Activated carbon as catalyst of the ozone decomposition in highly oxidant species in aqueous phase

摘要

The present work aimed to study the ozonation of 1,3,6-naphthalenetrisulphonic acid (NTS), as a model contaminant, in the presence of different commercial activated carbons to enhance its degradation and removal. Results show that NTS was degraded by ozone at a faster rate in the presence of activated carbon, indicating the generation of species highly oxidants. The results obtained indicate that the activated carbon catalytic properties seem to be favoured by both the basicity of the carbon surface and the higher macropore volume. The high macroporosity in carbon reduces diffusion problems and, therefore, favouring access of the ozone to the active centres of the carbon surface, while the basal plane electrons and oxygenated surface groups of basic nature (chromene and pyrone) in activated carbons are mostly responsible for ozone decomposition in aqueous phase. The ozone reduction on the surface of activated carbon generated OH- ions and H2O2 that initiated the decomposition of ozone in aqueous phase into highly oxidative species. The total organic carbon (TOC) present in solution was reduced in the presence of activated carbon. This reduction is due to: I) mineralisation of organic matter to CO2 by highly reactive species catalysed by activated carbon and ii) the adsorption of oxidised by-products from NTS on activated carbon.