InterPore2025

Capillary condensation mechanism of water in silica nanopores

21 May 2025, 11:50

15m

Oral Presentation (MS13) Fluids in Nanoporous Media MS13

Speaker

Mr Zhenyao Xu (State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & College of Energy, Chengdu University of Technology)

Description

The phenomenon of capillary condensation of water in porous media is common in nature. It can significantly alter the properties of adsorption, wetting and flow in porous media. It is of great importance in the fields of materials, environment and energy. However, at the nanoscale, the internal mechanism of capillary condensation in porous media has not been clearly explained. In this study, the capillary condensation of water in silica nanopores was investigated by molecular simulation. The effects of temperature, pore size and surface chemical properties on the capillary condensation of water were investigated. The microscopic mechanism of water in the process of capillary condensation was revealed from the perspective of molecular thermodynamics and dynamics. The results show that with increasing temperature, the saturated vapor pressure of water molecules increases, which is not conducive to capillary condensation. The smaller the nanopore size, the lower the saturated vapor pressure when capillary condensation occurs, and the easier the capillary condensation occurs. The van der Waals interaction between water molecules and different pore walls is different, leading to the difference in effective pore radius, which affects the condensation process of water molecules in different surface pores. In addition, the hydrogen bonds between water molecules play an important role in the formation of the condensed phase. The water molecules are connected to each other by hydrogen bonds and gradually condense into larger droplets. The hydrogen bonds within the condensed phase form a three-dimensional network structure that holds the water molecules tightly together. This structure can resist small external perturbations and maintain the relative stability of the condensed phase. This study provides an important insight into the aggregation behavior of water in porous media.