Adsorption chromatography uses the difference in adsorption capacity of substances in stationary phase adsorption to achieve separation of the mixture. The chromatographic process of adsorption chromatography is the process in which the mobile phase molecules compete with the material molecules for the stationary phase adsorption center.
Physical adsorption, also known as surface adsorption, is caused by the interaction between the molecules (containing solutes and solvents) constituting the solution and the molecules of the surface molecules of the adsorbent.
a) Basic law: “similars are easy to adsorb”.
b) Basic characteristics: no selectivity, reversible adsorption, fast.
c) Basic principle: reciprocating cycle of adsorption and desorption.
d) Three elements: adsorbent, solute (isolate), solvent.
e) Physical adsorption process: adsorption – desorption – resorption – reanalysis – until separation
a) Basic characteristics: selective and irreversible adsorption.
b) Basic principle: Produce a chemical reaction. The acidic substance reacts with Al2O3; the basic substance reacts with silica gel; Al2O3 is prone to structural isomerization and should be avoided as much as possible.
a) Basic characteristics: between physical adsorption and chemical adsorption.
b) Basic principle: adsorption occurs in the form of hydrogen bonds.
For example, hydrogen bonding between polyamides and other compounds such as flavonoids and terpenoids.