| Due to the rapid growth of population,the rapid development of industry and the failure to discharge industrial wastewater up to standard,the shortage of fresh water resources and water pollution problems have become increasingly prominent.A lthough seawater accounts for the majority of the earth’s water resources(about 97%),people cannot directly use seawater in many actual productions,because seawater contains a large number of harmful substances,such as salt ions,heavy metal ions and impurities.Therefore,filtering or separating these harmful substances through desalination technology to obtain a large number of fresh water resources has become one of the hot issues in current scientific research.The development of nanomaterials based on reverse osmosis(R 0)technology provides new possibilities for desalination technology.In this study,we proposed and designed an excellent reverse osmosis membrane composed of fluorographene(fluorinated graphene,FGRA)nanochannels using molecular dynamics simulation methods.To explore its performance in seawater desalination and heavy metal wastewater purification systems,respectively.T he specific results are as follows:In the first work,we explored the effectiveness of F-GRA reverse osmosis membranes in desalination systems.T he membrane was found to have extremely high water permeability(up to 61.1 L/cm2/day/MPa)and almost complete ion suppression.C ompared with previous theoretical studies,F-GRA nanochannel membranes exhibit more promising desalination properties than many other nanomaterials.T his excellent desalination performance of the FG R A channel is attributed to the negatively charged and hydrophobic surface of F-G R A,where electrostatic interactions(attraction or repulsion)between ions and the F-G R A surface result in ideal ion repulsion,while the ultra-low water friction mediated by the hydrophobicity of the F-G R A membrane makes it have excellent water permeability.The calculation of the average force potential energy further revealed that water molecules have the lowest free energy barrier relative to ions when passing through the F-G R A channel,indicating that water molecules are more conducive to smoothly passing through the F-GRA channel than ions.In the second work,we investigated the application of F-G R A filtration membranes in the purification of heavy metal wastewater.It was found to achieve both high water permeability(up to 61.1 L/cm2/day/M Pa)and near-perfect heavy metal ion retention.P ositively charged heavy metal ions interact strongly with fluorine atoms on the surface of FG R A,thereby blocking the passage of ions through nanochannels.N ext,we calculated the free energy of ions and water molecules when passing through the channel,and the energy barrier of water molecules is lower than that of the other three heavy metal ions,indicating that water molecules can pass through the F-G R A channel faster.W e analyzed the number of ions in the channel and found that a large number of heavy metal ions were adsorbed on the surface of FG R A,restricting their passage within the channel.T hese studies provide a theoretical basis for the future design of F-G R A-related permeable membranes,and are expected to make them promising nanomaterials in future reverse osmosis membrane applications. |
