<p>Pervaporation (PV) desalination, a promising technology to produce clean water, lacks some fundamental understanding of the molecular transport mechanism. We perform molecular dynamic simulations to unravel the molecular transport mechanism in polyvinyl alcohol PV desalination membranes. It is revealed that the dispersion forms of confined water molecules transform from nano-sized clusters to single molecules as the concentration gradient decreases within the membrane. The diffusion modes of confined water molecules with various dispersion forms are distinguished. The solvation free energy analysis explains the compensation mechanism of ions in membranes. Based on the simulation results, an analytical expression is derived to describe the relationship between the transport diffusion coefficient and solubility of confined water molecules. Using this analytical expression, a solution-diffusion model is established to calculate the permeability of PV desalination, and is validated with experimental results. These findings pave an avenue for building a theoretical framework of PV desalination.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

A fundamental mass transport model based on molecular insights for pervaporation desalination

  • Shen-Hui Li,
  • Heng Mao,
  • Ying-Nan Feng,
  • Li-Hao Xu,
  • Hao Qi,
  • Zhi-Ping Zhao

摘要

Pervaporation (PV) desalination, a promising technology to produce clean water, lacks some fundamental understanding of the molecular transport mechanism. We perform molecular dynamic simulations to unravel the molecular transport mechanism in polyvinyl alcohol PV desalination membranes. It is revealed that the dispersion forms of confined water molecules transform from nano-sized clusters to single molecules as the concentration gradient decreases within the membrane. The diffusion modes of confined water molecules with various dispersion forms are distinguished. The solvation free energy analysis explains the compensation mechanism of ions in membranes. Based on the simulation results, an analytical expression is derived to describe the relationship between the transport diffusion coefficient and solubility of confined water molecules. Using this analytical expression, a solution-diffusion model is established to calculate the permeability of PV desalination, and is validated with experimental results. These findings pave an avenue for building a theoretical framework of PV desalination.