Infoscience

Journal article

Grafted semiconductors on PE-films leading to bacterial inactivation: Synthesis, characterization and mechanism

This study reports the colloidal preparation FeOx, TiO2 and FeOx-TiO2 grafted on polyethylene (PE) films leading to bacterial inactivation. A fast bacterial inactivation was attained by the FeOx-TiO2 compared to the FeOx-PE film due to the interfacial charge transfer (IFCT) FeOx to the lower-lying TiO2 trapped states. A pH-decrease was observed during bacterial inactivation due to the formation of carboxylic acids on the grafted films and the recovery to the initial pH 7 after elimination of the intermediates was followed quantitatively during bacterial inactivation. The potential on the TiO2-PE, FeOx-PE and FeOx-TiO2-PE film surfaces decreased during the bacterial inactivation concomitant with the loss of the cell wall permeability. Different mechanisms for the photo-induced E. coil inactivation for random nanoparticulate FeOx-PE and FeOx-TiO2-PE films are suggested based on the experimental observations reported in this study. During the inactivation of E. coli, the Fe-ions were seen to leach out in amounts <= 0.45 ppm. This is within the EU sanitary allowed limits for industrial/drinking water. The wettability of the films was followed by contact angle measurements (CA) within the time of bacterial inactivation. By diffuse reflectance spectroscopy (DRS), the conversion of the Fe(III)-oxide to Fe(II)-oxide is reported during film recycling. The change in the Fe-oxidation states within the bacterial inactivation was further confirmed by X-ray photoelectron spectroscopy (XPS). (C) 2016 Elsevier B.V. All rights reserved.

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