OXIDATION OF ACTIVATED CARBON BY HYDROGEN-PEROXIDE - STUDY OF SURFACEFUNCTIONAL-GROUPS BY FT-IR

Outgassed activated carbon was oxidized using H2O2 aqueous solutions a nd the surface oxygen groups were identified by FT-i.r. spectroscopy. The influence of solution concentration and pH, outgassing and oxidati on conditions of the carbon, and the addition of catalytic or stabiliz er agents to the oxidizing solution was investigated. The stability of the surface groups was also studied for a series of samples. The surf ace groups initially present in the carbon were largely OH and C-O-C. Oxidation of material with H2O2 solution, at unchanged pH, increased t he OH groups present in the oxidized products. With solutions of pH 2. 5 and 11.5, the OH groups decreased and various oxygen groups such as C=O and C...O, or CO2-, were formed. At the lowest pH value, formation of C-O-C structures with an increased number of C-O bonds occurred. E ther structures were lost when outgassing under more drastic condition s and when contact with the oxidizing solution was established at very different temperatures. The addition of Fe2+ to the oxidizing solutio n favoured the oxidation of carbon. However, Fe3+, ethanol and ether w ere not effective agents. Significant changes in the surface chemistry of samples were observed after a long period of time.