Size Effect of Silica Shell on Gas Uptake Kinetics in Dry Water

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• 作者：Yong Li ; Diwei Zhang ; Dongsheng Bai ; Shujing Li ; Xinrui Wang ; Wei Zhou
• 刊名：Langmuir
• 出版年：2016
• 出版时间：July 26, 2016
• 年：2016
• 卷：32
• 期：29
• 页码：7365-7371
• 全文大小：447K
• 年卷期：0
• ISSN：1520-5827

文摘

Two kinds of dry water (DW) particles are prepared by mixing water and hydrophobic silica particles with nanometer or micrometer dimensions, and the two DW particles are found to have similar size distributions regardless of the size of the silica shell. The CO₂ uptake kinetics of DW with nanometer (nanoshell) and micrometer shells (microshell) are measured, and both uptake rate and capacity show the obvious size effect of the silica shell. The DW with a microshell possesses a larger uptake capacity, whereas the DW with a nanoshell has a faster uptake rate. By comparing the uptake kinetics of soluble NH₃ and CO₂ further, we found that the microshell enhances the stability and the dispersion degree of DW and the nanoshell offers a shorter path for the transit of guest gas into the water core. Furthermore, molecular dynamics simulation is introduced to illustrate the nanosize effect of the silica shell on the initial step of the gas uptake. It is found that the concentration of gas molecules close to the silica shell is higher than that in the bulk water core. With the increase in the size of the silica shell, the amount of CO₂ in the silica shell decreases, and it is easier for the gas uptake to reach steady state.