Study Of Preparation And Application Of Poly (Phthalazione Ether Nitrile Ketone) Composite Membranes

Poly (phthalazione ether nitrile ketone)(PPENK) was used as substrate material for thermally stable composite nanofiltration (NF) and reverse osmosis (RO) membranes because of its high glass-transition temperature (Tg,277℃), good chemical resistance, mechanical properties and cyanogroup with strong rigidity and polarity.Poly (piperazinamide)/PPENK composite NF membranes were prepared from piperazine (PIP) and trimesoyl chloride (TMC) on PPENK ultrafiltration (UF) membranes by interfacial polymerization. The optimal preparation parameters for composite NF membranes were as follows:the organic solvent was cyclohexane; TMC concentration=0.1%(w/v); PIP concentration=1.0%(w/v); reaction time=30s and immersion time in aqueous phase=1min. The rejection of the optimized membrane in1g/L Na2SO4solution reached99.6%and the flux was about57.9L/m2h when operation pressure was1.0MPa and operation temperature was20℃.Effects of heat treatment temperature and heat treatment time on the performance of chlorine-resistant Poly (piperazinamide)/PPENK composite NF membranes were studied. The chlorine-resistant performance of membranes increased with the increasing of heat temperature, However, the chlorine resistance of membranes decreased when heat temperature exceeded90℃. Moreover, composite NF membranes prepared by heat treatment time showed better chlorine-resistant performance compared to unheat treatment.Effect of operation temperature on the performance of poly (piperazinamide)/PPENK composite NF membranes was investigated. When operation temperature increased from20℃to80℃, the rejection of membranes in lg/L Na2SO4solution kept about97%, while the flux of membranes increased from43.0L/m2h to142.7L/m2h; the rejection of membranes in1g/L glucose solution decreased from93.1%to55.9%and the flux of membranes increased from52.4L/m2h to163.9L/m2h. Moreover, irreversible thermodynamic model and pore model were used to examine the thermally stable performance of Poly (piperazinamide)/PPENK composite NF membranes.σ kept about0.975when the feed solution was1g/L Na2SO4solution and the operation temperature increased from20℃to80℃, which can demonstrate that poly (piperazinamide)/PPENK composite NF membranes showed well thermal stability when inorganic salts were used as feed solutes. σ decreased from0.965to0.546and rp increased from0.398nm to0.591nm when feed solution was1g/L glucose solution and the operation temperature increased from20℃to80℃. When operation temperature increased from20℃to60℃, the increasing rate of pore size was30.7%when PPENK was used as substrate material, however, the increasing rate of pore size was33.3%when polysulfone was used as substrate material. In a word, poly (piperazinamide)/PPENK composite NF membranes showed well thermal stability.CH3COONa and reducing saccharides in mixed solution were separated by Poly (piperazinamide)/PPENK composite NF membranes. Effects of operation time, operation pressure, operation temperature and recovery rate on the solution separation performance of NF membranes were investigated. When cycling time increased from0h to5h, the flux of composite NF membranes decreased. However, while membranes were rinsed to de-ionized water for a certain time, the flux of membranes returned to original level. Therefore, membranes by rinsing in de-ionized water can keep better separation performance than rinsing in acid or alkaline solution.Polyamide/PPENK composite RO membranes were prepared from metaphenylene diamine and TMC on PPENK UF membranes by interfacial polymerization. Effects of operation conditions (such as operation pressure, feed solution concentration and operation temperature etc.) on the performance of composite RO membranes were also discussed. When the operation temperature increased from20℃to95℃, the rejection of membranes kept about98%, while the flux of membranes increased from7.4L/m2h to31.4L/m2h; The flux increased first then reached a plateau with the rejection of membranes kept constant when membranes in boiling de-ionized water were kept from0to3h. In a word, Polyamide/PPENK composite RO membranes showed well thermal stability. Effects of additions in aqueous solution on the performance of composite RO membranes were discussed. The results showed that the flux of RO membranes increased and the rejection kept stable when a certain amount of Triethylamine hydrochloride and Dimethyl sulfoxide were added in aqueous solution.