Study On Thermal Stable Poly(Phthalazinone Ether Amide) Ultrafiltration Membrane And Composite Membranes

Poly(phthalazinone ether amide) (PPEA) is a candidate for membrane materials with high glass-transition temperature (329℃), good solubility, hydrophilicity, chemical resistance, mechanical properties and well membrane-forming ability.PPEA flat-type ultrafiltration(UF) membranes with different separation properties were prepared by phase-inversion method with N, N-dimethylacetamide (DMAc) as solvent, water as coagulant, ethylene glycol monomethyl ether, ethylene glycol, ether, diethyleneglycol and polyethylene- glycol(PEG) 400 as non-solvent additive, separately. The effects of polymer concentration, the type and amount of additive, evaporation time, the temperature of the coagulant bath on the pore structure and performance of the membranes were studied in detail. UF membranes with rejection capacity in the range of PEG2000^PEG20000 and with pure water flux of 43 L·m^-2·h^-1～695 L·m^-2·h^-1 were obtained, when tested at 25℃, O.lMPa. PPEA UF membranes were also prepared on the support of non-woven fabric with a casting machine. PPEA UF membrane was applied in the desalination-purification experiment for four dyes, which was effectively accomplished at 0.3MPa,80℃. Only after three cycles of constant volume desalination-concentration experiment, about 150 minutes, salt mixed in dye was fully removed. After 6 hours of desalination-concentration experiment at 80℃, the rejection for dyes was kept constant and the flux only showed a marginal decrease, which is less than 10 L·m^-2·h^-1.Composite membranes were prepared through interfacial polymerization of active monomers on the surface of PPEA UF membrane. The effect of monomers in aqueous phase on the chemical structure and congeries structure of the active layer polymer, the surface morphology and separation performance of the composite membrane was studied. The polyamide polymer of the active layer is partly crystallized when prepared through the interfacial polymerization of m-phenylene diamine (MPD) aqueous solution and trimesoyl chloride (TMC) hexane solution. While the polymers prepared with piperazine (PIP) and TMC is amorphous. The relative roughness of the membrane surface increased with the increase of the MPD/PIP proportion in aqueous phase, while the rejection of the composite membrane increased and the flux decreased at the same time.High temperature resistant reverse osmosis (RO) composite membrane was prepared through the interfacial polymerization of MPD aqueous solution and TMC hexane solution.