Photocatalytic degradation of drugs by supported titania-based catalysts produced from petrochemical plant residue William Leonardo da Silva a , Marla Azário Lansarin a , Paolo Roberto Livotto b , João Henrique Z. dos Santos b, ⁎ a Departamento de Engenharia Química, Universidade Federal do Rio Grande do Sul, Rua Eng. Luis Englert s/n, 90040-040 Porto Alegre, RS, Brazil b Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves no 9500, 91501-970 Porto Alegre, Brazil abstract article info Article history: Received 31 October 2014 Received in revised form 5 February 2015 Accepted 29 March 2015 Available online 7 April 2015 Keywords: Pharmaceuticals Titania Catalyst residue Photocatalysis Waste A series of eleven drugs, namely, atorvastatin calcium, diclofenac sodium, fluoxetine, ketoconazole, ibuprofen, dexamethasone, tioconazole, naphazoline hydrochloride, valsartan, guaifenesin and paracetamol, were compar- atively degraded under UV and visible radiation in the presence of a supported photocatalyst generated from the catalyst residue from a Ziegler–Natta catalyst petrochemical plant. The presence of Mg (4.4%) and Ti (2.5%) afforded a catalyst that was active over the UV and visible spectral regions. For comparative reasons, commercial P25 (titania) was also evaluated. Among the tested systems, the highest drug degradation was observed under UV (48.6%) and visible (45.2%) radiation with the synthesized photocatalyst, whereas under the same conditions, the commercial P25 catalyst achieved 66.3% and 50.2% degradation, for UV and visible radiation, respectively. Despite the comparable degradation capability, the proposed photocatalyst could be reused five times without losing catalyst activity. © 2015 Elsevier B.V. All rights reserved. 1. Introduction A wide variety of pollutants have been found in aquatic environ- ments, such as effluent from sewage treatment plants and surface waters. Among these pollutants, compounds identified as emerging contaminants include certain drugs of different classes, such as analge- sics, anti-inflammatory drugs, psychiatric drugs, antibiotics and antilipemics, which may be present in wastewater, especially in the case of hospital effluents. There have been certain reports of the presence of emerging pollutants in water sources in several countries [1–5]. Pharmaceutical compounds have been detected in environmental samples, and concentrations at the ng L -1 and mg L -1 levels have already been reported [6]. The absence of appropriate treatment processes combined with the diversity of these contaminants found in domestic and industrial efflu- ents created demand for the development of new treatment methods to ensure efficient removal of these emerging pollutants. Many of these contaminants are not removed by conventional water treatment systems; therefore, they can cause irreversible damage to human health. Physical processes (i.e., sedimentation, flotation, filtration, and adsorption) are characterized by phase transfer of the contaminant without causing its degradation. These processes tend to be relatively efficient and may be useful as pre-or post-treatment steps [7–9]. Chem- ical processes are based on the oxidation of contaminants by reactions with strong oxidants, such as hydrogen peroxide (H 2 O 2 ), chlorine (Cl 2 ), chlorine dioxide (ClO 2 ) and permanganate (MnO 4 - ). However, in most cases, the use of this type of treatment does not result in the complete mineralization of the contaminant to CO 2 , with the formation of a wide variety of degradation by-products, particularly organic acids (oxalic, tartaric, formic, and acetic acid). The presence of substances in wastewater is a reflection of the low efficiency of their removal by conventional treatment processes, which leads to contamination of surface waters. This situation has en- couraged the search for more efficient methods capable of promoting mineralization of these contaminants or at least their transformation into products without adverse environmental effects. In this context, the Advanced Oxidation Processes (AOPs) have attracted significant in- terest due to their potential alternative or complementary approach to conventional sewage treatment processes. AOPs are processes based on the formation of hydroxyl radicals (HO•), which are highly oxidizing agents that can react with a wide variety of classes of compounds [10]. Among the AOPs, it is worth highlighting heterogeneous photocatalysis, which is a process involving redox reactions induced by radiation on the surface of a semiconductor (catalysts). In parallel, industrial activities have generated increasing amounts of solid waste, including inorganic materials, which are generally fated for landfills and function as another type of pollutant. Conventionally, the removal of metals from industrial wastes has been performed using cer- tain approaches, such as biological treatment techniques, liquid–liquid extraction, precipitation, reverse osmosis, activated carbon adsorption and reduction to an elemental form. These techniques often use poten- tially dangerous or polluting materials, and most of these techniques are Powder Technology 279 (2015) 166–172 ⁎ Corresponding author. Tel.: +55 51 3316 7238; fax: +55 51 3316 7304. E-mail address: jhzds@iq.ufrgs.br (J.H.Z. dos Santos). http://dx.doi.org/10.1016/j.powtec.2015.03.045 0032-5910/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec