1, C-C bond in activated carbon is nonpolar, and activated carbon molecules can be regarded as nonpolar;

Although there are polar bonds such as carboxyl and hydroxyl on the surface of activated carbon, they are much less than C-C bonds.

2. Water is a polar molecule, and most gases are nonpolar molecules.

Applying the "similar compatibility principle" here, it can be understood that activated carbon has strong adsorption on nonpolar gases and nonpolar impurities, but weak adsorption on polar molecules such as water. (The adsorption of polar molecules by activated carbon is mainly through polar bonds on the surface of activated carbon)

3. Water molecules in aqueous solution have a very special property: hydrogen bond. Water molecules combine with each other through hydrogen bonds, and the strength of hydrogen bonds is very strong; Water molecule-water molecule force >; > activated carbon-water molecule force.

4. The activated carbon is placed in the aqueous solution, and the water molecules attract each other through hydrogen bonds, so that the nonpolar impurity molecules are relatively isolated from the activated carbon; Activated carbon can reduce the excess free energy on the surface by adsorbing impurity molecules. (The molecules in activated carbon are subjected to forces from all directions, and the forces are balanced; However, C molecules on the surface of activated carbon are only subjected to internal force, which is unbalanced and the resultant force points inward. Therefore, activated carbon tends to absorb external molecules to balance internal forces, so nearby molecules are enriched on the surface of activated carbon. )