【作者】 舒畅；

【导师】 王发洲；

【作者基本信息】 武汉理工大学 ， 材料科学与工程， 2017， 硕士

【摘要】 室内空气净化已成为目前光催化技术应用的重要领域,水泥基材料凭借使用量高、暴露面大和成本低廉等特点,使研制水泥基光催化材料以解决室内空气净化问题具有较大优势。处理好光催化剂与载体的有效复合,利用室内弱光环境条件进行高效光催化降解,是开发室内光催化空气净化技术的研究难点。本文以碱式氯化镁晶须（BMCW）作为水泥基体,SiO₂为基体改性剂,TiO₂为光催化剂,制备了镁相水泥基光催化材料（MCBPM）。将MCBPM与市售水泥基腻子粉进行复合,通过Ag源改性,制备了光催化/可见光催化功能性墙面涂料（PFWC/VPFWC）。主要研究内容及成果如下:在分析了BMCW原材料组成与晶体生长及物理性能相互影响规律的基础上,确定了TiO₂负载基体的最优合成方法。研究掺入不同浓度正硅酸四乙酯（TEOs）对BMCW表面进行SiO₂合成改性的影响,发现在BMCW表面合成的SiO₂排列方向与BMCW在生长方向上一致,说明改性碱式氯化镁基体（BMCW/SiO₂）具有较强的物理稳定性。TEOs引入浓度过大,会使SiO₂粒径过大;反之,SiO₂对BMCW的表面覆盖则不够完全。当SiO₂与（BMCW+SiO₂）质量比为40%时,制备的BMCW/SiO₂-40%是TiO₂负载的最佳基体。在合成BMCW/SiO₂-40%基体的基础上,采用TiO₂水溶胶负载法和原位合成负载法制备MCBPM。发现在水溶胶负载法制备过程中,TiO₂和SiO₂因等电点对应pH值不同,负载搅拌混合液pH=6.20⁶.55时最有利于TiO₂的负载。在此pH范围内,逐渐增大TiO₂的负载浓度,会相应增大TiO₂的表面堆积程度,形成含有4⁹nm小孔的表面结构。TiO₂的负载浓度为5%时制备的MCBPM-5%,对气相甲苯的紫外光三小时催化降解率为55%。在原位合成负载法制备MCBPM过程中,煅烧过程会使MCBPM失去结晶水而变得不稳定。当TiO₂的负载浓度为5%时,MCBPM-5的降解率最高达27%,之后随着TiO₂负载浓度的继续增大,TiO₂结晶颗粒会迅速增大,反而导致光催化活性的降低。系统分析结果表明,采用水溶胶负载型MCBPM制备VPFWC的技术路线会是最优选择。为提高单位TiO₂的利用率,选用MCBPM-5%作为制备PFWC/VPFWC的添加剂,经实验证明,MCBPM-5%具有极好的催化稳定性。逐渐增大MCBPM-5%的引入量,PFWC的光催化活性亦随之增大,选择引入量为439g/m²制备的PFWC-439作为Ag沉积改性材料。经过自组装-光诱导过程,Ag/AgCl被均匀沉积到了PFWC-439表面。随着Ag沉积量的增大,Ag/AgCl颗粒逐渐增大、分布更密集、在紫外光和可见光区域的吸收强度更大。但是,Ag源引入量过大时,会带入过多的无水乙醇水溶液使腻子粉“二次水化”,将MCBPM-5%包裹在水化产物之中,从而降低了光催化活性。选择Ag沉积量为16.62g/m²时制备的VPFWC-16.62对气相甲苯的可见光和紫外光三小时催化降解率均为最高,分别是28%和73%,且具备极好的光催化稳定性。更多还原

【Abstract】 Indoor air purification has become an important field of the current application of photocatalysis technology,developing cement based photocatalytic materials to solve the problem of indoor air purification possess great advantage because of cement based materials’characteristics of high usage,large exposed surface and low cost.Assuring the stability of cooperation between photocatalyst and carrier,and maintaining the efficient photocatalytic performance under the indoor environment of low light are essential research focuses.In this paper,Magnesium Cement Based Photocatalytic Materials（MCBPM）were prepared by cement matrix（Basic Magnesium Chloride Whisker,BMCW）,matrix modifier（SiO₂）and photocatalyst（TiO₂）,Photocatalytic Functional Wall Coatings（PFWC）were prepared by combining MCBPM with cement based putty powder.And after Ag modification,Visible Photocatalytic Functional Wall Coatings（VPFWC）were also prepared.The main research contents and results are as follows:Based on the analysis of the relationship among the raw materials composition,the crystal growth and the physical properties of BMCW,the optimal synthesis method of TiO₂ load matrix was determined.Through studying on the synthesis of SiO₂ doped modification effect on BMCW surface by different concentration of TEOs,we found that the orientation of SiO₂ synthesized on the surface of BMCW is consistent with that of BMCW in the growth direction,which means that modified basic magnesium chloride matrix（BMCW/SiO₂）exhibits good physical stability.Over high TEOs concentration results in over large particle size of SiO₂.On the contrary,the surface coverage of SiO₂ on BMCW is not enough.Therefore,when the mass ratio of SiO₂ and（BMCW+SiO₂）is 40%,the prepared BMCW/SiO₂-40%is the best TiO₂ load substrate.On the basis of the synthesis of BMCW/SiO₂-40%matrix,the MCBPM were prepared by the TiO₂ hydrosol loading and in-situ synthesis loading methods.During the preparation of hydrosol load process,because of the different corresponding pH of the isoelectric point of TiO₂ and SiO₂,mixing liquid’s pH=6.20⁶.55 is the most suitable pH for the TiO₂ load.Within this pH range,increasing the concentration of TiO₂ graduallywill increase the degree of surface accumulation of TiO₂,thus forming a surface structure containing 4⁹ nm holes.MCBPM-5%were prepared at the 5%TiO₂ loading concentration,and the photocatalytic degradation rate of gas phase toluene was 55%under UV after 3 hours.In the in-situ synthesis loading process,the calcination process make MCBPM lose crystal water and become unstable.When the loading concentration of TiO₂ is 5%,the degradation rate of MCBPM-5 is up to 27%,and with the increase of TiO₂ loading concentration,TiO₂crystal particles increase rapidly,which leads to the reduced photocatalytic activity.The results of systematic analysis show that the technical route of VPFWC prepared by hydrosol-loaded MCBPM is the best choice.To increase the utilization of TiO₂,MCBPM-5%with excellent photocatalytic stability was used as the additive to prepare PFWC/VPFWC.With the increase of the MCBPM-5%introduction,photocatalytic activity of PFWC is also increased,PFWC-439 prepared with an introduction amount of 439g/m² was selected as Ag deposition modified material.Ag/AgCl was uniformly loaded onto the surface of PFWC-439 after self-assembly-light induction.With the increase of the Ag amount,the Ag/AgCl particles increase gradually,the distribution is denser,and the absorption intensity is stronger in the ultraviolet and visible regions.However,when excessive Ag sourceis introduced,too much anhydrous ethanol solution is introduced,which makes the putty powder"secondary hydration",and MCBPM-5%will be encapsulated in the hydration product and lead to reduce the photocatalytic activity.Therefore,VPFWC-16.62（prepared with the Ag deposition amount of16.62g/m²）delivers the highest photocatalytic degradation rate of toluene under visible and ultraviolet after 3 hours（28%and 73%,respectively）,and also exhibits excellent photocatalytic stability.更多还原