Kinetics and mechanism for transparent polyethylene-TiO2 films mediated self-cleaning leading to MB dye discoloration under sunlight irradiation

Polyethylene-TiO2 (from now on PE-TiO2) transparent, non-scattering sputtered films have been found effective in the discoloration of methylene blue (MB) under low intensity solar simulated light. By Fourier transform attenuated infrared spectroscopy (ATR-FTIR), the systematic shift and decrease in the nu(s)(CH2) and nu(s)(C=C) vibration-rotational bands was observed preceding MB discoloration. RF-pretreatment allowed a significant increase in the TiO2 loading on PE compared to non-pretreated PE as shown by X-ray fluorescence (XRF). The PE-TiO2 photo-switching from a hydrophobic to a hydrophilic surface was observed within 60 min under light while the reverse process was complete within 24h in the dark. The position of the MB* and MB*/MB+ levels allowing electron injecting into the TiO(2)cb is discussed. The probability for the MBT deactivation and of MB* reacting with O-2 leading to the short lived MB+ cation is estimated. A mechanism for MB discoloration on PE-TiO2 is suggested. (C) 2014 Elsevier B.V. All rights reserved.


Published in:
Applied Catalysis B-Environmental, 162, 236-244
Year:
2015
Publisher:
Amsterdam, Elsevier Science Bv
ISSN:
0926-3373
Keywords:
Laboratories:




 Record created 2015-02-20, last modified 2018-03-17


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