Study On Desalting Mechanism Of Special-shaped Low-dimensional Carbon-based Nanostructures

Clean fresh water is the basic requirement for human life to survive,and it is the most important factor for social development and progress and the continuation of civilization.Scientific research and practice have proved that desalination can achieve effective and sustainable freshwater acquisition,and is one of the most important solutions to alleviate the global shortage of freshwater resources.In recent years,lowdimensional nanomaterials have the advantages of high efficiency and low energy consumption in the field of seawater desalination,which have attracted widespread attention and have flourished in scientific and technological research.Lowdimensional nanomaterials such as graphene and carbon nanotubes have excellent chemical properties and ultrafast transport properties,and have become the most representative new low-dimensional nanomaterials that can be used in seawater desalination.The study of the transport process of water molecules and ions in lowdimensional nanomaterials is helpful to further explore basic scientific problems such as special processes and mass transfer mechanism under nano-restricted scale,and can provide reference value and guidance for the design and optimization of structural parameters of low-dimensional nanomaterials and applications in seawater desalination and other fields.This paper focuses on the key issues of water transport and desalination in lowdimensional nanomaterials such as graphene and carbon nanotubes,and focuses on the transport of water molecules and desalination effects in low-dimensional nanochannels due to their different structures,surface wetting properties,external pressure.Combined with the positive effect of the slip flow of water molecules in low-dimensional nanomaterials on the water flux,a graphene conical channel as a reverse osmosis membrane model was proposed and constructed,revealing its excellent desalination effect and high water flux.The relationship between the flow resistance and the structural parameters of the tapered channel is clarified.Under the constant external conditions,the cone angle and channel size play a key role in the desalination process and have optimal values.The influence of hydrophilicity and hydrophobicity on the transport of water molecules was studied by adjusting the wettability property of the tapered channel.The outflow model of carbon nanotubes arranged in parallel in a single layer is further proposed,revealing its high water flux characteristics under high desalination rate,and the slip flow of water molecules around the outer wall of carbon nanotubes is studied.The configurational distribution of a large number of water molecules reveals the configurational changes of water molecules during the flow process and the impact on water flux.There is a large amount of low-grade thermal energy in the actual industrial production and living environment.In this paper,the special-shaped low-dimensional nanomaterial fluid system is combined with the external environment temperature difference and light as the driving force to desalinate the salt solution.Controllable net directional fluid transport is achieved by adjusting the hydrophilicity and hydrophobicity of the material surface.The key role of wettability between the interface of nanomaterial and the fluid in thermal permeation transport is revealed.The effect of channel length on water flux was studied,and the optimal value of the effect of channel length on water flux was calculated.In the case of coupling the environmental factors of temperature difference and external pressure,the water fluxes of the tapered channel and the straight through hole were compared,and the influence of the channel structure on the desalination effect was revealed.In particular,a positive synergistic effect was found that the water flux under the combined effect of temperature difference and external pressure was higher than the sum of the water fluxes under the single coupling condition.Using the properties of graphene oxide to generate asymmetric net charge distribution on the surface under external asymmetric light,a graphene oxide nano-desalination model was constructed,the transport process of ions in the channel was studied,and the high-speed reverse motion of anions and cations was observed,revealing the efficient desalination performance of this model.The microscopic transport process and mechanism of water molecules and ions in low-dimensional nanomaterials are of great scientific significance in the fields of seawater desalination,ion screening,and wastewater treatment.Therefore,studying the special transport mechanism in confined spaces in low-dimensional nanomaterials,with the help of theoretical calculations,scientific analysis,predictions and interpretations of the model,is expected to provide new insights and strategies for the development and design of seawater desalination systems,by this way,optimizing the performance parameters and structure of the system has important academic value for further improving the transmembrane flux,saving energy,reducing energy consumption,improving the operation efficiency and the desalination effect.