Investigation On The Preparation And Performance Of PSF/Nano-Mg（OH）₂ Composite Membrane

In order to make polysulfone/nano-Mg（OH）₂ composite ultrafiltration membrane, L-S phase inversion was used, polysulfone and nano-Mg（OH）₂ were chosen as raw material,and actone, PVP were chosen as additive, and two kinds of polyelectrolytes, PSS and PDADMAC, were selected to investigate on polysulfone/nano-Mg（OH）₂ composite ultrafiltration membrane by static layer-by-layer self-assembly methods preparation process. Concentration of nano-Mg（OH）₂, mechanical stirring time, pH and so on were studied to analyze the influence on preparation of polysulfone/nano-Mg（OH）₂ composite ultrafiltration membrane, and FE-SEM, XRD, atomic force microscopy（AFM） were chosen to analyze membrane surface morphology and elemental component, treatment and resources of heavy metal high ammonia wastewater were investigated on experiment.Based on the research, it was showed that the rejection of PEG2000 as high as 85.4%and water flux as 60.7L/m2·h when the nano-Mg（OH）₂ content was 0.8%, the mechanical stirring time was 24 h, the membrane thickness was 0.70 mm, operating pressure was0.1MPa, respectively. The results show that the polysulfone/Nano-Mg（OH）₂ composite ultrafiltration membranepossesses with thermal stability in the range of 40-160℃; The surface of the polysulfone/Nano-Mg（OH）₂ composite ultrafiltration membrane and the possesses properties were analyzed using FE-SEM and X-ray diffraction spectrum（XRD）and EDS. The surface of the polysulfone/Nano-Mg（OH）₂ composite ultrafiltration membrane surface was smooth, dense,uniform and the uniform distribution of the nano-Mg（OH）₂ in a cross section made ultrafiltration membrane have good hydrophilic and penetrating. The polysulfone/nano-Mg（OH）₂ composite nanofiltration membrane was prepared successfully by static layer-by-layer self-assembly methods, and result shows the best condition was the six pairs of layers,and while the supporting electrolyte were selected NaCl and MgCl2 with the concentration were 0.5mol/L. Under the optimal conditions, the rejection of the Na2SO4 with the concentration was 2g/L could reach 88.6% and flux could reach 50.6L/m2·h while the pressure was 0.4MPa, while the concentratiostatic layer-by-layer self-assembly methods, the rejection could only 9.9% for the NaCl, and the flux could reach 70.6L/m2·h. This result shows that polysulfone/Nano-Mg（OH）₂composite nanofiltration membrane could be used for a monovalent, divalent salts of separation. while the Cu2+ and Zn2+ were difficult to separate. Feed concentration,operating pressure, feed flow were three important factors, The experimental exploration results showed that the rejection of the three ions can reach 98.7%, 99.5% and 5.6%,respectively, and flux is about 55L/m2·h under optimal conditions while the operating pressure was 0.4MPa, the feed flow rate was 10L/min.