Activated carbon fibers as redox mediators for the increased reduction of nitroaromatics

Activated carbon fibers (ACFs) were used as redox mediators in the anaerobic chemical reduction of two model nitroaromatic compounds: 4-nitrophenol and 3-chloronitrobenzene. The effect of ACF chemical properties on the reduction of nitroaromatic compounds was measured by chemical oxidation of ACFs with 8 M nitric acid and thermal treatment at 700 °C under an inert atmosphere of hydrogen:helium (1:99%), before their use in batch experiments. The results show that ACFs are necessary to transform the nitroaromatic compounds to their corresponding aromatic amines, indicating the function of ACFs as redox mediators. Furthermore, the oxidation and thermal modification of ACFs clearly changes the redox properties of these materials, with the former being the better option to increase the concentration of quinone groups (1.68 times), and therefore the redox mediating capacity of ACFs (up to 1.38 times).