Study On Novel Poly(Phthalazinone Ether Nitrile Ketone) Hollow Fiber Ultrafiltration Membranes

Poly(phthalazinone ether nitrile ketone)(PPENK)is a novel membrane materials for uftrafiltration membranes with high glass-transition temperature,good solubility,well membrane-forming ability,hydrophylicity and good mechanical performance.The phase separation behavior of different nonsolvent additives in PPENK/NMP/NSA casting solution was studied with N-methyl-pyrrolidone(NMP)as casting solvent according to the linerized cloud point(LCP)correlation.It was found that each of the phase separation behavior for PPENK casting systems agree with the LCP correlation.The binodal lines of the three systems were calculated according to the LCP correlation.Therefore,the maximum content of NSA in the casting solution can be calculated according to the binodal lines of the system.The coagulation ability of the nonsolvent additives increased as follows: water＞glycol＞n-butylalcohol＞diethyleneglycol＞PEG400.PPENK hollow fiber uftrafiltration membranes with different separation performance were prepared by the dry-wet phase inversion technique with water as gel-bath.The effects of PPENK concentration,additive content,air gap distance,gel-bath temperature and fiber thickness during the membrane prepared process on the structure and property of PPENK hollow fiber ultrafiltration membranes were studied.The results showed that:the pure water flux increased with the decrease of the PPENK concentration,while the retention of PEG10000 decreased,885 L/(m²Â·h)for pure water flux was tested when the PPENK concentration was 11 wt.%;The structure and performance of membrane were changed with different addictive.The pure water flux of membrane increased when the EgOH content enhanced,while the retention of PEG10000 decreased a little,the excellent performance membrane was prepared when a =0.9 for EgOH content;With the aggrandizing of the air gap distance,the outer layer surface became more compact,the pure water flux of membrane decreased with the increase of the air gap distance,while the retention increased a little,the proper air gap distance was 1 cm;The pure water flux of membrane increased with the enhance of the gel-bath temperature,the proper gel-bath temperature was 21℃～25℃;The flux change rate diminished with thickening of the fiber thickness,the optimum range of fiber thickness was about 0.15～0.18mm. Finally,the performance of adsorption,compression resisting,heat resisting and chlorine tolerance were studied for PPENK hollow fiber uftrafiltration membranes.The test indicated that the retention of membrane was exactitude when test after operating 15min;The adsorption of membrane M₄ was more serious for PEG10000 than BSA;The molecular weight cut off of membranes were:M₁,3.6×10⁴;M₂,4.0×10⁴;M₃,5.2×10⁴;M₄, 6.0×10⁴;The PPENK hollow fiber uftrafiltration membrane can be used under 0.18MPa of compression and 88℃of operating temperature;The structure of membrane was well after dipping in the solution of NaClO at 400ppm,which indicated that the performance of chlorine tolerance for PPENK membrane was excellent.