Research Article Photodegradation of Polyphenols and Aromatic Amines in Olive Mill Effluents with Ni Doped C/TiO 2 Delia Teresa Sponza and Rukiye Oztekin Department of Environmental Engineering, Engineering Faculty, Dokuz Eyl¨ ul University, Tınaztepe Campus, Buca, 35160 ˙ Izmir, Turkey Correspondence should be addressed to Delia Teresa Sponza; delya.sponza@deu.edu.tr Received 24 October 2014; Accepted 13 January 2015 Academic Editor: Ronaldo F. do Nascimento Copyright © 2015 D. T. Sponza and R. Oztekin. 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. Magnetic nickel coated carbon based titanium dioxide [C/TiO 2 /Ni] nanocomposites were used for photodegradation of polyphenols and total aromatic amines (TAAs) metabolites from olive mill wastewaters (OMW) at diferent operational conditions such as diferent mass ratios of C, TiO 2 , and Ni (1%/2%/5%; 5%/1%/2%; and 2%/5%/1%), being at increasing photodegradation times (15, 30, 45, 60, 75, 120, and 180 min), photocatalyst concentrations (100, 250, 500, and 1000 mg L −1 ), pH values (3.5, 4.0, 7.0, and 10.0) and temperatures (15 ∘ C, 25 ∘ C, 50 ∘ C, and 80 ∘ C), and being under 300 W ultraviolet (UV) and 30 W sunlight irradiation. Under the optimized conditions, at pH = 7.0, at 500 mg L −1 C/TiO 2 /Ni nanocomposite, under 300 W UV light, afer 60 min, at 25 ∘ C, the maximum COD dissolved , total phenol, and TAAs removals were 99%, 90%, and 96%, respectively. Photodegradation removals in the OMW under sunlight and being lower than those under UV light. 1. Introduction Photocatalysis has been recognized as a potential technique for degradation process, which is being widely applied as one of the most efective methods for wastewater treatment [1]. For instance, it is widely applied as a useful technique for destruction of organic pollutants [2, 3]. TiO 2 semicon- ductor in anatase form is ofen used as photocatalyst for water purifcation from pollutants because of its stability, nontoxicity, and relatively satisfed activity [2, 3]. Te high surface area-to-volume ratio of TiO 2 nanoparticles, however, results in their aggregation [2, 3]. To improve the photo- catalytic activity of traditional TiO 2 , there are a variety of novel visible-light-responsive photocatalysts developed and those photocatalysts showed better catalytic activity [2, 3]. Meanwhile, doped TiO 2 photocatalysts [4, 5] and composite photocatalysts [6–8] were taken into consideration for the treatment of some dyes and pollutants [9]. TiO 2 -C hybrids are some of the most extensively investigated and most promising materials to improve the photocatalytic performance of TiO 2 because a variety of carbon materials can be tailor-made to meet the demands of TiO 2 as a photocatalyst [10]. In addition, the lightweight, nonpolar, nonreactive, and nontoxic nature of carbon materials and the easy separation of the materials from water are attractive in wastewater treatment [10]. In recent years, there has been growing interest in hybridizing carbon nanostructures such as carbon nanotubes (C) [8] and graphene [9, 10] with TiO 2 to enhance the photocatalytic performance. Te main purpose of carbon materials in the nanocomposite is to transfer photogenerated electrons from TiO 2 to suppress the recombination for efective charge separation [9]. Zhang [11] found that TiO 2 /Ni composites have the functions of both TiO 2 and Ni [11]. Te photocat- alytic and biocompatibility studies show that this TiO 2 /Ni composite remains the outstanding photocatalytic activity for organic pollutant decomposition and the biocompatibility of TiO 2 [11]. Lin et al. [12] investigated the hydrogenation of nitrobenzene in water by using Ni/TiO 2 catalyst. Tis catalyst has been used as an efective photocatalyst for decomposition of organic pollutants [11]. Pirkarami et al. [13] found 70% Reactive Red 19, 75% Acid Orange 7, and 74% Acid Red 18 removals with 30 mg L −1 Nano-Ni-TiO 2 photocatalyst at pH = 7.0 and 25 ∘ C. Shao et al. [10] studied the photocatalytic degradation of methylene blue (MB) dye with the addition Hindawi Publishing Corporation Journal of Chemistry Volume 2015, Article ID 276768, 12 pages http://dx.doi.org/10.1155/2015/276768