Self-cleaning of modified cotton textiles by TiO2 at low temperatures under daylight irradiation

Photoinduced decolorization of 2, 6-dichloroindophenol by 2-anthraquinone sulfonate treated nylon

Photoactive 2-anthraquinone sulfonate sodium (2-AQS) can produce hydroxyl radical and other reactive oxygen species under UVA irradiation. Because of its acid dye like feature, 2-AQS was immobilized onto nylon fibers through an acid dyeing process, and the dyed nylon was employed as a photoactive self-cleaning material. As a model study, decolorization of representative colorants such as 2,6-dichloroindophenol (DCIP) by the material was investigated. The results revealed that DCIP was first absorbed on the fibers and then degraded by hydroxyl radicals and other reactive oxygen species generated by 2-AQS on the surfaces upon UVA exposure. The photo degradation pathway of DCIP was further studied by directly using aqueous 2-AQS solution, and the degraded products in the solutions were analyzed by LC-MS. Different light sources and hydrogen donors were investigated in degradation of DCIP. The photoactive functions on the 2-AQS-dyed nylon fibers were quite durable and maintained similar decolorization effect of DCIP after five repeated tests.

The fabrication of nanocomposite thin films with TiO2 nanoparticles by the layer-by-layer deposition method for multifunctional cotton fabrics

A multilayer nanocomposite film composed of anatase TiO(2) nanoparticles was fabricated on cationically modified woven cotton fabrics by the layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pre-treated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by a pad-batch method. Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to verify the presence of deposited nanolayers. Photocatalytic activities of the nanocomposite films were evaluated through the degradation of red wine pollutant. Nano-TiO(2) deposition enhanced the protection of cotton fabrics against UV radiation in comparison with the untreated cotton fabrics. Air permeability and whiteness value analysis was performed on the fabrics before and after the treatment with TiO(2) nanoparticles by the layer-by-layer deposition method. Tensile strength tests of the warp and weft yarns were performed to evaluate the effect of solution pH value changes during the alternate dipping procedures. For the first time the durability of the effect of the self-assembled multilayer films on the cotton fabric functional properties was analyzed after 10 and 20 washing cycles at 40 degrees C for 30 min.

Improved properties of oxygen and argon RF plasma-activated polyester fabrics loaded with TiO2 nanoparticles

The potentials of low-pressure capacitively coupled RF oxygen and argon plasmas for the activation of polyester fibers surface that can enhance the deposition of colloidal TiO(2) nanoparticles were discussed. SEM and XPS analysis confirmed the plasma-induced morphological and chemical changes on the surface of polyester fibers. Oxygen and argon plasma pretreated polyester fabrics loaded with TiO(2) nanoparticles provided maximum reduction of Gram-negative bacteria E. coli and UV blocking. The self-cleaning effects tested on blueberry juice stains and photodegradation of methylene blue in aqueous solution proved excellent photocatalytic activity of TiO(2) nanoparticles deposited onto fiber surface. Although both plasmas significantly contributed to overall improvement of properties of such nanocomposite textile material, oxygen plasma treatment, in particular, enhanced the deposition of colloidal TiO(2) nanoparticles and thus ensured superior effects.

Functionalization of a cotton fabric surface with titania nanosols: applications for self-cleaning and UV-protection properties

In this study, cotton fabric was successfully modified by titania nanosols prepared by means of the sol-gel process with tetrabutyl orthotitanate [Ti(OC(4)H(9))(4)] as the active ingredient. The cotton fabric was padded with the nanosol solution, dried at 60 degrees C, and cured at 150 degrees C. Scanning electron microscopy showed the presence of a titania film on the fiber surface. The photocatalytic properties of titania-nanosol-treated cotton fabric were investigated. The results showed that stains of coffee and red wine were successfully decomposed by exposure of the stained fabric to UV radiation. Furthermore, titania-nanosol treatment imparted to the cotton fabric a very good protection against UV radiation. The durability of the treatment was investigated by performing repeated home laundering, and the results showed no effect of laundering on the UV-protection efficiency.

Innovative UVC light (185 nm) and radio-frequency-plasma pretreatment of Nylon surfaces at atmospheric pressure and their implications in photocatalytic processes

Innovative pretreatment by UVC light (185 nm) and by radio-frequency (RF) plasma at atmospheric pressure to functionalize the Nylon surface, increasing its bondability toward TiO(2), is reported in this study. In the case of UVC light pretreatment in air, the molar absorption coefficient of O(2)/N(2) at 185 nm is very low and the air in the chamber absorbs very little light from the UVC source before reaching the Nylon sample. Nylon fabrics under RF plasma were also functionalized at atmospheric pressure because of the marked heating effect introduced in the Nylon by the RF plasma. This effect leads to intermolecular bond breaking and oxygenated surface groups in the topmost Nylon layers. Both pretreatments enhanced significantly the photocatalytic discoloration of the red-wine stain in Nylon-TiO(2) compared with samples without pretreatment. The UVC and RF methods in the absence of vacuum imply a considerable cost reduction to functionalize textile surfaces, suggesting a potential industrial application. Red-wine-stain discoloration under simulated sunlight was monitored quantitatively by diffuse-reflectance spectroscopy and by CO(2) evolution. X-ray photoelectron spectroscopy (XPS) was used to monitor the changes of the C, N, and S species on the Nylon topmost layers during the discoloration process. Significant changes in the XPS spectra of Ti 2p peaks were observed during discoloration of the wine spots. Wine stains attenuated the signal of the Ti 2p (458.4 eV) peak in the Nylon-TiO(2)-stained wine sample at time zero (from now on, the time before the discoloration process). Furthermore, a decrease of the wine-related O 1s signal at 529.7 eV and N 1s signal at 399.5 eV was observed during the discoloration process, indicating an efficient catalytic decomposition of the wine pigment on Nylon-TiO(2). X-ray diffraction detected the formation of anatase on the Nylon fibers. High-resolution transmission electron microscopy shows the formation of anatase particles with sizes between 8 and 20 nm.

Understanding photocatalytic behavior on biomaterials: Insights from TiO(2) concentration

We report the details of our success in conferring photocatalytic self-cleaning properties on keratin fibers using modified sol-gel colloids. To the best of our knowledge, we studied for the first time the crucial effect of the concentration of titanium dioxide precursor on colloid composition, properties, and biocompatibility in an attempt to enhance the properties and application of anatase titanium dioxide colloid to keratins. The transparency, the particle size distribution, and the crystallinity of synthesized colloids were systematically investigated. The compatibility of the colloids and keratin substrates is thoroughly compared and discussed. The insights presented contribute to the further understanding of the structure-property-use relationship of titanium dioxide in biomaterial applications.

Superhydrophobic cotton fabrics prepared by sol-gel coating of TiO2 and surface hydrophobization

By coating fibers with titania sol to generate a dual-size surface roughness, followed by hydrophobization with stearic acid, 1H,1H,2H,2H-perfluorodecyltrichlorosilane or their combination, hydrophilic cotton fabrics were made superhydrophobic. The surface wettability and topology of cotton fabrics were studied by contact angle measurement and scanning electron microscopy. The UV-shielding property of the treated fabrics was also characterized by UV-vis spectrophotometry.