【作者】 王芳；

【导师】 陈港；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2010， 硕士

【摘要】 室内空气污染已成为一个普遍关注的问题,而最近几十年发展起来的光催化技术则成为了解决该问题的重要方法。本实验以具有吸附能力的活性炭纤维作为载体,将纳米TiO2通过湿部添加或者浸渍等方式,制成了具有纸页结构和高光催化活性的纸张,以期为光催化纸张的进一步研究提供理论基础。首先利用电阻式半导体VOC传感器设计了一组简单的能直接读取甲醛浓度的光催化装置。该装置首先保证了气密性良好,其次传感器检测时较稳定,灵敏度较高。通过检测发现,传感器灵敏度和甲醛浓度呈现的是反对数关系,且绘制的标准曲线线性关系良好。用湿部添加纳米TiO2的方法所抄造的光催化纸张,考察其与纸张中活性炭纤维的协同作用。单独活性炭纤维、纳米TiO2光催化纸、活性炭纤维/纳米TiO2光催化纸第一次、第二次使用时甲醛气体降解率(或吸附率)依次是65%/15%,80%/80%,90%/89%,活性炭纤维和纳米TiO2同时使用时有效地克服了活性炭纤维的饱和现象,而且提高了单独TiO2纸的降解率。用30%、35°SR的北木纤维配抄,活性炭纤维:TiO2为1:2,6%的胶乳增强剂以及0.15%PEI/0.2%APAM助留剂抄造的活性炭纤维/TiO2光催化纸张获得的抗张指数、TiO2留着率、透气度以及光催化效率最好,分别为4.7N·m/g、94%、2000mL/min、94%。制备较稳定的TiO2悬浮液,控制悬浮液pH<3.0或pH>9.5,超声分散时间15min,分散剂用量0.15%时的TiO2悬浮液平均粒径最小,分散性良好。然后用2%PPE作为湿强剂抄成活性炭纤维浸渍原纸。浸渍以后的光催化纸张,负载了6g/m2TiO2后反应210min的光催化效率达到了84%,相比于前一种湿部添加方法抄造的光催化纸负载44g/m2TiO2后反应210min的光催化效率是93%而言,具有负载量虽然较少但是光催化效率高的优点。SEM图观察到该浸渍纸的纳米TiO2非常均匀的附着在纤维表面,而湿部添加纸的TiO2则絮聚相对严重,且有部分填覆在活性炭纤维的沟槽内,两种附着方式的接触面积均较大。研究光催化纸使用时光催化剂的光催化活性、光源种类、光照强度、甲醛气体初始浓度以及环境湿度对光催化效率的影响,发现:光催化活性是保证光催化效率的关键;254nm紫外灯光催化效率好于365nm紫外灯的效果,而白炽灯几乎没有光催化作用,三种灯的甲醛降解效率依次是99%以上,99%,55%;随光照强度的增加,光催化效率的增长速率逐渐变缓;甲醛初始浓度较低时,满足零级反应方程,而浓度较高,则满足一级反应方程;当环境湿度为45%左右时的光催化效率最高。更多还原

【Abstract】 Over the past several decades, photocatalytic degradation of indoor volatile organic pollutants (VOC) by titanium dioxide (TiO2) had attracted much attention. In this paper, actived carbon fibers (ACF) were used as the nano-TiO2 carrier, and the ACF/TiO2 photocatalytic sheet was prepared by a papermaking technique in an attempt to offer technological and theoretical support for the research of photocalytic paper.A simple photocatalytic device to test formaldehyde concentration was designed using resistance-type semiconductor VOC sensor. This device not only had good air tightness, but also was stable and sensitive. The detection results showed that the sensor sensitivity and concentration of formaldehyde is presented inverse logarithm relationship.The synergistic effect of ACF and nano-TiO2 was tested, the results indicated that the first and second time using ACF sheet, TiO2 sheet and ACF/TiO2 sheet, the photocatalytic dagradation rate were 65%/15%, 80%/80%, 90%/89%. We found that the ACF/TiO2 sheet could overcome the saturation of ACF sheet and increase the degradation rate of TiO2 sheet. With 30% and 35°SR softwood pulp, the ACF/TiO2 ratio of 1:2, 6% latex, 0.15% PEI and 0.2% APAM, the tensile index, retension rate of TiO2, air permeability and photocatalytic degradation rate can reach about 4.7N·m/g、94%, 2000mL/min, 94% respectively.To prepare stable TiO2 suspension in water, the optimal dispersion treatment parameters were as following: the pH<3.0 or pH>9.5, Ultra sonic dispersion time 15 min, amount of sodium hexametaphosphate 0.2%. And the ACF base sheet was prepared with 2% PPE to increase the wet strength. After dipping, the dipped sheet with 6g/m2 TiO2 can degrade 84% formaldehyde after 210 min. By the way, the TiO2 added in the wet-end sheet can degrade 93% formaldehyde after 210 min. The SEM images showed nano-TiO2 distributed uniform on the ACF about the dipped sheet, while the nano-TiO2 filled in the goove of ACF about the wet-end sheet, but both methods could improve the contact area.Some factors, such as the photocatalytic activity of photocatalyst, lamps, light intensity, concentration of formaldehyde, and humidity, were researched. And the results showed that the photocatalytic activity of photocatalyst is the key point to degrade formaldehyde efficiently; the degradation rate of 254nm, 365nm, and incandescent lamp were 99%, 99%, 55%, this means the incandescent lamp hardly photocatalytic degaraded formaldehyde; the increasing speed of photocatalytic degradation became slower and slower as increasing the light intensity; the lower concentration of formaldehyde was fit for zero order reaction, while the higher concentration was fit for first order reaction; the photocatalytic degradation rate was highest when the humidity remain about 45%.更多还原