Adsorption Mechanism of Strong Acids, Strong Bases or their Salts by Activated Carbon and pH of the Solution with Carbon Suspension

Abstract

Adsorptivity and adsorption mechanism of strong acids, strong bases or their salts by commercial activated carbon, which was made from bituminous coal by steam activation at 950°C, were investigated, and pH of the solution with carbon suspension was studied with various method.
Hydrogen ion and' anions are adsorbed equally in the adsorption of acids (Fig.1, Table 2), and they are adsorbed mainly by carbonium ion mechanism. Hydroxide ion and cations are adsorbed equally in the adsorption of bases (Fig.3, Table 3), and hydroxide ion seemed to react with acidic oxidized groups of carbon surface. Anions are peculiarly adsorbed and cations are adsorbed to an electric double layer in the adsorption of salts, and pH of the solution increased with adsorption of hydrogen ion (Fig.5, Table 4). The distilled water, which was boiled with carbon and was separated from it, is neutral, but is alkali'ne without separation because of the adsorption of chloride ion from pH electrode. The city water, which was boiled with carbon and was separated from it, is alkaline because of the adsorption of salts in city water (Fig.6).