Positive adsorption - When there is a solution containing solute ions and solvent ions and the adsorbing material adsorbs the solute particles, then eventually concentration of the solute in the solution decreases compared to its initial concentration. This phenomenon is called positive adsorption.

Negative adsorption - When there is a solution containing solute ions and solvent ions and the adsorbing material adsorbs the solvent molecules, then the concentration of the solvent molecules interacting with the adsorbing material increases compared to the initial condition. This phenomenon is called negative adsorption.

Physical adsorption - is a phenomenon where there are no chemical bonds formed between the adsorbate and the adsorbing material.

Chemical adsorption - is a phenomenon where the adsorbate is attached through chemical linkages on the surface of the adsorbing material.