【作者】 俞成林；

【导师】 康勇；

【作者基本信息】 天津大学 ， 化工过程机械， 2007， 硕士

【摘要】 本文以硫酸氧钛为原料、硅藻土微粒为载体,尿素为沉淀剂,通过改变硫酸氧钛浓度、硅藻土与二氧化钛质量比、尿素浓度、pH值、水解温度、反应时间和焙烧温度等工艺条件,采用混合均匀沉淀法制备出了硅藻土基负载型纳米二氧化钛。利用SEM和XRD对样品的结构性能进行测定,得出最佳制备条件为:硫酸氧钛浓度初始浓度0.01mol/L,硅藻土与TiO₂质量比为2:1,尿素浓度为0.1mol/L,反应体系pH值为1.5,水解温度为75℃,反应时间为60min,煅烧温度700℃。在上述条件下制备的硅藻土基纳米二氧化钛样品中二氧化钛在硅藻土表面的最大覆盖率为75%、二氧化钛平均粒径为150nm,并初步探讨了二氧化钛粒子和载体之间的结合机理。在最佳条件下制备的样品,做降解甲醛气体的效果实验,并以实际的环境条件为参考,改变反应器内甲醛气体的初始浓度、反应体系的温度、相对湿度和光照强度,用气相色谱定量测定甲醛气体的含量,得出结论:硅藻土基纳米二氧化钛能在光照下持续降解高浓度甲醛气体,初始浓度为6.0×10-3mg/L甲醛气体,用5g样品经过150小时降解率达到99%;用5g硅藻土基纳米二氧化钛处理初始浓度为2.0×10-3mg/L甲醛,15℃时,需要50小时将其完全降解,温度越高,所需要时间越短,45℃下仅需要12小时就能彻底降解;光照强度为0时,产品几乎不能降解甲醛,照度越大,降解速率越快,在8100Lm/m2的照度下,5g样品14小时能将浓度为2.0×10-3mg/L甲醛完全降解;相对湿度的大小也影响对甲醛气体的降解,5g样品在相对湿度50%下,14小时能将2.0×10-3mg/L的甲醛降解到3.72×10-5mg/L,相对湿度越大,降解越彻底,在相对湿度80%下,14小时能降到1.0×10-5mg/L。更多还原

【Abstract】 The nano-sized titanium dioxide immobilized onto diatomite was obtained through changing the TiOSO4 concentration, the quantity proportion between diatomite and TiO₂, the concentration of urea, pH, reaction temperature and time, calcining temperature by the mixed homogeneous deposition method using the carrier of diatomite,the raw material of TiOSO4 and the precipitator of urea The obtained photocatalyst were characterized by SEM and XRD and it was concluded that the best preparing conditions were as flowing: the incipient concentration of TiOSO4 was 0.01mol/L, the quantity ratio between diatomite and TiO₂ was 2:1, the concentration of urea was 0.1mol/L, the pH of reaction system was 1.5, the reaction temperature was 75℃, the reaction time was 60 min and the calcining temperature was 700℃. Under the best preparation conditions, the max loading rate of nano-sized titanium dioxide was 75%, and the average diameter of loaded particle was 150nm. We also probed to the binding mechanism of titanic dioxide particulate and the diatomite carrier.The experiment of degrading formaldehyde was did using the sample that was made out under the best preparation conditions.The residual quantity of formaldehyde was mensurated by the gas chromatograph through changing the raw concentration of formaldehyde injected into the reactor, the reaction temperature of reaction system, the light intensity and the relative humidity of atmosphere in the reactor on principle of the practical environment conditions. It came to the conclude as follows: the sample we made could oxidate completely the high concentration of formaldehyde under uninterrupted illumination and 5 gram of our sample could decrease 99 pensent of the formaldehyde with raw concentration of 6.0×10-3mg/L in 150 hours; the higher temperature, the rapider rate of degrading the same quantity of formaldehyde, as witch it cost 50 hours for 5 gram of sample oxidating formaldehyde with raw concentration of 2.0×10-3mg/L completely under 15℃, but cost 12 hours under 45℃; the stronger light intensity, the rapider rate of degrading the formaldehyde, as witch it cost 14 hours for 5 gram of sample oxidating formaldehyde with raw concentration of 2.0×10-3mg/L completely under the light intensity of 8100Lm/m2, but it nearly could not degrade the formaldehyde under 0 Lm/m2; the more relative humidity, the faster our sample degrading the formaldehyde, as witch 5 gram of our sample oxidated formaldehyde with raw concentration of 2.0×10-3mg/L to 3.72×10-5mg/L in 14 hours under the relative humidity of 50%, but to 1.0×10-5mg/L under the relative humidity of 80%.更多还原