Ozonation of naphthalenetrisulphonic acid in the presence of activated carbons prepared from petroleum coke M. Sa ´nchez-Polo, J. Rivera-Utrilla * Departamento de Quı ´mica Inorga ´nica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain Received 16 February 2006; received in revised form 30 March 2006; accepted 8 April 2006 Available online 5 June 2006 Abstract 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 CO 2 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). # 2006 Elsevier B.V. All rights reserved. Keywords: Ozone; Petroleum coke; 1,3,6-Naphthalenetrisulphonic acid (NTS) 1. Introduction The bactericidal properties of ozone led to its use in the treatment of drinking waters, pioneered in Nice (France) at the beginning of the 20th century. Nowadays, because of the large amount of resources invested in the study of ozone as a purifying agent, its high capacity for degrading and reducing the toxicity of organic contaminants is well known [1–3]. Ozone is widely used on a large scale in the treatment of drinking water but not in the treatment of industrial liquid residues, largely due to its high economic cost and the chemical complexity of the industrial effluents. However, the poor efficiency of conventional treatment processes in removing toxic organic compounds from industrial effluents to levels required by new environmental legislation has made ozone a highly attractive option for their treatment [1–3]. In order to increase the purifying efficacy of ozone and thereby reduce treatment costs, novel processes have emerged, known as Advanced Oxidation Processes (AOPs) [4–6]. They have proven efficient to increase the oxidation rate of a large number of organic and inorganic compounds and are generally based on a combination of UV radiation with strongly oxidant agents (ozone, hydrogen peroxide) or catalysts (semiconduc- tors) activated by UV radiation. Novel alternatives to traditional AOPs are currently under investigation, based on the addition of reactives to the system, generally heavy metals (Mn, Fe, Ni, Cu), thereby enhancing the effectiveness of the ozone as an oxidant [7,8]. However, the practical application of this methodology is not widespread, because of lack of knowledge on the reactions involved in the process and the need to add these metals to the system, thereby increasing the toxicity of some of them. Previous studies described the combined use of ozone and activated carbon in a single process as an attractive option for destroying toxic organic compounds [9–14]. Thus, it was observed that the capacity of activated carbons to produce www.elsevier.com/locate/apcatb Applied Catalysis B: Environmental 67 (2006) 113–120 * Corresponding author. Tel.: +34 958248523; fax: +34 958248526. E-mail address: jrivera@ugr.es (J. Rivera-Utrilla). 0926-3373/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.apcatb.2006.04.011