Photocatalytic properties and optical characterization of cotton fabric coated via sol-gel with non-crystalline TiO _2 modified with poly(ethylene glycol)

摘要

TiO _2 thin film coatings were realized on cotton fabrics by sol-gel technique using titanium iso-propoxide. The effect of different starting acidic solutions (nitric, hydrochloric and acetic acids) and the addition of poly(ethylene glycol) onto two different (0.25M and 0.025M) concentrations of TiO _2 have been widely investigated. The applications of the sol were performed by pad-dry-curing method at 120°C for 5min for curing condition. The microstructural, morphological and optical properties and the photocatalytic activity of the films were investigated. In particular, XRD analysis showed a thin film deposition without any crystalline structure, which was also confirmed by Tauc plot analysis with a band gap from 3.3 to 3.5eV. The photocatalytic activity assessment, evaluated by degradation of Procion red PX4B dyestuff, was carried out by visible and UV (365nm) sources. Under ultraviolet exposure condition the rate of degradation of pure TiO _2 films shows an interesting linear correlation with pKa of the acids used. Moreover, the PEG addition into mineral sol-gel solution dramatically increases the rate of dye degradation under exposure. Nevertheless, no significant changes in the mechanical properties were observed after 100h of UV and visible exposures.