聚砜-纤维素复合超滤膜材料的制备与表征

以聚砜为原材料,通过向铸膜液中混入纤维素微纳晶体,采用浸没沉淀相转化工艺制备了纤维素填充聚砜基复合超滤膜材料。通过正交试验分析了各因素对产品性能的影响并得出了制备复合超滤膜的最优条件:当聚砜质量分数为18%,添加剂聚乙烯吡咯烷酮(PVP K30)为0.3%,纤维素微纳晶体加入量为聚砜质量的15%,空气中溶剂蒸发时间为10s,然后在凝胶浴水中凝胶成形。并测定复合超滤膜的水通量、截留率、平均孔径、孔隙率、强度等一系列性能,膜的水通量为152.72L/(m²·h),截留率为93.98%,孔隙率为63.22%,平均孔径为46.03nm,膜具有良好的综合性能。     

纤维素/聚砜复合超滤膜表征与凝胶特性

通过向聚砜铸膜液中加入微纳纤维素,以浸没沉淀相转化工艺制备微纳纤维素/聚砜复合膜材料,并对复合膜的水通量、截留率、孔隙率、平均孔径进行测定.采用扫描电子显微镜对膜孔结构进行观察,利用浊点滴定实验得到的三元相图对其凝胶特性进行了研究.结果表明随着微纳纤维素加入量的增大,复合膜水通量逐渐增大、截留率保持在较高的水平,孔隙率逐渐增大,平均孔径略有增加.微纳纤维素的存在,改变了铸膜液的分相途径和浊点的组成,从而影响了膜孔结构和复合膜性能.     

聚偏氟乙烯/纳米纤维素复合超滤膜的研究

以聚偏氟乙烯为原材料,聚乙烯吡咯烷酮( PVP K30)为添加剂,并向聚偏氟乙烯铸膜液中混入纳米纤维素,采用相转化工艺制备了复合超滤膜.通过正交试验分析了各因素对产品性能的影响,并得出了制备复合超滤膜的最优条件:聚偏氟乙烯质量分数为14％,添加剂PVP K30质量分数为0.5％,纳米纤维素加入量为0.7％,空气中溶剂蒸发时间为10s,凝胶浴为水.测定复合超滤膜的水通量、截留率、平均孔径、孔隙率、力学强度等一系列性能,膜的水通量为40.7 L/(m2·h),对牛血清蛋白的截留率为91.8％,孔隙率为52.3％,平均孔径为15.3 nm.     

聚砚基纤维素填充复合超滤膜材料的研究

以聚砜为原材料,通过向铸膜液中混入纤维素微纳晶体,采用浸没沉淀相转化工艺制备了纤维素填充聚砜基复合超滤膜材料。测定了超滤膜的水通量、截留率、平均孔径、孔隙率等性能,通过单因素影响试验分析了各个工艺因素对产品性能的影响;考察了膜的化学稳定性以及运行压力对性能的影响;通过扫描电镜观察了膜孔的结构;并通过浊点滴定实验得到膜液的三元相图,分析了纤维素的加入对成膜过程的影响。     

聚砜中空纤维膜的亲水改性研究

将吐温80或磺化聚砜(SPSF)加入聚砜-聚乙二醇400-二甲基乙酰胺(PSF–PEG400–DMAc)体系,共混制成均一铸膜液,采用浸入沉淀相转化法制备聚砜中空纤维超滤膜,考察吐温80或SPSF对聚砜中空纤维膜的亲水改性效果。对膜结构、铸膜液黏度、纯水通量、截留率、拉伸强度等进行了表征。研究结果表明,SPSF相比吐温80对膜的亲水性改善更明显。当SPSF质量分数为1.5%时,就可将PSF中空纤维膜的纯水通量提高一倍以上,膜纯水通量达到302 L/(m~2·h),对牛血清白蛋白(BSA)的截留率达到93%。     

凝胶成份对PVDF/PVP中空纤维超滤膜结构与性能的影响

采用干-湿相转化法制备PVDF/PVP共混中空纤维超滤膜,通过改变内外凝胶浴组成控制膜的结构和性能,使用扫描电镜对不同凝胶条件下膜的微观形貌和结构进行了表征,以纯水通量和BSA截留率评价膜性能.结果表明,芯液中溶剂质量分数由10％升高至50％会使膜孔收缩,膜通量下降;芯液中甘油质量分数由10％升至30％后能使膜形成大孔结构,使通量增大.凝胶浴中溶剂质量分数高于40％,会使聚合物溶解,但加入质量分数1％的醋酸能降低高浓度溶剂的溶解作用,使通量升高.     

