醋酸纤维素中空纤维膜脱盐层的构建及膜脱盐性能研究
发布时间：2018-10-26 14:28
【摘要】：本文以二醋酸纤维素(CA)为成膜聚合物,N-甲基-2-吡咯烷酮(NMP)和脂类物质LA为混合稀释剂,聚乙二醇(PEG400)为成孔添加剂,采用复合热致相分离法(Complex Thermally Induced Phase Separation,c-TIPS)制备了CA平板膜和CA中空纤维膜。研究凝固浴温度和混合稀释剂质量比对CA平板膜结构与性能的影响,同时探究了纺丝工艺如纺丝温度、绕丝速度、气隙长度等对CA中空纤维膜结构与性能的影响。通过热处理、表面交联等后处理手段构建CA膜的脱盐层,探究热处理温度、交联温度、交联时间、醛类物质B溶液的质量分数等对CA膜结构与性能的影响。用扫描电子显微镜观察了CA膜横截面和表面形态,用电子万能试验机测试膜的拉伸强度,并用自制的水通量测试装置测定了CA膜的水通量和脱盐率,得到了本研究范围内最佳的铸膜液配方、纺丝工艺和表面交联工艺。研究结果表明,随着凝固浴温度提高,CA平板膜出现越来越多的指状孔结构,凝固浴温度降低到10℃,可以有效的减少指状孔结构。调节混合稀释剂的质量比,能够控制CA平板膜的孔结构,当NMP/LA的质量比为8:2时,制备出皮层较薄、支撑层为双连续网状孔,膜孔孔径大小呈梯度分布的CA平板膜;进一步优化混合稀释剂的质量比,NMP/LA的质量比为8.2:1.8时,CA平板膜的形貌结构更加完善,CA平板膜的水通量和脱盐率分别为28.27 L/(m2·h)、15.43%,拉伸强度是4.05 MPa。在纺丝工艺中,提高纺丝温度制备的CA中空纤维膜脱盐率有一定的升高趋势,而水通量急剧下降,喷丝头温度为130℃时,CA中空纤维膜横截面形貌结构变差,体系的纺丝稳定性差;气隙长度的增加,CA中空纤维膜指状孔变少,形貌结构越来越完善,膜丝的水通量降低而脱盐率升高;而提高绕丝速度,对CA中空纤维膜的脱盐率影响较小,有助于水通量和拉伸强度的提高;在喷丝头温度100℃、气隙长度为10 cm,绕丝速度100 m/min的工艺条件下,CA中空纤维膜的水通量为15.06 L/(m2·h),脱盐率为62.34%。为进一步提高CA膜的渗透和脱盐性能,构建CA膜更加致密的脱盐层,采用缩醛化表面交联反应,在交联温度95℃、醛类物质B溶液质量分数12%、交联时间40min的交联工艺条件下,CA平板膜的脱盐率为95.68%,水通量为9.85 L/(m2·h),而CA中空纤维膜的脱盐率为83.26%,水通量为6.09 L/(m2·h),CA中空纤维膜的脱盐性能了较大的提升。
[Abstract]:In this paper, cellulose diacetate (CA) was used as film forming polymer, N-methyl-2-pyrrolidone (NMP) and lipids (LA) were used as mixed diluents and polyethylene glycol (PEG400) as pore forming additive. The composite thermal phase separation (Complex Thermally Induced Phase Separation,) method was used. CA flat membrane and CA hollow fiber membrane were prepared by c-TIPS. The effects of coagulation bath temperature and mass ratio of mixed diluents on the structure and properties of CA flat membrane were studied. The effects of spinning process such as spinning temperature, spinning speed and air gap length on the structure and properties of CA hollow fiber membrane were investigated. The desalination layer of CA membrane was constructed by heat treatment and surface crosslinking. The effects of heat treatment temperature, crosslinking time and mass fraction of aldehyde B solution on the structure and properties of CA membrane were investigated. The cross section and surface morphology of CA membrane were observed by scanning electron microscope (SEM), the tensile strength of the membrane was measured by electronic universal testing machine, and the water flux and desalination rate of CA membrane were measured by a self-made water flux test device. The optimum casting solution formulation, spinning process and surface crosslinking technology were obtained. The results show that with the increase of coagulation bath temperature, more and more finger pore structures appear in CA flat film, and the decrease of coagulation bath temperature to 10 鈩，
本文编号：2296033
[Abstract]:In this paper, cellulose diacetate (CA) was used as film forming polymer, N-methyl-2-pyrrolidone (NMP) and lipids (LA) were used as mixed diluents and polyethylene glycol (PEG400) as pore forming additive. The composite thermal phase separation (Complex Thermally Induced Phase Separation,) method was used. CA flat membrane and CA hollow fiber membrane were prepared by c-TIPS. The effects of coagulation bath temperature and mass ratio of mixed diluents on the structure and properties of CA flat membrane were studied. The effects of spinning process such as spinning temperature, spinning speed and air gap length on the structure and properties of CA hollow fiber membrane were investigated. The desalination layer of CA membrane was constructed by heat treatment and surface crosslinking. The effects of heat treatment temperature, crosslinking time and mass fraction of aldehyde B solution on the structure and properties of CA membrane were investigated. The cross section and surface morphology of CA membrane were observed by scanning electron microscope (SEM), the tensile strength of the membrane was measured by electronic universal testing machine, and the water flux and desalination rate of CA membrane were measured by a self-made water flux test device. The optimum casting solution formulation, spinning process and surface crosslinking technology were obtained. The results show that with the increase of coagulation bath temperature, more and more finger pore structures appear in CA flat film, and the decrease of coagulation bath temperature to 10 鈩，
本文编号：2296033
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