The photocatalytic performance of a composite based on the association of TiO 2 and 2.5 wt.% of zinc(II) phthalocyanine (TiO 2 /ZnPc) was evaluated towards the mineralization of paracetamol and compared to that observed for the bare oxide in different pH and H 2 O 2 concentrations. The results show that the photocatalytic performances were influenced by the pH, with maximum efficiency around the isoelectric point. Mineralization efficiencies between 86-91% was obtained using TiO 2 /ZnPc in pH 5.5-6.8, with 33 mg L -1 of H 2 O 2 , ca. 15% higher than that observed with TiO 2 . The mineralization efficiencies using bare TiO 2 and TiO 2 /ZnPc were respectively 112 and 18% lower in the absence of H 2 O 2 . The better performance of TiO 2 /ZnPc is related to its extended light absorption and non-uniform coating of the TiO 2 surface by ZnPc aggregates. Above pH 6.8, the mineralization efficiencies decrease for both photocatalysts, although the consumption of H 2 O 2 remains above 90%, due to its decomposition in alkaline pH.Keywords: mineralization, paracetamol, heterogeneous photocatalysis, role of pH and hydrogen peroxide, TiO 2 /zinc(II) phthalocyanine nanocomposite IntroductionSince initial studies by Fujishima and Honda, 1 heterogeneous photocatalysis 2 has attracted considerable attention due to its many technological applications, such as H 2 production, 3-5 CO 2 reduction, 6-8 environmental remediation, 9-12 among others. TiO 2 has been widely used in heterogeneous photocatalysis due its low cost, low toxicity, chemical and photochemical stability, usually expressive photocatalytic activity and versatility. 2,10,12,13 Its main limitation as photocatalyst is related to the lack of absorption in the visible region, which limits its use under solar irradiation. Several strategies have been employed to overcome this limitation, including doping 3 and production of nanocomposites. 9,[12][13][14] TiO 2 -based photocatalysis has been specially used in environmental remediation for the removal of recalcitrant and hazardous organic pollutants in wastewater. 9,15 The radicals produced from its excitation by light are able to efficiently oxidize organic pollutants leading in some cases to a complete mineralization of the organic matter.Paracetamol (N-acetyl-p-aminophenol, PCT), Figure 1a, among other pharmaceutical products, their metabolites, pesticides, hormones and herbicides, 9,16-20 is calling attention due to its persistence in the environment and the inability of the sewage treatment plants in removing this contaminant, which may result in bioaccumulation and harmful consequences for ecosystems. 17,[20][21][22] Although PCT is metabolized mainly by the liver, up to 68% of this drug tends to be excreted in the urine when ingested within permitted levels. [21][22][23][24] It should be emphasized that one of the routes of paracetamol metabolism produces highly toxic metabolites able to bind covalently to cysteine present in proteins. 23,25Figure 1. Chemical structure of PCT (a) and Zn(II) phthalocyanine (b). França e...

Additional information is available at the end of the chapter http://dx.doi.org/10.5772/59602 . Introduction . . Titanium dioxide TiOTiO is a promisinμ material λor technoloμical applications λor its versatility [ -], abundance, low toxicity, μood chemical stability, photosensitivity and photostability [ -]. In nature, it is λound mainly in the mineral ilmenite [ ], that can be processed industrially by two diλλerent routes [ ] The λirst, involves the reaction oλ the concentrate oλ ilmenite with hot sulphuric acid, resultinμ in the λormation oλ sulphates oλ titanium, Fe II and Fe III , beinμ these last eliminated by centriλuμation, aλter coolinμ. The λinal solution is then puriλied and hydrolyzed to produce pure TiO [ ]. The other usual way oλ obtaininμ consists in combininμ the ore with coke and μaseous chlorine under heatinμ, resultinμ in CO and a sponμy material rich in TiCl . The reaction product is subjected to successive λractional distillation, with the λormation oλ TiCl and TiCl , due to stability oλ titanium in other deμrees oλ oxidation. The diλλerent precursors oλ titanium are hydrolyzed, λorminμ titanium dioxide [ ]. In, [ ], obtained, λor the λirst time, success in decomposition oλ water under irradiation with liμht and without application oλ any electric potential. They reported that, in trials where they employed n-type TiO as anode and Platinum as cathode, when TiO electrode illuminated under short-circuit conditions, hydroμen evolved λrom the Platinum electrode, while oxyμen evolved λrom the anode. Since then, studies aimed at discoverinμ and explorinμ diλλerent possibilities oλ technoloμical application λor TiO have been μiven μreat importance [ -].© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.As technoloμical applications λor TiO can be cited its use in ultraviolet radiation absorbinμ λilters [ , ], in chemical sensors λor μases [ -], as a bactericide [ ], in biomaterials λor bone implants [ ], in environmental photocatalysis [ , , , ], in the photocatalytic hydroμen evolution [ , -], in dye-sensitized solar cells [ , -], amonμ other.The photocatalytic eλλiciency oλ TiO depends on its structural and morpholoμical characteristics, which are related to the method oλ synthesis used in the preparation oλ nanoparticles [ , , , ]. To be photoactive, λavorinμ the photocatalysis process, besides beinμ mainly consistinμ oλ anatase crystalline phase, the TiO must possess hiμh speciλic surλace area, μood porosity, with hiμh sized pores [ , , ]. In this context, the search λor TiO particles that have diλλerentiated λeatures, with catalytic properties potentiated, constitutes a λield oλ intense activity [ , , -]. . Porosity and porous materialsThe porosity, related to the presence oλ cavities, channels or interstices is oλ μreat importance since it is related t...