低截留分子质量新型聚芳醚腈酮超滤膜的研制

以新型聚芳醚腈酮为膜材料 ,以N -甲基 - 2 -吡咯烷酮 (NMP)为溶剂 ,研究了聚合物浓度、添加剂种类及含量、凝胶浴温度等对超滤膜性能的影响。结果表明 ,聚合物质量分数以 1 2 %～ 1 3 %为合适的制膜浓度 ,以聚乙二醇PEG - 4 0 0为添加剂时获得了高截留率和高水通量的超滤膜。随着凝胶浴温度的升高 ,水通量明显增大 ,而截留率有所下降 ,而共聚物的浓度增加则有相反的效果。制得的超滤膜具有较低的截留分子量 (PEG- 2 0 0 0 ) ,将制得的超滤膜用于达旦黄、黄X-G等染料的分离 ,截留率均达 90 %以上     

铸膜液中水含量对聚砜超滤膜结构和性能的影响

试验在环境温度20℃、相对湿度50%、凝胶浴温度20℃的条件下制膜,在聚砜(PS)铸膜液中添加水为非溶剂添加剂,研究水添加量对铸膜液粘度、膜性能和结构的影响.结果表明,水的添加对铸膜液起到了增粘的作用;30℃ PS的质量分数为14%铸膜液所成膜的纯水通量随铸膜液中水的添加量的增加大体上呈增加的趋势,从59.1增大到126.4 L·m~(-2)·h~(-1);截留率则略有下降;相应的膜表面的孔径增大、孔增多;相同水添加量(质量分数0.05%)PS的质量分数为14%的铸膜液粘度随温度的升高而减小;铸膜液温度的升高,相应的膜的纯水通量随之增加,截留率则略有下降.     

一种新型共混复合纳滤膜的制备及性能研究

以海藻酸钠(ALG)和羧甲基纤维素钠(CMC)共混液为活性层铸膜液,聚砜(PSF)超滤膜为基膜,环氧氯丙烷(ECH)的乙醇溶液为交联剂,采用涂敷和交联的方法制得一种新型复合纳滤膜,利用红外光谱仪、扫描电子显微镜、原子力显微镜和接触角测量仪等检测手段对复合膜进行了结构和性能的表征。结果表明,在1.0 MPa压力和30 L?h-1料液流量操作条件下,该复合纳滤膜对1000 mg?L-1 Na2SO4溶液的截留率为97.1%,通量17.3 L?m-2?h-1。以ALG和CMC共混液制备的复合纳滤膜比单一材料膜有更致密的膜面结构,截留率更高。该纳滤膜对不同无机盐的截留性能不同,表现出荷负电膜截留性能,这主要决定于荷电膜与电解质离子之间的静电作用力。     

PVDF-PAN-纳米粘土杂化中空纤维超滤膜纺丝工艺研究

以聚偏氟乙烯和聚丙烯腈为主要膜材料、N,N-二甲基乙酰胺为溶剂、无水LiCl和有机纳米粘土为添加剂,采用干-湿相转化法纺丝工艺制备杂化中空纤维超滤膜,研究了干程、外凝胶浴温度、芯液温度和组成等纺丝工艺参数对杂化膜微观结构和分离性能的影响.SEM观察发现,中空纤维膜有较致密的外表面和多孔的内表面,干程对膜的横截面结构和表面形态都有影响:增加芯液含量有利于抑制大孔结构的产生,使孔径变小,结构致密,芯液为质量分数40%无水乙醇时,制得的膜对BSA截留率达到99%.试验结果表明,在较高的凝胶浴温度和较大的干程下制得的膜有较高的水通量和较低的截留率;凝胶浴温度升高,膜的力学性能加强,铸膜液中聚合物的质量分数为16%时,最大拉伸强度为3.16 MPa.     

凝固浴温度对PVDF/PES-C共混膜结构及性能的影响

以邻苯二甲酸二丁酯(DBP)和N,N-二甲基乙酰胺(DMAc)为混合稀释剂,采用热致相分离法(TIPS)制备了聚偏氟乙烯(PVDF)/酚酞型聚醚砜(PES-C)共混膜,考察了不同凝固浴温度对膜结构和性能的影响。采用扫描电镜观察了膜的结构,测试了膜的纯水通量。运用DSC和XRD方法检测了膜的结晶性能。将制备的膜在膜生物反应器(MBR)中运行测试了膜的污水通量和出水指标。随凝固浴温度的升高,共混膜的最高熔融温度上升,膜中α晶型的含量增加。在凝固浴温度为25℃时,膜形成了较为致密的皮层结构和较为疏松的支撑层结构,此时共混膜的纯水通量和污水通量达到最大值,且MBR出水COD和NH4+-N含量达到排放要求。     

Synthesis and characterization of bacterial cellulose/alginate blend membranes

Bacterial cellulose and alginate in an aqueous NaOH/urea solution were used as substrate materials for the fabrication of a novel blend membrane. The blend solution was cast onto a Teflon plate, coagulated in a 5 wt % CaCl₂ aqueous solution, and then treated with a 1% HCl solution. Supercritical carbon dioxide drying was then applied for the formation of a nanoporous structure. The physical properties and morphology of the regenerated bacterial cellulose and blend membranes were characterized. The blend membrane with 80% bacterial cellulose/20 wt % alginate displayed a homogeneous structure and exhibited a better water adsorption capacity and water vapor transmission rate. However, the tensile strength and elongation at break of the film with a thickness of 0.09 mm slightly decreased to 3.38 MPa and 31.60%, respectively. The average pore size of the blend membrane was 10.60 Å with a 19.50 m²/g surface area. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

