Poly(Phthalazione Ether Nitrile Ketone) Thermally Stable Composite Membranes

The separation of high temperature fluid and the demands of seawater desalination need a new type of thermally stable composite membranes foe reverse osmosis.Poly(phthalazione ether nitrile ketone)(PPENK)could be used as the material for the fabrication of thermally stable composite membranes due to the high glass-transition temperature(T_g,277 ~oC)and cyanogroup with strong rigidity and polarity.Firstly we perpared the PPRNK ultrafiltration(UF)membranes with low molecular weight cut off(MWCO).And studied the effects of PPENK concentration on MWCO.When the casting solution concentration of PPENK increased,MWCO of PPENK UF membranes decreased,pore size distribution getting better.Then,we fabricated the PPENK composite membrane by interfacial polymerization with MPD and TMC.Studied the effects of the pore size and pore size distribution of PPENK UF membranes,monomers concentration ratio(MPD/TMC),reaction time,immersion time,heat treatment temperature and heat treatment time on composite membranes.When the MWCO of PPENK UF membrane was 55.0 K Da,monomers concentration ration was 10:1,reaction time was 10 s,immersion time was 20 s,heat treatment temperature was 40 ~oC,heat treatment time was 4 min,the retention of RO membrane was 86.27%for 2000 ppm NaC l solution.The flux was 4.62 L/m~2?h.And it was the best preparation conditions.Final,we had preliminary study on the thermally stable performance of the composite membranes.As the operating temperature increased from 30 ~oC to 88 ~oC,the retention decreased from 88.77%to 84.41%,and the flux increased from 4.26 L/m~2?h to 22.70 L/m~2?h,which can demonstrated that PPENK can be used as the material to fabricate the thermally stable composite membranes.