Preparation Of Silicon-based Particle Modified Polyurethane Membrane And Its Performances For Separation Of Phenol From Water

The application of pervaporation technology in the recovery of phenol in water has both economic value and environmental significance.The membrane material directly determines the separation efficiency and becomes the key to this technology.Polyurethane（PU）has excellent mechanical and film-forming properties and good selectivity to phenol.Thus,it has great potential for industrial application,while its comprehensive separation performance needs further improvement.The addition of inorganic particles to the organic film matrix to prepare the mixed matrix membranes is expected to obtain a de-phenolic membrane with better comprehensive separation performance.It is very important to select a suitable modified matrix and modifier.In this paper,the preparation,characterization and separation performance of the mixed matrix membranes were investigated from both the PU membrane matrix and the inorganic modifier.First,the PU matrix membrane was screened and optimized;then,the mesoporous Si O₂particles and Si O₂-ZIF-8 composite particles with different hollow structures were prepared by St?ber method and water etching process,and the structure was characterized.Finally,the PU mixed matrix film was prepared by using the above inorganic particles as filler.The properties of the membrane and the properties of pervaporation for dephenolization were investigated by means of FTIR,thermogravimetry and contact angle.The results show as the following:1)In the screening of PU matrix membrane,from the point of the external morphology and preparation process,the commercial PU membrane’s preparation process is more simple and easy,and it has better film-forming property and toughness than HTPB-PU.From the perspective of pervaporation separation performance,The commercial product PU has better affinity with phenol and exhibits more stable and superior separation performance than HTPB-PU membrane;2)St?ber method combined with water etching process can successfully produce monodisperse mesoporous hollow silicon spheres with a particle size of about 500 nm.It can be found by electron microscopy and nitrogen adsorption desorption to have a hollow structure with a specific surface area of about 681.7 m²/g,mesoporous size is about 2-4 nm.The Si O₂-ZIF-8 composite particles involving ZIF-8 inside have a morphology similar to pure silica particles;3)The five kinds of Si O₂and silicon-based composite particles prepared thus obtained can simultaneously improve the permeability and selectivity of the PU membrane within a certain loading.It overcomes the Trade-off phenomenon between the separation factor and the permeate flux,and achieves a good modification effect.In comparison,the surface of the hollow Si O₂particles has more polar groups,so it can inhibite swelling and make the modified membrane permeability lower than that of the solid Si O₂modified membrane,while the selectivity is higher than the latter.The hollow Si O₂particles obtained by etching at 90℃have a larger cavity structure than the ones at 70℃,and the modified membrane also has higher permeability and lower selectivity than the latter.However,for the Si O₂-ZIF-8 composite particles obtained by etching at 90℃,the permeability and selectivity of the modified membrane are higher than that of the ones at70℃.Its permeation flux is 30.15 kg·μm·m^-2·h^-1at a loading of 2 wt%,and the separation factor is 30.24,which is 20.60%and 27.59%higher than those of pure PU membrane.