Size characteristics and aging of airborne SiO2 nanoparticles
作者单位：National Center for Nanoscience and Technology
会议名称：《第十二届全国气溶胶会议暨第十三届海峡两岸气溶胶技术研讨会》
会议日期：2015年
学科分类：1004[医学-公共卫生与预防医学(可授医学、理学学位)] 07[理学] 070205[理学-凝聚态物理] 08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 100402[医学-劳动卫生与环境卫生学] 10[医学] 0702[理学-物理学]
基 金：funding of this project by Chinese Academy of Sciences(XDA09040400)
关 键 词：temporal evolution surface deposition coagulation particle size distribution
摘 要：Exposure to airborne nanoparticles in the occupational setting has been considered as a potential hazard, and has drawn much attention in research. The temporal evolution of airborne nanoparticles and the associated mechanisms need to be understood in order to design better control and protection. In this study, size characteristics and aging of airborne SiO 2 nanoparticles are investigated in a 1.2 m3 chamber under still conditions. The effects of coagulation and surface deposition are quantitatively assessed by measuring particle loss rates and calculating deposition velocity and coagulation coefficient parameters. To simulate workplace environment, the initial SiO 2 nanoparticle concentrations cover the range from 2.16 × 103 cm-3 to 1.79 × 105 cm-3. The results show that the overall loss rates are from 6.97 × 10-5 s-1 to 8.07 ×10-4 s-1. It was revealed that particle loss rates due to coagulation dominate with the fraction over 58%. Finally, it is interesting to find that the evolution of particle size with time is following d /3tefor lognormal-distribution nanoparticles. These findings suggest that the coagulation mechanism may be of more significance in terms of nanoparticles even with lower concentrations in certain workplace environment.