Separation Techniques

 

Separation Techniques

Basis for separation- different component different properties

Strategy: devise a process that discriminates between components with different properties

Separation

Components in a mixture retain their identities

The more similar the properties are, the more difficult it is to separate them

Basis Techniques

Filtration

Floatation

Crystallization and Extraction

Distillation

Chromatography

Hand separation and Evaporation- Boil away the liquid and the solid remains (solid to solid)

A mechanical mixture of heterogeneous mixture can be separate by using a magnet

Filtration (solids (not dissolved) and liquids)

-Pass a mixture through a porous filter

Crystallization (solid in liquid)

-Precipitation, solids are then separated by filtration or floatation

Saturated solution of a desired solid

Evaporate or cool- solid comes out as pure crystal

Gravity (solids based on density)

-A centrifuge whirls the test tube around at high speeds forcing the denser materials to the bottom. Work best for small volume.

Solvent Extraction

-Mechanical mixture- use liquid to dissolve one solid but not the other so the desired solid is left behind or dissolved

Solution- solvent is insoluble with solvent already present

Distillation (liquid in liquid solution)

-Heating a mixture can cause low boiling components to volatilize (vaporize)

Chromatography

-Flow the mixture over a material that retains some components more than others, so different components flow over the materiel at different speeds

-Sheet

        Paper Chromatography (PC)

-stationary phase is liquid soaked into a sheet or strip of paper

-components appear as separate spots spread out on the paper after drying or “developing”

        Thin layer chromatography (TLC)

Stationary phase is a thin layer of absorbent (Al2O3 or SIO2, usually coating a sheet of plastic or glass)