Hydrogen ion concentration: The pH of a solution from which
adsorption occurs influences the extent of adsorption. Because, hydrogen and
hydroxide ions are adsorbed quite strongly, the adsorption of other ions is
influenced by the pH of the solution. The majority of colored materials
encountered with the industry are negatively charged and ordinarily carbons
will give greater decolourisation with increase in acidity of the solution, the
pH of the adsorbent itself is an important factor, as this may affect the pH of
the liquid.