Ozonation of naphthalenetrisulphonic acid in the presence of activated carbons prepared from petroleum coke

The objective of this work was to analyze the activity of petroleum coke and of activated carbons prepared from this material in the ozonation of aromatic contaminants of low biodegradability. 1,3,6-Naphthalenetrisulphonic acid (NTS) was selected as model compound for the study. The presence of the original coke during 1,3,6-naphthalenetrisulphonic acid ozonation produced a slight increase in the NTS degradation rate, indicating the generation of highly oxidant species in the medium. The coke was chemically activated with KOH. The activation process considerably develops the micro-, meso- and macroporosity of the raw material. The surface chemical nature of the original coke was also modified by the activation process, increasing its surface basicity. The coke activation increased its activity in the NTS ozonation process due to: (i) development of the porosity of the coke, allowing greater accessibility of the ozone to its surface active sites and mineral matter and (ii) an increase in the surface basicity of the original material. The presence of either the original or activated coke reduces the concentration of total dissolved organic carbon (DOC) during NTS ozonation. This reduction is due to: (i) mineralization of organic carbon to CO2 because of the generation of OH radicals enhanced by the presence of the coke in the system (catalytic contribution), and (ii) adsorption of NTS oxidation by-products on the coke samples (adsorptive contribution).