one to possibly use them for the production of useful substances such as medicines.
Depending on the physical and chemical properties of the substances in the mixture, the most appropriate separation technique is chosen to isolate them from the mixture.
Reasons for making separation
According to Britannica.com,” There are two general reasons for performing separations on mixtures. First, the mixture may contain some substance that should be isolated from the rest of the mixture: this process of isolating and thus removing substances considered to be contaminants is called purification. For example, in the manufacture of synthetic drugs, mixtures containing variable proportions of several compounds usually arise. The removal of the desired drug from the rest of the mixture is important if the product is to have uniform potency and is to be free of other components that may be dangerous to the body.
The second reason for performing separations is to alter the composition of a sample so that one or more of the components can be analysed. For example, the analysis of air pollutants to assess the quality of the air is of great interest, yet many of the pollutants are at a concentration too low for direct analysis, even with the most sensitive devices. Pollutants can be collected by passing samples of air through a tube containing an adsorbent material. By this process the pollutants are concentrated to a level such that straightforward analysis and monitoring can take place. In a second example, several impurities in a sample may interfere with the analysis of the substance of primary interest. Thus, in the analysis of trace concentrations of metals in rivers, organic substances can cause erroneous results. These interferences must be removed prior to the analysis.”
The choice of separation techniques is based on the type of mixture and difference in the chemical properties of the constituents of a mixture.
Various types of separation processes are:
- Simple distillation
- Fractional distillation
- Separating funnel
- Magnetic separation
Extraction is a process used to remove a desired compound from a solid or a liquid mixture using a suitable solvent. It is never possible to completely extract or remove a compound from a given solvent; ideally very little impurity will be left behind. There are three types of extraction; solid/liquid, liquid/liquid, and acid/base extraction. Solid liquid involves the removal of a substance from a natural product or solid mixture (i.e. hot water and tea/coffee). Liquid/liquid extraction involves the transfer of the desired compound from one liquid to another. Often times, a substance is soluble in water, but much more soluble in a different solvent (usually organic) so the compound becomes dissolved in the second organic solvent. Last is acid/base extraction in which an acid (H3O+) or base (OH-) is added to a mixture causing an unwanted impurity to react and become a solid. This solid is easily filtered out. (Ben Dunmire)
Professor Lisa Nichols explains, “Extraction refers to transference of compound(s) from a solid or liquid into a different solvent or phase. When a tea bag is added to hot water, the compounds responsible for the flavour and colour of tea are extracted from the grounds into the water. Decaffeinated coffee is made by using solvents or supercritical carbon dioxide to extract the caffeine out of coffee beans. Bakers use the extract of vanilla, almond, orange, lemon, and peppermint in their dishes, essences that have been extracted from plant materials using alcohol.”
There are several reasons to use extraction in the chemistry lab. It is a principal method for isolating compounds from plant materials. Extraction moves compounds from one liquid to another, so that they can be more easily manipulated or concentrated. It also enables the selective removal of components in a mixture.
Uses of Extraction Method
1.Extracting Natural Compounds
2. Transferring Compounds from Layers
3. Selective Removal of Components
References:britannica.com,chemistrynotesblog.wordpress.com,amrita.olabs.edu.in, lehighcheme.wordpress.com, chem.libretexts.org(Overview of Extraction and Uses of Extraction), vlab.amrita.edu,wikipedia.org Image Courtesy:tes.com,blog.edenlabs.com