表面改性纳米氧化铝亲水共混膜制备及其水处理效能

经低温等离子体处理后,在纳米氧化铝(Al2O3)表面接枝甲基丙烯酸-2-轻乙酯(HEMA)或其聚合物,制备了Al2O3-g-HEMA纳米复合颗粒。采用纳米Al2O3Al2O3-g-HEMA纳米复合颗粒分别与聚偏氟乙烯(PVDF)共混,制备了PVDF/Al2O3膜和PVDF/Al2O3-g-HEMA膜,并与未改性PVDF膜进行比较。考察了改性纳米Al2O3表面的接枝情况和平均粒径,以及上述3种超滤膜处理聚驱采油废水的通量、出水水质及膜污染情况。结果表明,经表面改性的纳米Al2O3,其颗粒团聚得到良好控制,平均粒径大幅下降。PVDF/Al2O3膜和PVDF/Al2O3-g-HEMA膜的亲水性、纯水通量、处理聚驱采油废水的运行通量及清洗后通量恢复率均大幅提高。3种膜对聚丙烯酰胺、油类和TOC均有良好的去除效果,且共混改性不影响膜对大分子物质的去除。以PVDF/Al2O3-g-HEMA纳米复合颗粒作为添加剂制备的共混膜,其通量、去除效果和抗污染能力等综合性能最佳,是深度处理聚驱采油废水的理想膜材料。

Preparation of Hydrophilic Mixed Matrix Membrane Blended with Surface Modified Alumina Nanoparticles and Its Water Treatment Efficiency

Al2O3-g-HEMA nanocomposites were prepared by grafting HEMA or its polymers onto the surface of alumina nanoparticles through low temperature plasma. Two kinds of modified PVDF ultrafiltration membranes were prepared by blending alumina nanoparticles or surface modified alumina nanoparticles in the membrane matrix. The raw PVDF ultrafiltration membrane without nanoparticles were set as the control group. The graft efficiency and the extent of reduction on nanoparticle agglomeration was evaluated. The change of flux, permeate quality and membrane fouling of the prepared membranes were also investigated when applied in polymer flooding wastewater treatment. Results showed that a good graft effect had been achieved. The surface modified alumina nanoparticles had a significant drop on the average particle diameter, which meant an evident decrease on the nanoparticle agglomeration. The hydrophilicity and pure water flux of PVDF/Al2O3 mixed matrix membranes and PVDF/Al2O3-g-HEMA mixed matrix membranes were significantly higher. Meanwhile, the operation flux and the recovery ratio after physical cleaning were enhanced in treating polymer flooding wastewater. All the modified membranes prepared shared similarly good performance in the treatment of polymer flooding wastewater compared to the control group. Analysis and comparison on the molecular weight of contaminants in the influent and effluent proved an unaltered removal efficiency of macromolecule for the modified membranes. PVDF membranes blended with Al2O3-g-HEMA nanocomposites shows best comprehensive performance in flux, rejection ability and anti-fouling property. It is a superior membrane material in advanced treatment of polymer flooding wastewater.