Simple Separation Methods

obtain pure material in the crystalline state.

s designed to minimize contamination of the crystals with other materials.

It a separation process that utilize semipermeable membranes to allow passage of certain chemical species completely, while stopping or strongly restrict the permeation of others.

Separate particles that differ significantly in size.

If the size of particles (or molecules):
>>pores sizes -> rejected to pass

<< pore size -> allowed to pass

intermediate pore size -> partially rejected

a homogeneous film or interphase through which a mixture of chemical species can be carried by molecular diffusion

Particles of exactly the same size can be separated with homogeneous diffusive-type membranes when their solubilities in the film or their concentrations differ significantly

The thinner the membrane; the faster the transport rates through membranes.

pore size as well as

exclusion of coions (ions of the same charge as
The fixed ions) from the membrane

Application of hydrostatic pressure between 1 & 10 atm to separate solutes with diameters > 20 Aْ

As a first preparation step for further separation.

As final step for obtaining an isolated material as a residue

Using an open container for a period of time

Application of heat

evaporation of seawater to get sea salt salt (NaCl)

t is the process of removing the solvent from a sample by heating or by utilizing air currents which lead to concentrate the sample or transfer it into a solid state.

Precipitation

By Increase the concentration of a solute in a solution to a higher level than its solubility

By carried out in (a proper solvent & a controlled manner)

Addition of another miscible solvent to the solution which lower the solubility of the component of interest

Addition of a species that form a lower solubility salt with the target species.

Common ion effect

Mainly organic & inorganic weak acids & bases

Porous material with a certain particle sizes (such as filter paper or membranes) allow the solvent to pass through while retaining the solids with particle sizes higher than the pore sizes.

separate solids from liquids.

Using Buchner funnel

Using Membrane Filters

Using simple filter papers (made from cellulose) and exhibit particle retention levels down to 2.5 μm.

Using gravitational force to separate solids from the liquid.

Distribution of solute between two immiscible solvents

Distribution of a solute concentration (C) between two solvents ( 1 and 2) during extraction can be represented by the following equation: Kc = C1/C2

Distribution Coefficient is used for one species.

Excluding all complications according the interactions between the extracted species and the used solvents; these interactions should be ignored to simplify the calculations. D = total concentration of solvent in organic phase/total concentration of solvent in aqueous phase

If Kc >1000 -> 1 signal extraction stage is enough to extract all of the target species.

If Kc < 1000 -> divide some of the extraction solvent into smaller portions and for each portion use successive extractions.

method of multiple liquid-liquid extractions is countercurrent extraction, which permits the separation of substances with different distribution coefficients (ratios)

evaporation but all the components of interest are volatile. while volatile components are separated from non-volatile ones in evaporation.

sublimation (highly specialized distillation method), is used to volatilize their component if possible .

for separation of the components of liquid mixtures.

It is based on the condensation of the hot vapor at verious levels in the column and the resulting liquid refluxes to a lower level where it is vaporized, which corresponds roughly to a re- distillation.

It is instantaneous and continuous vaporization of a definite fraction of the liquid mixture in such a way that the total vapor produced is in equilibrium with the residual liquid.

It is distillation under decreased pressure to reduces the boiling temperatures.

high-boiling mixtures.

materials that decompose below their normal boiling points.

The mixture boiling point tempreture is reduced by vaporixing it into a stream of carrier vapor

Any technique used to break an azeotrope (mixtures that are difficult to separate) in distillation.

Adding another component to alter the relative volatility of the mixture substances and form lower-boiling azeotrope that is heterogeneous.

To separate mixtures whose components boil too close together for economic fractional distillation.

Formation of two immiscible liquid phases by addition of benzene to water and ethanol.

separated on a packed or capillary column

HPLC