Wheel of Separation Processes

A separation process is a scientific method or technique that converts a mixture or a solution of chemical substances into two or more distinct product mixtures to obtain purity.

Centrifugation is a mechanical process which uses the centrifugal force to separate particles from a solution as per their size, shape, density, medium viscosity and rotor speed. The denser components of the mixture migrate away from the centrifugal axis, while the less dense components drift toward the axis. The clear liquid remaining above the centrifuged solid phase (called precipitate) is known as the supernate or supernatant.

In chromatography the mixture of analytes (often called a sample) to be separated into its components, based on the differences of their polarities (Mnemonic: like likes like), is dissolved in a fluid solvent (gas or liquid) called the mobile phase, which carries it through a system (a column, a capillary tube, a plate, or a sheet) on which a material known as the stationary phase is fixed.

In decantation the less dense of the two immiscible liquids (top layer), or the liquid from which the precipitate or sediment has settled out is (incompletely) poured off, leaving denser liquid or the solid behind.

Evaporation is a type of vaporization which happens on the surface of a liquid to be separated from a solid as the liquid gradually changes into the gas phase on gently heating the mixture to dryness; and therefore, is temperature dependent.

Liquid–liquid extraction (LLE) is a method to separate solutes (called analytes) based on their relative solubilities in two different immiscible liquid phases (referred to as distribution/ partition), often water and an appropriate organic solvent (frequently known as extracting solvent). Solid-phase extraction (SPE), on the other hand, is a solid-liquid extractive technique, by which analytes dissolved or suspended in a liquid mixture are isolated (purified) from other compounds in this mixture (so-called matrix), as per their physical and chemical properties.

Filtration physically separates a solid from fluid in a mixture using a filter medium that allows only the fluid to pass through (known as filtrate).

Flotation is a process of separating minerals by agitating a mixture with water and detergents, etc., selected substances being carried to the surface in air bubbles. Precipitation is the sedimentation of a solid from a liquid in an aqueous solution. Coagulation and flocculation involve the addition of compounds that promote the clumping of fine floc into larger floc s.t. they can be more easily separated from the water. The former is a chemical process which needs neutralization of charge whereas the latter is a physical process which does not encompass charge neutralization. Salting out (aka salt-induced precipitation, salt fractionation, anti-solvent crystallization, precipitation crystallization, or drowning out) is a purification technique that leverages the reduced solubility of certain molecules (typically large biomolecules, viz., proteins or DNA) in a solution of very high ionic strength.

Fractional distillation is the separation of a mixture of chemical compounds into its components (aka fractions), which generally have boiling points that differ by < 25°C (45°F or 298 K) from each other under a pressure of 1 atm, by heating them to a temperature at which one or more fractions of the mixture will vaporize (aka distill).

Magnetic separation is the process of separating components of mixtures by using a magnet to attract magnetic substances.

Recrystallization is a broad class of chemical purification techniques characterized by the dissolution of an impure sample in a solvent or solvent mixture, followed by some alteration in conditions which drives the formation of pure isolate as solid crystals.

Sieving (aka sifting or screening) is a technique used for separating wanted elements from unwanted materials or for controlling the particle size distribution of a sample, using a filter, viz., a woven fine mesh strainer or net or perforated sheet material.

Distillation (aka classical distillation) is the separation of the components of a mixture of chemical compounds by selective boiling of the mixture and the condensation of the vapor in a still. In simple distillation, the vapor is immediately channeled into a condenser; and therefore, the distillate may not be pure, but rather its composition is identical to the composition of the vapor at the given temperature and pressure, which follows Raoult's law. Simple distillation is carried out only when the liquid boiling points differ by ≥ 25°C (45°F or 298 K).

Wheel of separation processes: Click/tap to enlarge the image

s = Solid, l = Liquid, DNA = Deoxyribonucleic acid

What other wheel(s) 🛞 of organic reactions would you like to see❓Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

(1)    Centrifugation. Wikipedia. https://en.wikipedia.org/wiki/Centrifugation.

(2)    Wikipedia Contributors. Chromatography. Wikipedia. https://en.wikipedia.org/wiki/Chromatography.

(3)    Wikipedia Contributors. Decantation. Wikipedia. https://en.wikipedia.org/wiki/Decantation.

(4)    Wikipedia Contributors. Evaporation. Wikipedia. https://en.wikipedia.org/wiki/Evaporation.
(5)    Wikipedia Contributors. Extraction (chemistry). Wikipedia. https://en.wikipedia.org/wiki/Extraction_(chemistry).
(6)    Wikipedia Contributors. Filtration. Wikipedia. https://en.wikipedia.org/wiki/Filtration.
(7)    Wikipedia Contributors. Froth flotation. Wikipedia. https://en.wikipedia.org/wiki/Froth_flotation.
(8)    Wikipedia Contributors. Precipitation (chemistry). Wikipedia. https://en.wikipedia.org/wiki/Precipitation_(chemistry).
(9)    Wikipedia Contributors. Coagulation (water treatment). Wikipedia. https://en.wikipedia.org/wiki/Coagulation_(water_treatment).
(10)    Wikipedia Contributors. Salting out. Wikipedia. https://en.wikipedia.org/wiki/Salting_out.
(11)    Wikipedia Contributors. Fractional distillation. Wikipedia. https://en.wikipedia.org/wiki/Fractional_distillation.
(12)    Wikipedia Contributors. Magnetic separation. Wikipedia. https://en.wikipedia.org/wiki/Magnetic_separation.

(13)    Wikipedia Contributors. Recrystallization (chemistry). Wikipedia. https://en.wikipedia.org/wiki/Recrystallization_(chemistry).

(14)    Sieve. Wikipedia. https://en.wikipedia.org/wiki/Sieve.

‌(15)    Distillation. Wikipedia. https://en.wikipedia.org/wiki/Distillation#Simple_distillation.

(16)    Wikipedia Contributors. Separation process. Wikipedia. https://en.wikipedia.org/wiki/Separation_process.