Research On The Preparation And Application Of Polyphenylene Sulfide Porous Membrane

With the constant widening applications of membrane separation technology,membrane separation technology beome a simple,efficient,energy-saving separation technique and it has been widely used in many fields.However,conventional membrane materials are easily damaged under harsh environments such as strong acids,strong alkalis and organic solvents.Thus,it is highly desirable to develop a material with excellent chemical resistance.Polyphenylene sulfide(PPS)is a thermoplastic polymer with excellent thermal stability and superior strong acid and alkali resistance performance.Therefore,PPS is expected to become a promising material to deal with high temperature corrosive solutions and organic solvent waste liquids.In this paper,PPS membranes were prepared via thermal phase separation(TIPS)technology.In addition,the structure and properties of prepared membranes were studied.All the prepared samples were applied to ultrafiltration,membrane distillation and oil-water separation.The specific research contents are summarized as follows:PPS microporous membranes were prepared via TIPS by using caprolactam(CPL)as the diluent,and hydrophilic micro-scale silica(SiO2)as the additive.The effects of different polymer concentrations and different additive concentrations on the structure and properties of membrane were investigated.The pore size,porosity,water contact angle,permeate flux and bovine serum albumin rejection were measured to analyze the ultrafiltration separation performance of PPS microporous membranes.With the addition of hydrophilic SiO2 particles,the ultrafiltration separation performance and antifouling ability of PPS microporous membranes improved obviously.PPS hydrophobic microporous membranes were fabricated via TIPS with diphenyl ketone(DPK)and benzoin(BZ)as mixed diluent.The effects of different mass ratio of DPKIBZ on the structure and properties of membranes were investigated.As DPK content increased,the interaction between PPS and diluents became stronger and the membrane micro-structures changed from honeycomb,bi-continuous to spherical particle structure via liquid-liquid(L-L)phase separation process.Especially,the membrane with the bi-continuous network structure and Berberis thunbergii var.atropurpurea Chenault leaf-like structure prepared from the mixed diluent of 15 wt.%DPK and 85 wt.%BZ,and achieved the maximum permeate flux of 22.8 L/(m2·h)and the highest salt rejection of 99.99%in vacuum membrane distillation(VMD).Most importantly,PPS hydrophobic microporous membranes possessed the superior chemical resistance and exhibited the excellent stability in corrosive water desalination.The superhydrophobic PPS membrane was prepared by loading hydrophobic Si02 nanoparticles in the casting solution,and PPS-SiO2 hybrid porous membranes were fabricated by TIPS which were applied to oil-water separation under harsh environments.The effects of different SiO2 contents on the structure and properties of hybrid membranes were investigated.The introduction of hydrophobic SiO2 particles promoted the soild-liquid separation,resulting in the structure of membrane bottom surface changing from branch porous structure to spherical micro-nano hierarchical structure.When the concentration of SiO2 was 4 wt.%,the surface structure of PPS hybrid membrane was lotus leaf-like hierarchical micro-nano structure with water contact angle(WCA)of 156.9°and oil contact angle(OCA)of 0°.This new membrane could be used to selectively separate a series of different water-in-oil emulsions with 99.9%separation efficiency.Moreover,the superhydrophobic PPS hybrid membrane exhibited the excellent self-cleaning antifouling performance,cycling stability and superior resistance to strong acid and alkali.Janus PPS membranes with opposing surface wettability were conveniently fabricated by single-surface deposition of polydopamine/polyethylenimine(PDA/PEI).The effects of different modification time on the structure and properties of Janus membranes were investigated.As the modification time increase,the hydrophilic properties of the modified membrane surface were improved.When the modification time was 4h,the modified surface of the Janus membrane exhibited superhydrophilicity and underwater superoleophobicity with WCA of 0°and underwater OCA of 156°.The modified surface could be used to effectively separate oil-in-water emulsions with 99.4%separation efficiency.The unmodified surface exhibited superlipophilicity and underoil superhydrophobicity with OCA of 0° and underoil WCA of 151°.The unmodified surface could be used to effectively separate water-in-oil emulsions with 99.7%separation efficiency.In addition,the Janus membrane with opposite wettability has stable recyclability,excellent antifouling property and superior acid-base resistance property.