ORIGINAL PAPER Diamond cylindrical anodes for electrochemical treatment of persistent compounds in aqueous solution Hudson Zanin • Reinaldo F. Teo ´filo • Alfredo C. Peterlevitz • Ulisses Oliveira • Juliana C. de Paiva • Helder Jose ´ Ceragioli • Efraim L. Reis • Vitor Baranauskas Received: 25 July 2012 / Accepted: 8 October 2012 / Published online: 21 October 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Boron-doped diamond (BDD) films were deposited onto either silicon or niobium cylindrical sub- strates with areas up to 35 cm 2 for electrochemical appli- cations. BDD electrodes were characterised in terms of their material and electrochemical properties by scanning electron microscopy, Raman spectroscopy and linear sweep voltammetry. These characterisation techniques indicated conductive polycrystalline BDD with low quan- tities of non-diamond carbon impurities. Electrochemical oxidations of pharmaceutical compounds were performed using these cylindrical electrodes and monitored by UV/ Vis spectroscopy, chemical oxygen demand and total organic carbon. Mixtures of chlortetracycline, oxytetracy- cline and diclofenac were electrolyzed on a 9.42 cm 2 ([ = 6 mm, h = 50 mm) cylindrical Si/BDD anode using a current density of 8.2 mA cm -2 . Ibuprofen was electro- lyzed on an 18.0 cm 2 ([ = 10 mm, h = 60 mm) cylin- drical Nb/BDD anode using a current density of 25 mA cm -2 . Cylindrical-shape diamond electrodes pres- ent several advantages with respect to conventional plate- shape BDD electrodes such as handling, sealing and cell assembly. The obtained results show that BDD cylindrical anodes are promising for electrochemical wastewater treatment. Keywords Cylindrical diamond electrode Á BDD Á Diamond anode Á Electrochemical oxidation Á Micro-pollutants Á Chemical vapour deposition 1 Introduction One environmental problem facing humanity is the increasing pollution of freshwater systems by chemically active substances [1]. Many studies have documented the presence of drugs, pesticides, dyes and many other toxic compounds in rivers, lakes, groundwater and other sources of water [1–3]. Some of these pollutants are persistent in conventional drinking-water treatments (DWT), causing considerable toxicological concern, particularly when they form complex mixtures [1–4]. According to Schwarzenbach et al. [1], there are three challenges that must be met: (i) development of new methodologies to assess the impact of these pollutants on aquatic life and human health (ii) minimization of the introduction of critical pollutants into the aquatic system through more environmentally healthy products and pro- cesses, and (iii) the new cost-effective and appropriate remediation of water-treatment technologies. Advanced oxidation processes (AOP) have been studied to degrade recalcitrant compounds in water. However, the by-products generated by AOP may cause more serious problems for human health and the environment [5, 6]. The selection of treatment depends on the optimal control, reliability, cost-effectiveness and efficiency (oxidative and economic) being considered. Electrochemical oxidation is considered one of the most promising techniques for wastewater treatment [7–11]. H. Zanin Á A. C. Peterlevitz Á H. J. Ceragioli Á V. Baranauskas Departamento de Semicondutores, Instrumentos e Foto ˆnica, Faculdade de Engenharia Ele ´trica e de Computac ¸a ˜o, Universidade Estadual de Campinas, Campinas, SP 13083-852, Brazil R. F. Teo ´filo (&) Á U. Oliveira Á J. C. de Paiva Á E. L. Reis Departamento de Quı ´mica, Universidade Federal de Vic ¸osa, Vic ¸osa, MG 36570-000, Brazil e-mail: rteofilo@gmail.com 123 J Appl Electrochem (2013) 43:323–330 DOI 10.1007/s10800-012-0491-4