N-modified TiO sub(2) photocatalytic activity towards diphenhydramine degradation and Escherichia coli inactivation in aqueous solutions

• Published in: Applied catalysis. B, Environmental Vol. 130-131; pp. 66 - 74
• Main Authors: Monteiro, Ricardo AR, Miranda, Sandra M, Vilar, Vitor JP, Pastrana-Martinez, Luisa M, Tavares, Pedro B, Boaventura, Rui AR, Faria, Joaquim L, Pinto, Eugenia, Silva, Adrian MT
• Format: Journal Article
• Language: English
• Published: 01-02-2013
• Subjects: Escherichia coli
• ISSN: 0926-3373
• DOI: 10.1016/j.apcatb.2014.06.017

Nitrogen modified TiO sub(2) samples were prepared by grinding the benchmark TiO sub(2) photocatalyst (P25, Evonik Degussa Corporation) with different amounts of urea and applying calcination temperatures between 340 and 420 degree C. Several characterization techniques, including X-ray photoelectron spectroscopy (XPS), N sub(2) porosimetry, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and diffuse reflectance UV-vis spectroscopy (UV-DRS), were used to obtain information about the morphology, crystalline phases of TiO sub(2) and chemical binding of nitrogen. Nitrogen modification did not affect the crystalline phase of TiO sub(2) as far as XRD analysis concerns; on the other hand the modified materials developed an absorption in the visible part of the electromagnetic spectrum. The material with a urea:TiO sub(2) weight ratio of 1:2, calcined at 380 degree C, exhibited the highest photocatalytic activity under visible light illumination ( lambda > 430 nm), towards degradation of diphenhydramine, an emerging water pollutant of pharmaceutical origin. The measured band gap energy of the material was 2.99 eV, which is in-line with observed optical absorption properties. In addition, this photocatalyst was also the most efficient for complete inactivation of Escherichia coli in aqueous solution when ultraviolet radiation ( lambda = 365 nm) was used. From the XPS analysis on the chemical states of this photocatalyst it is concluded that nitrogen is interstitial to the TiO sub(2) structure.