负载纳米TiO_(2)功能集料的制备及其光催化性能

Preparation of TiO_(2)-loaded Functional Aggregates and Their Photocatalytic Performance

目的采用负载法制备纳米TiO_(2)功能集料,提高集料的光催化性能和TiO_(2)的有效利用率。方法以石英砂为载体、纳米TiO_(2)(NT)悬浮液为负载媒介,制备表面负载NT的功能集料,通过SEM、EDS、XRD、XRF与FT-IR等测试方法对其进行表征分析,研究了NT悬浮液浓度、负载时间与循环负载次数对负载NT功能集料光催化性能及稳定性的影响规律。结果以0.5%SDS表面活性剂溶液配制成浓度(质量分数)1%的NT悬浮液稳定性最佳,经2 mol/L NaOH预处理24 h的石英砂碱改性效果最好,将石英砂置于NT悬浮液中浸泡30min、烘干,循环负载5次,得到的负载NT功能集料,其表面TiO_(2)质量分数约为0.34%,对NO降解率可达98%。负载NT功能集料经淡水、饱和Ca(OH)2溶液浸泡7 d后,集料表面所含Ti含量损失率分别为11.3%、9.5%,其对NO降解率略有下降,仍高达88%、91%;且在冲刷作用下,其表面Ti含量损失率仅为21.9%,其光催化性能仍可达到70%。结论负载NT功能集料的光催化性能随NaOH溶液浓度、预处理时间、NT悬浮液浓度以及循环负载次数的增加而增大,其中,循环负载次数对集料光催化性能的影响最大。采用碱液对集料进行表面预处理,促进了集料表面与NT之间生成Ti—O—Si化学键,提高了功能集料的光催化性能和耐久性。

The work aims to apply a loading method for the preparation of functional nano-TiO_(2)(NT)aggregates on a carrier substrate,so as to increase the effective surface area of NT by capitalizing on its distinctive light absorption characteristics,enhance the photocatalytic performance of the aggregates,and optimize the utilization efficiency of NT.The integration of these functional aggregates into building materials has the potential to enhance their overall functionality and environmental sustainability.Quartz sand was selected as the support material and NT suspension was prepared by combining a surfactant solution with the NT powder.The loading of NT onto the surface of quartz sand was achieved through immersion,resulting in the formation of functional aggregates with loaded NT.A range of analytical techniques including scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),X-ray fluorescence spectrometry(XRF)and Fourier transform infrared spectroscopy(FT-IR),were employed to characterize the materials.These analyses were conducted with the objective of evaluating the dispersion stability of the NT suspension,the microstructure of the NT functional aggregates and the loading amount of NT.The photocatalytic performance and stability of the loaded NT functional aggregates were evaluated by measuring the degradation rate of NO gas with a gas analyzer.The effects of NT suspension concentration,loading time and cyclic loading on the photocatalytic performance and stability of the functional aggregates were investigated.The results demonstrated that the stability of the NT suspension was optimized when it was prepared with a 0.5%SDS surfactant solution at a concentration of 1%.The quartz sand,which had been pre-treated with a 2 mol/L NaOH solution for 24 hours,exhibited the most effective alkali modification,thereby facilitating the subsequent loading process.The immersion of silica sand in the NT suspension for 30 minutes,followed by drying and cyclic loading for five times,resulted in the formation of functional aggregates with a surface NT content of approximately 0.34%.Notably,these aggregates exhibited an exceptional NO degradation rate of 98%when subject to NO gas testing.Further experiments were conducted to assess the stability of the loaded NT functional aggregates.These were immersed in freshwater and saturated Ca(OH)2 solution for 7 days.The results demonstrated that the loss rates of surface Ti content were 11.3%and 9.5%,respectively,with a slight reduction in NO degradation rates of 88%and 91%.Notwithstanding the increase in the loss rate of surface Ti content to 21.9%under rinsing conditions,the photocatalytic performance remained at 70%.In conclusion,the photocatalytic performance of the loaded NT functional aggregates demonstrates a positive correlation with increasing NaOH solution concentration,pretreatment time,NT suspension concentration,and cyclic loading times.Cyclic loading is identified as the factor with the greatest effect on the photocatalytic performance of the aggregates.Moreover,the alkali pre-treatment process facilitates the formation of Ti-O-Si chemical bonds,thereby enhancing the photocatalytic performance and durability of the functional aggregates.The successful integration of these loaded NT functional aggregates into building materials promises to enhance their environmental sustainability and functionality in various applications.