Nanocomposites of Titanium Dioxide and Peripherally Substituted Phthalocyanines for the Photocatalytic Degradation of Sulfamethoxazole.

Phthalocyanines (Pcs) are often used in photosensitization of titanium(IV) oxide, a commonly employed photocatalyst, as such an approach holds the promise of obtaining highly stable and efficient visible light-harvesting materials. Herein, we report on the preparation, characterization and photoactivity of a series of composites based on TiO 2 and peripherally modified metallophthalocyanines: either tetrasulfonated or 4,4',4'',4'''-tetraazaphthalocyanines, with either copper(II), nickel(II) or zinc(II) as the central metal ion. Physicochemical characterization was performed using UV-Vis diffuse reflectance spectroscopy, hydrodynamic particle-size analysis, surface-area analysis using N 2 adsorption-desorption measurements and thermogravimetry combined with differential scanning calorimetry. The band-gap energy values were lower for the composites with peripherally modified phthalocyanines than for the commercial TiO 2 P25 or the unsubstituted zinc(II) phthalocyanine-grafted TiO 2 . TG-DSC results confirmed that the chemical deposition, used for the preparation of Pc/TiO 2 composites, is a simple and efficient method for TiO 2 surface modification, as all the Pc load was successfully grafted on TiO 2 . The photocatalytic potential of the Pc/TiO 2 materials was assessed in the photocatalytic removal of sulfamethoxazole-a commonly used antibacterial drug of emerging ecological concern. To compare the activity of the materials in different conditions, photodegradation tests were conducted both in water and in an organic medium.