Preparation Of Novel PMIA Nanofiltration Membrane And Its Application In Water Treatment

This article uses the polymer PMIA as nanofiltration membrane material, studythe preparation of a new type of flat polyamide nanofiltration membrane. Then itsapplication in the separation of new persistent organic pollutants in drinking water:perfluorooctane sulfonate (PFOS) removal experiment study. Nanofiltration factorsstudied in different operating conditions, such as the impact of the removal of PFOS.The main conclusions as fllows:1. Preparation and properties of flat aromatic polyamide nanofiltration research.Asymmetric flat sheet PMIA membranes Polyamide polymer were prepared by phaseinversion method. The effects of different factors, such as PMIA concentration, thekinds of additive composition, process conditions were systematically investigated toobtain the optimal technique parameters.Bydetermining the best composition ofcasting solution and film forming process parameters, and the system performanceand microstructure of interception of nanofiltration membrane structures are analyzed.The results indicated that membranes with the rejection of500mg/l Na2SO4solutionrate was reached53.93%, the interception of100ppb PFOS intercept rate wasreached80.4%, the flux reached50.57l/(h·m2)under1.0MPa at25℃2. Effect of activated carbon nanoparticles concentration on PMIA NFmembrane performance. The aromatic poly (m-phenylene isophthalamide)(PMIA)nanofiltration (NF) membrane with active carbon nanoparticles (ACNP) as additiveswas fabricated by phase inversion.The experimental results show that Nanofiltrationmembrane consists of a porous layers as sponge and the epidermal layer becamedense when the carbon nanoparticles (ACNP) content increase.Especially when theadding amount of active carbon nanoparticles (ACNP)was0.5%, nanofiltrationmembrane for concentration of100ppb PFOS intercept rate reached80%-90%,andthe performance is better than that of without adding ACNP. That suggests addingactive carbon nanoparticles(ACNP)in PMIA composite nanofiltration membrane caneffectively remove the PFOS in the water.That suggests adding active carbonnanoparticles(ACNP)in PMIA composite nanofiltration membrane can effectively remove the PFOS in the water.3. The effects of operating pressure, pH, the initial concentration of PFOS andmembrane flux were investigated. The rejection mechanism was also analyzed. Theresults showed that with increasing pressure, the membrane flux and PFOS rejectionrate increased. PFOS rejection rate increased as pH, PFOS initial concentrationincreased. The removal mechanism of PFOS from water was mainly sieving effectand charge effects.4. The impact of electrolyte such as Ca2+and Mg2+on the rejection of PFOS wasinvestigated. The effect of calcium ions and magnesium ion on the nanofiltrationperformance was studied in detail, and the retention mechanism was analyzed. Therejection of PFOS and membrane flux were elevated with the calcium concentrationincreased, but the flux reduced when the concentration increases to a certain extent of3mmol/l. The effects of calcium mainly have two reasons, one is the screening effectimproves as PFOS may complexed with Ca2+or Mg2+, the other is Donnan effect.When joining a certain concentration of magnesium ions in the solution, membraneflux decline after rising first, this is due to the hydration of magnesium ions.