Mechanochemical Modification of Activated Carbon in Air

The effect exerted on the chemical properties and structure of activated carbon by the mechanical treatment as a modification procedure was studied. Mechanochemical modification of carbon samples was performed in a roller–ring vibration mill for 5 to 30 min. Samples were studied by X-ray diffraction, IR spectroscopy, and low-temperature nitrogen adsorption. X-ray diffraction analysis shows that the supply of mechanical energy increases the extent of structural disordering of activated carbon, which is manifested in an increase in microstrains. The mechanical treatment for more than 5 min led to a decrease in the specific surface area of the samples with a simultaneous increase in the total pore volume. The mechanical treatment for 5 min and less led to an increase in the specific surface area and to a decrease in the pore volume. The results of potentiometric titration and Boehm titration show that the modification leads to an increase in the concentration of phenolic and carboxyl groups. It is concluded that mechanochemical modification of activated carbon in air leads to its intense oxidation resulting in formation of oxygen-containing groups and in their decomposition.