| It is difficult to control the growth of nano TiO2which is likely to aggregate owing to its small grain size, specific surface, high surface energy and special surface structure. Hence, it is not stable in aqueous phase and other mediums. In addition, high temperature processing of over300℃is generally adopted to prepare TiO2so as to obtain well-crystallized thin film, which is unbearable for flexible textiles.Therefore, the extensive application of nano TiO2on textiles depends on how to well distribute nano particles in the mediums, obtain well-crystallized thin film, and avoid the influence of high temperature on textile, and control the growth TiO2as well as combination of nano particles and textile fibers. To solve the above-mentioned questions, the paper systematically did research and analysis of low temperature preparation and crystallization of nano TiO2, thermal crystallization treatment, doping modification, composite multi-functional treatment of textiles, and assessment of photo-catalytic performance. The major studies and innovations included:1. Low Temperature Preparation and Crystallization of Nano TiO2HydrosolNano TiO2hydrosols were prepared via sol-gel method with excessive water at low temperature. Nano TiO2powder or TiO2film with high crystallinity and high catalytic activity were obtained by low-temperature steaming and thermal crystallization. The effects of water amount, pH value, dropping sequence of reagents, thermal crystallization, etc. on low temperature crystallization of nano TiO2were discussed and analyzed. It was indicated that when the mole ratio of TBOT and water was more than1:100and TiO2sol was treated by steaming at100～120℃, TBOT could be completely hydrolyzed and more perfect powder crystal was obtained with high quantity, small size and favorable photo-catalytic performance. This low-temperature crystallization didn’t need high-temperature sintering, and the obtained nano TiO2can be coated on substrates that can not withstand high temperature, thus broadening the application field of nano-TiO2.2. Synergistic Effect of Metal and Non-metal Ions and Nano TiO2HydrosolBy doping metal and non-metal ions into lattice of TiO2, crystallization of TiO2was affected, which shortens the band gap of TiO2, affects the combination of photo-production of electron and hole, stimulates its photo-catalysis under visible light and broadens the range of photo response. The iron, silver, nitrogen, carbon, etc. were used as doping elements and how to dope ions into nano TiO2to prepare doped nano TiO2by sol-gel method was explored. Thus, the photo-catalytic activity of TiO2was improved due to their synergistic effect and photo-catalysis and spectral response range were improved.Compared with the undoped TiO2, doped TiO2had a favorable degradation effect on Methylene Blue and photo-catalytic activity of TiO2after doping depended on the features and density of doping ions. The fabrics treated by the doped nano-TiO2had excellent UV resistance and antibacterial effects3. Preparation of Nano TiO2/ZnO Composites and its effect on Photo-catalysisNano ZnO was adopted to modify nano TiO2. Direct mixing method and fractional precipitation method were adopted to prepare TiO2/ZnO composite powder with the mole ratio of9:1. The differences between the structures and performances of nano composites prepared by two different methods were compared and their photo-catalytic activity together with self-cleaning performance under UV, UV-visible light, and visible light were analyzed as well. As for nano TiO2/ZnO composites, Zn2+as electron acceptor strived for more electrons, restraining the combination of electrons and holes on the surface of the composites, resulting in the appearance of more O2-and·OH on the surface of composites, and improving the decomposition of organics. The results showed that red shift occurred in the UV absorbency band of nano TiO2/ZnO composites and band-gap energy decreased, so the TiO2/ZnO composites had photo-catalytic activity under visible lights. Furthermore, the fabrics treated by TiO2/ZnO complexes had excellent photocatalytic self-cleaning properties in the sun.4. Growth Control of Low-temperature Prepared Nano TiO2and Research on Multi-functional Treatment TechnologyThe low-temperature prepared nano TiO2hydrosols were applied on cotton fabrics. The effects of different treatment methods on growth control and dispersive uniformity of nano TiO2were analyzed, and the treated cotton fabrics had excellent performances like anti-UV, anti-bacteria, self-cleaning, degrading VOC, etc. The research showed that the novel steaming treatment could control the growth of TiO2and hydrolysis reaction without dispersant, and the nano particles could be uniformly dispersed on cotton fabrics. Compared with traditional baking and hydrothermal technology, the crystallization intensity of nano TiO2particles prepared by steaming treatment were much higher. The nano particles could be firmly bonded with fiber without obvious influence on physicochemical performance of textile, which prevented fiber from cracking.Moreover, to further improve durability of the treated textiles, plasma pre-treatment was carried out on the surface of cotton fiber, which produces functional groups on fiber surface like C=O,-COOH, CH2-OH, etc. Such groups could be well-bonded with TiO2, improving the bonding of fiber and TiO2effectively. So the treated textiles had durable multi-functions.The paper develop the on-line detecting VOC test chamber and the on-line VOC detecting system was composed of special sensor, basic evaluation appliance, data programming, on-line detecting appliance, etc. The system with reliable data and short period could carry out real-time detection of TVOC on cotton fabrics. Compared with traditional chromatogram, it could test and record detection data continuouly, its speed is more than10times and it could be monitored qualitatively and quantitatively. |
PDF Full Text Request