Department of Chemistry, School of Science, Beijing Technology and Business University , Beijing 100048, China.
Langmuir. 2016 Jul 26;32(29):7365-71. doi: 10.1021/acs.langmuir.6b01918. Epub 2016 Jul 12.
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.
两种干水（DW）颗粒通过混合水和具有纳米或微米尺寸的疏水性二氧化硅颗粒来制备，并且发现这两种 DW 颗粒无论二氧化硅壳的尺寸如何都具有相似的尺寸分布。测量了具有纳米壳（纳米壳）和微米壳（微壳）的 DW 的 CO2 吸收动力学，吸收速率和容量都表现出二氧化硅壳的明显尺寸效应。具有微壳的 DW 具有更大的吸收容量，而具有纳米壳的 DW 具有更快的吸收速率。通过进一步比较可溶性 NH3 和 CO2 的吸收动力学，我们发现微壳增强了 DW 的稳定性和分散度，而纳米壳为客体气体进入水核提供了更短的通道。此外，引入分子动力学模拟来阐明二氧化硅壳对气体吸收初始步骤的纳米尺寸效应。结果发现，靠近二氧化硅壳的气体分子的浓度高于本体水核中的浓度。随着二氧化硅壳尺寸的增加，二氧化硅壳中 CO2 的量减少，并且更容易达到气体吸收的稳态。
