Original research article Synergism between anodic oxidation with diamond anodes and heterogeneous catalytic photolysis for the treatment of pharmaceutical pollutants Juan M. Peralta-Hern  andez a, * , Catalina de la Rosa-Ju  arez b , Vianey Buzo-Mu ~ noz b , Javier Paramo-Vargas b , Pablo Ca ~ nizares-Ca ~ nizares c , Manuel A. Rodrigo-Rodrigo c a Department of Chemistry, University of Guanajuato, Guanajuato 36040, Mexico b Department of Research and Graduate Studies, Center for Applied Innovation in Competitive Technologies, Le on 37545, Mexico c Department of Chemical Engineering, University of Castilla-La Mancha, Ciudad Real 13071, Spain article info Article history: Received 27 February 2015 Received in revised form 10 September 2015 Accepted 5 November 2015 Available online 12 April 2016 Keywords: Anodic oxidation Heterogeneous catalytic photolysis Diclofenac Acetaminophen Boron-doped diamond Titanium dioxide abstract The mineralization of diclofenac and acetaminophen has been studied by single anodic oxidation with boron-doped diamond (AO-BDD) using an undivided electrolysis cell, by single heterogeneous catalytic photolysis with titanium dioxide (HCP-TiO 2 ) and by the combination of both advanced oxidation pro- cesses. The results show that mineralization can be obtained with either single technology. The type of functional groups of the pollutant does not influence the results of the single AO-BDD process, but it has a significant influence on the results obtained with HCP-TiO 2 . A clear synergistic effect appears when both processes are combined showing improvements in the oxidation rate of more than 50% for diclo- fenac and nearly 200% for acetaminophen at the highest current exerted. Results obtained are explained in terms of the production of oxidants on the surface of BDD (primarily peroxodisulfate) and the later homogeneous catalytic light decomposition of these oxidants in the bulk. This mechanism is consistent with the larger improvement observed at higher current densities, for which the production of oxidants is promoted. © 2016 Chinese Institute of Environmental Engineering, Taiwan. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction In recent years, a large number of research groups around the world have conducted investigations on the detection and removal of pharmaceutical compounds, such as analgesics, anti- inflammatories, anti-microbials, antiepileptics, beta-blockers, es- trogens and lipid regulators, typically found as emerging pollutants in surface water, ground water (including drinking water) and in- dustrial wastewaters at concentrations ranging from a few mgL 1 to several mg L 1 [1e3]. In developing countries, such as Mexico, the management of these pollutants is not regulated and, therefore, they are continuously discharged into the environment without any treatment. Consequently, they do not undergo any significant degradation in industrial wastewater treatment facilities or in conventional urban wastewater treatment plants. Diclofenac and acetaminophen are two common drugs used to treat various diseases in human beings. Diclofenac (sodium salt (2- [2-(2,6-dichlorophenyl) aminophenyl] acetate ion)), is one of the most common non-steroidal anti-inflammatory drugs. It is widely used for controlling renal colic and protecting against recurrent urinary calculi, and it is also present in numerous pharmaceutical preparations to treat other various diseases. As a result of its resistance to biodegradation, it is one of the pollutants most frequently detected in groundwater, rivers and lakes around the world with concentrations in the environment as high as 4.4 mgL 1 [4e6]. Acetaminophen (paracetamol), N-(4-hydroxyphenyl) acet- amide is a drug with analgesic properties. It inhibits the synthesis of prostaglandins, cellular mediators responsible for the onset of pain. It also has antipyretic effects. It is usually presented in the form of capsules, tablets, suppositories or oral drops. In the search for efficient ways to remove these pollutants, several technologies have been used, highlighting the electro- chemical processes, such as electro-oxidation, also known as * Corresponding author. E-mail address: juan.peralta@ugto.mx (J.M. Peralta-Hern andez). Peer review under responsibility of Chinese Institute of Environmental Engineering. Contents lists available at ScienceDirect Sustainable Environment Research journal homepage: www.journals.elsevier.com/sustainable- environment-research/ http://dx.doi.org/10.1016/j.serj.2015.11.003 2468-2039/© 2016 Chinese Institute of Environmental Engineering, Taiwan. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Sustainable Environment Research 26 (2016) 70e75