Preparing High Performance Separation Membrane Material Through Electrospinning Technology

Recently,as the growth of industrial civilization of the human beings,the water contamination problems have attracted lots of attentions.It is urgent to develop a novel technology to overcome the withdraw brought by the pollution.Membrane separation technology is considered as an ideal solution to solve the difficulties because of its better flux,higher separation efficiency,energy saving and easy to deploy compared with traditional separation methods.In the membrane producing fields,electrospinning technology owning specific advantages due to its potential to produce massive nano fiber membranes.However,pure nano-fiber membrane's separation performance is still limited.In order to enhance the performance of the membrane,modified with the Metal Organic Framework(MOFs)is studied because of its pore size and high compatibility.This article focusses on creating high performance membrane in separation through electrospinning and reveal the transport mechanism by computer simulation.Firstly,the ultra-sonic pealing 2D-MOF nanosheets were added into the PA layers which made by interfacial polymerization reaction.Compared with the traditional MOFs materials,the 2D-MOFs nanosheets is easily distributed in the water phase and could accelerate the water molecules'transportation due to its hydrophilic functional groups.The results of the experiments showed that the modified membrane had increased almost 1.5 times higher in the flux than the unmodified membrane since the addition of the 2D-MOF nanosheets.Also,the rejection of the Na Cl still remained99%.Then we utilized electrospinning device to create high performance oil-water separation membrane through Contra-diffusion method which based on the PAN fibers'characters.We combined the modified hydrophilic ZIF-8 crystals(which achieved by connecting PGA)and the hydrophobic ZIF-L crystals into one membrane.These different wetting properties has promised the ability to separate the oil-water mixtures.These nanostructured fiber surface feature Janus wetting properties which allowing for gravity-driven,highly efficient oil-water separation which corresponding flux reached4769L/m^-2·h^-1to mixtures and 1430 L/m^-2·h^-1to emulsions.The recovery of the flux had reached 75%of the original since the deionized water cleaning process after 20times cycle tests which given the evidence of the industrial application.At last,the computer simulation has been operated to use Molecular Dynamic and Density Functional Theory which explain the mechanism of the above experiments.At the first stage,the diffusion coefficient of the water molecules in the membrane's PA layer which after the adding 2D-MOF nanosheets is higher than the pure TFC membrane because of the free space for transportation had been enlarged.This explained the results of the flux increasing phenomena during the experiments.At the second stage,the change of the electrostatic energy contribution was calculated by the DFT which explained the wetting properties of the modified ZIF-8 crystals.Ability of connecting H bond is one of the key factors that influenced the separation of water and oil.Compared with the results of the membrane tests,the simulation results has promised a deep research for the future study of the membrane.