【作者】 李协吉；

【导师】 尹光福；

【作者基本信息】 四川大学 ， 生物医学工程， 2005， 硕士

【摘要】 纳米TiO₂的化学性质比较稳定,且成本低、无毒,是最有应用潜力的一种半导体光催化剂。纳米TiO₂以其优异的光催化性能,在废水处理、空气净化、抗菌等环境卫生领域得到了广泛的应用,有着广泛的发展前景。纳米TiO₂在应用过程中存在不少的问题亟待解决,比如,催化剂的分散、催化活性以及固定化技术等都成为光催化技术实用化的主要制约因素。因此,提高纳米TiO₂的分散性能、催化活性和研究高效的负载技术都已成为目前研究的主要方向。 本论文的研究工作主要针对上述三个问题展开,首先通过采用直接沉淀法制备了纳米级锐钛矿型TiO₂和铅锌矿型ZnO粉体,通过对超声分散作用和pH值对粉体分散情况影响的探索后发现,长时间的超声振荡对纳米粉体—水体系的分散状况有决定性影响,分散体系的pH值对纳米粒子的分散稳定性能起主要作用。在pH=9.5左右,经过48小时的超声振荡,可使纳米TiO_2ZnO复合分散液达到最佳的分散及稳定效果,该体系对甲醛的降解率可达97%以上,且重复使用性能极好。 然后,将制得的纳米TiO₂复合分散液应用于降解经甲醛浸泡处理过的织物,模拟降解实际织物中残留的甲醛。工艺条件实验研究结果表明,催化剂用量增多,甲醛的降解效果也有所提高;最佳光照反应时间为5～6小时,既可以保证得到较高的甲醛降解率使织物中的甲醛含量符合国家标准,又不会由于光照时间过长引起织物老化;碱性条件下织物甲醛的降解率较高,是由于加速生成的OH使得光催化反应正向移动;喷涂方式负载对纳米催化剂的降解效果优于浸渍方式;紫外光比近紫外光更易于被纳米催化剂吸收,且催化效率相对较高:随着光强的增大,纳米催化剂的催化速率增加,但过大的光强易于使得更多还原

【Abstract】 Titanium dioxide might be the most potential photochemical catalyst due to its cheapness, innocuity, and stability. Currently, nano-TiO₂ has been widely applied in the environmental health field for it excellent photochemical property, including effluent treatment, air purification and disinfection and so on. However, many technical matters in the application of nano-TiO₂ should have to be settled as soon as possible, such as the dispersion of the catalyst, the photo catalysis activity and the immobilization methods. So the dispersivity, photocatalysis activity, and immobilization methods would be the chief research topics.In this paper, many attentions were mostly focused on the problems mentioned above. At first, the nano-TiO₂ and nano-ZnO were prepared with the direct precipitation method. The effect of ultrasonic and pH value on the dispersion and stabilization of the suspension system were discussed. The results showed that lasting ultrasonic vibration was the decisive factor to the dispersion of system, and the pH value would greatly influence the stability of the suspension system. It was found that the degradation ratio of HCHO could be upward of 97% in the dispersed liquid at pH=9.5 under 48 hrs ultrasonic vibration, and the relatively steady degradation effects could be getten after reused for several times.Secondly, the nano-TiO₂ composited dispersion was applied in the degradation of residual formaldehyde in the fabric which has been soaked in formaldehyde solution to simulate the degradation of the residual formaldehyde in practical fibric. The results revealed the great influence of technique conditions on the degradation of formaldehyde. The increase of catalyst could shorten the degradation time, and itmade a high formaldehyde-degraded ratio within the optimal reaction time 5-6hrs. After photo-catalytic degradation, the remnant concentration of formaldehyde could be lower to the control regulated by the national standard; furthermore, the relative short degradation time could not lead the aging of fabric by irradiation. Under alkalescence, the degradation of formaldehyde in fabric was faster than others relatively, because the reaction of formaldehyde-degraded might be accelerated by the formation of -OH. The degradation efficiency of catalyst was higher by spraying than by dipping, and UV made a higher degradation of formaldehyde than Short-UV, because the UV could be easily absorbed by Nano-TiO2. With the increase of light intensity, photocatalysis rate increased, however, a light intensity over given range could lead fabric to be aged. Then, the nano-TiC>2 composited dispersion was applied in the degradation of the residual formaldehyde in the easy-care finishing solution and easy-care finishing fibric. The results confirmed that the residual formaldehyde in the easy-care finishing fibric could not be played down by this photocatalytic oxidation technique although the degradation was still carried on, because the instable resin would be continuous continuously decomposed with the degradation. This result would offer some valuable experiences for the following researchers.At last, Silica-sol was used as adhesive and PVA as aid- adhesive to immobilize photo-catalyst as the coating film. Synthetically considering the porperities of the films, the contents of catalyst, silica-sol and PVA should be respectively 50-70g/L, 15g/L and 2g/L in the dispension. The macro-capability and micro-capability performance of the film have been investigated. The result showed that this fim could meet the need of application due to its excellent performances such as photo-activity, heat-resistibility, water-resistibility, corrosion protection, adhesion, and aging-resistibility. This method immobilized catalyst under room temperature would play an important role in the application of the photocatalysis technique.更多还原