| With the development of science and technology, membrane separation method has foundmore and more application. Among them, ultrafiltration and composite membranes with denseseparation layers play an important role in wastewater treatment, backer water desalination,seawater desalination and pure water production etc. Development of thermal stable membranes ismeaningful since it can further broaden membrane application fields, improve separation efficiencyand spare energy. As novel polymers developed by our lab, poly (phthalazinone ether sulfoneketone)s (PPESK) are ideal thermal stable membrane materials for advantages such as thermalstable, chemical stable and solubility in some solvents etc.Blended ultrafiltration membranes were prepared by blending sulfonated poly-(phthalazinoneether sulfone ether ketone)s(SPPESK) with PPESK, to be used as support membrane of thermalstable composite membranes. Influence of polymer concentration, evaporation time and SPPESKcontent on membrane structure and separation properties was studied systematically. Resultsindicate that with the increase of total polymer content in casting solution, diameter of membranestructure pore reduced, rejection of PEG20000 increased, water permeability declined. Compare topure PPESK support membrane, the blend support membranes show higher PEG6000 rejectionand high water flux. With the SPPESK content in the casting solution increased from 0 to 7wt.％,thickness of the dense separation layer of the support membrane reduced, diameter of membranestructure pore reduced, pure water contact angle of support membrane declined. With 3wt.％SPPESK content, the blend membranes rejected clayton yellow and PEG20000 by 99％, purewater flux was 491 L·m-2·h-1. The blend membranes showed good thermal stability, rejectedanionic sulphur dye by 99％at 95℃, 0.2MPa operation pressure, and water flux was 751 L·m-2·h-1.Desalted the dye solution with 5 recycles.Seven types of series composite membranes that have different function layers were preparedby interfacial polymerizing isophthaloyl chloride(IPC), 1,3,5-benzenetricarbonyl chloride(TMC),and 1,2,4,5-benzeneteracarbonyl tetrachloride(BTTC) with 1,3-benzenediamine(MPDA), 1,2-dimethylenediamine(DMDA) and piperazine (PIP) respectively on the surfaces of PPESK supportmembranes. The chemical components and morphology of the composite membranes with poly(phthalazinone ether sulfone ketone)s support membranes were studied with various analyticalmethods such as infrared(IR)spectroscopy, scan electron microscopy (SEM), atomic forcemicroscopy (AFM), transmission electron microscopy(TEM), and X-ray diffraction techniques. The preparation process of composite membranes that have fully aromatic function layers (CM1)was optimized by orthogonal experiments. Results indicate that the polymerization should becarried out at 20℃for 30 seconds with 0.05wt.％chloride and 2wt.％diamine concentration andthe curing temperature should be 80℃. The composite membranes prepared at the optimizedcondition rejected 0.2wt.％NaCl solution by 98.3％and water flux was 27.8 L·m-2·h-1 at 1.2MPapressure, 50℃. When pressure rose to 2.1MPa and temperature rose to 90℃, NaCl rejection was98.1％while water flux improved to 98 L·m-2·h-1. The composite membranes that have alicyclicaromatic function layers (CM3) prepared at the optimized condition rejected 0.2wt.％Na2SO4 by98.4％and water flux was 58.3 L·m-2·h-1at 0.6MPa pressure, 25℃. CM3 membranes also rejectedCY, XG-6G and CV dyes by 100％, show good application prospect in water softening and dyerecycling fields.Influence of monomer structure on separation properties of the composite membranes wasstudied by contrasting separation properties of the composite membranes with different functionlayers. Results suggest that membranes prepared by acyl chloride and diamine monomers that areeasier to form crosslinked or dense packed function layers have higher salt rejection and lowerwater flux. Acid and alkali resistant of the composite membranes was studied by testing separationproperties of the membranes after treating with acid and alkali. Results indicate that acid and alkaliresistant of the composite membranes follows such sequence: fully aromatic＞aliphatic aromatic＞alicyclic aromatic. Thermal stability of support membranes and composite membranes was studiedby probing the relationship between solution temperature and separation properties. Resultsindicates: PPESK support membranes have superior thermal stability than PSF support membranes;with the same fully aromatic function layers, composite membranes supported by PPESKultrafiltration membranes have superior thermal stability than that supported by PSF ultrafiltrationmembranes; with the same PPESK support layer, thermal stability of the composite membranesthat have different function layers follows such sequence: fully aromatic＞alicyclic aromatic＞aliphatic aromatic.Relationship between separation performances of the composite membranes and operationparameters was investigated by the separation experiments of composite membranes with fullyaromatic, alicyclic aromatic and aliphatic aromatic function layers. Results indicate that under thesame condition, water flux of the series composite membranes increased lineally with the increaseof the operation pressure. When the operation pressure is relatively lower, salt rejection of thecomposite membranes increased with the increase of the operation pressure, but when the pressureincreased to a certain value, the salt rejection will remain almost the same when the operationpressure increased. With the increase of the salt concentration, both salt rejection and water flux ofthe series composite membranes declined. NaCl and Na2SO4 reflection coefficientσand solutepermeability p are calculated through irreversible thermodynamic model. Separation properties of the series composite membranes in varied salt concentration were predicted according to theirreversible thermodynamic model. Predictions agree with experimental data, which indicates thatwhen salt concentration varied, separation properties of CM1 composite membranes can bepredicted by the irreversible thermodynamic model. Membrane parameters such as effective poreradius rp, porosity/effective membrane thickness Ak/Δx and ion density X were calculated using theelectrostatic and steric-hindrance (ES) model according to the glucose and salt separationperformances of the composite membranes.
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