Molecular dynamics simulation of seawater pervaporation process with CHC-hydrophilic gel composite photothermal membrane

Pervaporation technology recently plays an important role in seawater desalination and water purification. Carbon honeycomb (CHC) is a novel carbon allotrope, which combines the advantages of graphene and carbon nanotubes. It exhibits excellent photothermal absorption characteristics and a porous structure, making it highly promising for seawater desalination. However, current research on CHC desalination technology mainly focuses on reverse osmosis desalination, with most studies limited to the mechanisms of single CHC membrane materials. On the other way, the application of coupling CHC materials with other functional nanomaterials in seawater photothermal membrane pervaporation remains unexplored. The relevant microscale water molecules and salt ion transport mechanisms also need further clarification. This work uses molecular dynamics analysis and establishes a CHC-hydrophilic gel composite pervaporation membrane structure for seawater desalination, utilizing hydrogen bonding of the hydrophilic gel to enhance CHC water transport. Meanwhile, this work examines the influence of temperature on the water molecule and salt ion transport properties of the composite membrane. Additionally, this work also compares the pervaporation water flux of composite membranes and single membrane under different temperature conditions. The results indicate that increasing temperature boosts the in-teraction strength between hydrophilic gel and the water molecules within CHC pores, thereby intensifying the water molecule transport process. However, excessively high temperatures can lead to the formation of larger hydrated ion clusters, limiting water molecule transport. In this work, under moderate-temperature conditions, hydrophilic gel significantly enhances the water flux in pervaporation (about 128%). Moreover, ion clusters do not block membrane pores, demonstrating good desalination performance and self-cleaning properties. These findings provide insights into designing new efficient photothermal pervaporation devices.