Research Article Catalytic Ozonation of Phenolic Wastewater: Identification and Toxicity of Intermediates Mahdi Farzadkia, 1 Yousef Dadban Shahamat, 2 Simin Nasseri, 3 Amir Hossein Mahvi, 3 Mitra Gholami, 1 and Ali Shahryari 2,4 1 Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran 2 Environmental Health Research Center, Golestan University of Medical Sciences, Gorgan 4918936316, Iran 3 Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 4 Department of Environmental Health Engineering, Environment Research Center, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran Correspondence should be addressed to Yousef Dadban Shahamat; ydadban@yahoo.com Received 18 December 2013; Revised 5 March 2014; Accepted 11 March 2014; Published 6 May 2014 Academic Editor: Jong M. Park Copyright © 2014 Mahdi Farzadkia et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A new strategy in catalytic ozonation removal method for degradation and detoxifcation of phenol from industrial wastewater was investigated. Magnetic carbon nanocomposite, as a novel catalyst, was synthesized and then used in the catalytic ozonation process (COP) and the efects of operational conditions such as initial pH, reaction time, and initial concentration of phenol on the degradation efciency and the toxicity assay have been investigated. Te results showed that the highest catalytic potential was achieved at optimal neutral pH and the removal efciency of phenol and COD is 98.5% and 69.8%, respectively. First-order modeling demonstrated that the reactions were dependent on the initial concentration of phenol, with kinetic constants varying from 0.038 min −1 ([phenol] o = 1500 mg/L) to 1.273 min −1 ([phenol] o = 50 mg/L). Bioassay analysis showed that phenol was highly toxic to Daphnia magna (LC 50 96 h = 5.6 mg/L). Comparison of toxicity units (TU) of row wastewater (36.01) and the treated efuent showed that TU value, afer slightly increasing in the frst steps of ozonation for construction of more toxic intermediates, severely reduced at the end of reaction (2.23). Tus, COP was able to efectively remove the toxicity of intermediates which were formed during the chemical oxidation of phenolic wastewaters. 1. Introduction phenol is a hazardous contaminant and classifed as a toxic and priority hazardous contaminant in the list of USEPA [1], which can be found in aqueous efuents from various indus- tries such as the petrochemical plants, petroleum refneries, manufacturing of resins and plastics, steel production, coal conversion, surface runof from coal mines, dyestuf, tanning, paint stripping operations, pulp and paper, pesticides, phar- maceuticals, medications, and food processing industries [2, 3]; Environmental Protection Agency has limited this contaminant concentration in surface waters to less than 1 ppb [4]. Due to its toxicity and hazardous character and an increasing social concern on environment, it is required to be removed prior to discharging to the environment. Terefore, because the traditional methods of treatment of phenolic wastewaters such as physical and biological processes are not sufcient and have their own limitations, there is a need to use efective strategies of treatment. Many investigations are available regarding the use of advanced oxidation processes (AOPs) such as ultrasonic, photooxidation, photocatalytic oxidation plasma, Fenton, photo-Fenton, wet oxidation, and ozone/ultraviolet (UV) for the degradation and mineralization of various classes of biorecalcitrant organic compounds [5] that, based on economic consideration and their complexity, rarely selected as a possible process. Ozonation is one of the oxidation processes widely used for industrial wastewater pretreatment in which ozone molecules (as a strong oxidant) break down recalcitrant and Hindawi Publishing Corporation Journal of Engineering Volume 2014, Article ID 520929, 10 pages http://dx.doi.org/10.1155/2014/520929