Preparation And Application Of PMIA/SPEEK Blend Nanofiltration Membrane

Nanofiltration separation with its unique characteristics has been widely used in drinking water purification, food and pharmaceutical wastewater, textile printing and dyeing wastewater treatment, etc. Research and development of new type of nanofiltration membrane have become the hot spot in the field of new membrane separation technology. However, most of the nanofiltration membranes in China are dependent upon importation from foreign countries and the research in this filed started late. The researchon the development of new nanofiltration membrane has attracted much attention because of its significance for the development of the nanofiltration industry and the economy.Aromatic polyamide is an excellent polymer membrane material because of its good thermal and chemical stability. Due to its excellent hydrophilicity and charge, Sulfonated poly(ether ether ketone) is often applied as an additive in membrane research with other polymer blend, in order to improve the performance of the membrane. Nanofiltration membrane was prepared usingpolyisophthaloyl metaphenylene diamine(PMIA)and sulfonated poly(ether ether ketone)(SPEEK) as the raw materials by the method of immersion-precipitation phase transformation.. The following results have been achieved:1. This research has studied the effects of PMIA and SPEEK concentration, organic additives, inorganic additives content, evaporation time and coagulation bath temperature on the structure and performance of the PMIA/SPEEK blending nanofiltration membrane.A series of nanofiltration membrane with different morphology and properties was prepared based on the composition of casting solution and the membrane process optimization, providing a theoretical basis of preparation of new PMIA/SPEEK blending nanofiltration membrane.2. Characterization of the newly prepared membrane showed that the membrane had a typical asymmetric structure and presented strong burden electrical, good pressure tightness, acid and alkali. The intercept molecular weight was around 900, pore size distribution was controlled in 2 nm. It posed a good interception of small organic molecules; The interception of inorganic salts was Na2SO4 > MgSO4 > Na Cl > MgCl2, conforming to the general characteristics of nanofiltration membrane.3. Simulation removal of wastewater containing Cr(VI) showed that the homemade PMIA/SPEEK blending nanofiltration membrane had a good effect on Cr(VI) removal. The removal efficiency was mainly above 96%, Removal performance was not affected by the operating pressure and slurry concentration; But pH of the wastewater had great effect on the removal efficiency. When pH > 7, Cr(VI) mainly existed in the form of CrO42-, the removal rate could reach above 98%.