界面聚合法制备亲水性复合纳滤膜及在稀土回收中的应用研究

发布时间：2018-10-07 17:41

【摘要】：本论文将以相转化法制备的超滤膜为支撑层,再以界面聚合反应生成的超薄功能层为复合层来制备具有较高通量的亲水性复合纳滤膜,并将其用于稀土回收中,探究其最佳的操作条件。研究内容包括以下三部分:以聚砜(PSF)为膜材料、聚乙二醇(PEG-600)和聚乙烯基吡咯烷酮(PVP-K30)为添加剂、N-N二甲基乙酰胺为溶剂,采用相转化法制备超滤膜。实验研究了不同浓度的PSF及PEG-600、PVP-K30添加剂含量对超滤膜性能的影响规律,并得出作为支撑层的超滤膜的最佳制备条件为:PSF含量15%-17%,PEG-600含量为1.5%-2.5%,PVP含量为4%-6%。该条件下获得的超滤膜在0.1MPa压力下的纯水通量为247-372L/m2·h,对浓度为1g/L牛血清蛋白溶液截留率为93.5%至99.4%。以哌嗪(PIP)和均苯三甲酰氯(TMC)分别为水相和有机相单体,以相转化法制备的超滤膜为基膜,采用界面聚合法制备亲水性复合纳滤膜。实验研究了界面聚合反应中水相单体浓度、有机相单体浓度、酸接收剂磷酸钠添加量、界面聚合反应时间、热处理温度及时间等对复合纳滤膜性能的影响规律,得出亲水性复合纳滤膜的最佳制备工艺为:PIP浓度为1%-1.5%,TMC浓度为0.25%-0.3%,磷酸钠浓度为1%-2%,水相反应时间为60-70s,有机相反应时间为55-65s,热处理温度为70-80℃,热处理时间为8-12min。在该条件下制得的亲水性复合纳滤膜在0.6MPa下的纯水通量最高可达36.78 L/m2·h,对浓度为1g/L Mg SO4的截留率均在94%以上。此外,复合纳滤膜的SEM表征、AFM表征及亲水性表征显示磷酸钠的加入有效的提高了复合纳滤膜的有效膜面积及亲水性。该复合纳滤膜对不同价态盐离子的截留顺序依次为Na2SO4(94.76%)≈Mg SO4(94.54%)Mg Cl2(78.66%)Na Cl(42.5%),且适当增大操作压力将有助于提高膜通量及截留率。为考察所制亲水性复合纳滤膜的实际应用性能,将其用于低浓度稀土浸出液中回收稀土离子的应用研究。实验发现,该复合纳滤膜对稀土离子的截留率可达93%以上,且适当提高进料温度及操作压力可以提高截留率和通量。在1MPa压力下,该复合纳滤膜对初始浓度为0.33g/L的稀土原液进行8小时的浓缩,即可使其浓度提高到3.48倍,渗透液中稀土离子浓度仅为0.015g/L。由此可以看出,该复合纳滤膜对稀土离子具有较好的截留性能,在稀土回收中将有很好的应用前景。
[Abstract]:In this paper, the ultrafiltration membrane prepared by phase inversion method is used as the supporting layer, and the ultrathin functional layer generated by interfacial polymerization is used as the composite layer to prepare the hydrophilic composite nanofiltration membrane with high flux, and it is used in the recovery of rare earths. Explore the best operating conditions. The research contents are as follows: ultrafiltration membrane was prepared by phase inversion method using polysulfone (PSF) as membrane material, polyethylene glycol (PEG-600) and polyvinylpyrrolidone (PVP-K30) as additives, N-N dimethyl acetamide as solvent. The effects of different concentrations of PSF and PEG-600,PVP-K30 additives on the performance of ultrafiltration membrane were studied. The optimum preparation conditions of ultrafiltration membrane were obtained as follows: 15% PSF content and 1.5 -2.5% PEG-600 content. Under this condition, the pure water flux of the ultrafiltration membrane obtained under 0.1MPa pressure is 247-372L/m2 h, and the rejection rate of 1g/L bovine serum protein solution is 93.5% to 99.4%. Hydrophilic composite nanofiltration membranes were prepared by interfacial polymerization with piperazine (PIP) and trimethoyl chloride (TMC) as aqueous and organic monomers and ultrafiltration membranes prepared by phase inversion method. The effects of water monomer concentration, organic monomer concentration, acid receiver sodium phosphate addition, interfacial polymerization time, heat treatment temperature and time on the properties of composite nanofiltration membrane were studied experimentally. The optimum preparation process of hydrophilic composite nanofiltration membrane was obtained as follows: 1% PIP concentration 1-1.5 and TMC concentration 0. 25-0. 3, sodium phosphate concentration 1-2 and water phase reaction time 60-70 s, organic phase reaction time 55-65 s, heat treatment temperature 70-80 鈩，

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