纳米晶体纤维素Ⅱ的制备与表征研究

用硫酸水解棉短绒得到的纳米晶体纤维素Ⅰ(NCC-Ⅰ),经1%的NaOH处理后就可得到纳米晶体纤维素Ⅱ(NCC-Ⅱ)。用X-射线衍射仪、TEM、AFM、FITR和GPC表征,证明NCC-Ⅰ有低的分子量、窄的分子量分布及较高的化学活性;在FTIR谱中,NCC-Ⅰ的羟基波数较之棉短绒的羟基波数有明显的蓝移现象。研究证明纳米晶体纤维素具有十分明显的纳米效应。     

凝固浴组成对NMMO法纤维素膜形貌的影响

为实现对分离用纤维素膜形貌的控制,采用NMMO法,分别以水、甲醇、乙醇和由它们配制的双组分溶液为凝固浴,制备了纤维素膜,观察了干膜的表面和断面形貌,测定了湿膜的孔结构参数,在对比基础上分析了干膜中微孔的形成过程与机制,探讨了纤维素结晶尺度与湿膜平均孔径的相关性和影响因素.研究表明,不同凝固浴制备出的纤维素膜在干态形貌上差别明显.纤维素膜的湿态孔隙率基本不受凝固浴组成影响,而干态下的致密区域在水溶胀后呈现多孔结构,对湿膜平均孔径影响很大.通过改变凝固浴组成,可分别或协同地调控纤维素膜的干态或湿态结构.     

Study on the control of pore sizes of membranes using chemical methods: Part III. The performance of carbonates and bicarbonates in the membrane-making process by the chemical reaction

In this paper, polyvinylidene fluoride (PVDF)/polymethyl acrilate (PMMA)/cellulose acetate (CA) blend UF membranes were prepared by chemical reaction introduced phase-inversion method. The results of the experiment show that: (1) The membrane pore size distribution is more uniform due to the presence of carbonates or bicarbonates in the coagulation bath; (2) No more than the stoichiometric ratio amount of carbonates or bicarbonates in the coagulation bath can effectively improve the membrane pore size distribution and make the pore size of membrane more uniform; (3) The membrane prepared by carbonates solution as a working solution in coagulation bath possess superior performance than that by bicarbonates.     

Preparation and characterization of dense cellulose film for membrane application

Regenerated cellulose films were prepared with environmentally friendly process by utilized N‐methylmorpholine‐N‐oxide (NMMO)‐Cellulose system. To prepare a dense cellulose film for membrane application, some parameter process which influence porous forming such as cellulose DP, cellulose concentration, addition NMMO in coagulation bath, coagulation bath temperature, and drying condition were investigated. We resumed that the porosity and pore size of cellulose membrane decrease with lower cellulose DP, higher cellulose concentration, addition of NMMO in coagulation bath, applying room temperature in coagulation bath and drying, and applying vacuum on drying process resulted in membranes with porosity in range of 24–41% and pore size 13.4–20.2 nm. The main factor for controlling porosity and pore size of dense cellulose membrane was coagulation process condition especially addition of NMMO into coagulation bath. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of mesh-reinforced cellulose acetate forward osmosis membrane with very low surface roughness

Mesh-reinforced cellulose acetate (CA)-based membranes were prepared for forward osmosis (FO) by immersion precipitation. Casting compositions such as CA percent and 1, 4-dioxane/acetone ratio and also preparation conditions such as evaporation time, coagulation bath and annealing temperatures were tested for membranes’ performance. The results were compared with commercially CTA membranes. The best membrane (17.9% polymer and 1, 4-dioxane/acetone ratio of 1.89) showed water flux of 9.3 L/m²h (LMH) and RSF of 0.536 mol NaCl/m²h. Moreover, the membrane structure was reinforced by a polyester mesh, which created micro pores in the back of the membrane. This caused higher water flux and RSF compared to membranes without mesh. FO membrane prepared under best conditions, had a smoother surface than commercial ones. This feature enhances the fouling properties of the membrane, which can be appropriate for wastewater treatment applications.     

Cellulose/casein blend membranes from NaOH/urea solution

Cellulose membranes and cellulose/casein blend membranes were successfully prepared from a new solvent system (6 wt % NaOH/4 wt % urea aqueous solution) by coagulation with a sulfuric acid aqueous solution. The structures and properties of the membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), wide-angle X-ray diffraction, differential scanning calorimetry, and a tensile test. The experimental results showed that the suitable coagulation condition was 5 wt % H₂SO₄ for 5 min. When the casein content of the mixture was less than 15 wt %, the blend membranes were miscible because of the interactions between the hydroxyl groups of cellulose and the peptide bonds of casein. The blend membranes with 10 wt % casein had good miscibility, higher crystallinity, and the highest mechanical properties and thermal stability. In this case, the tensile strength and breaking elongation of the blend membranes were 109 MPa and 16%, respectively, and its pore size, obtained by SEM, was 290 nm, which suggests that the blend membranes provide a potential application for the field of separation technology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3260–3267, 2001     

纤维素/NMMO溶液及其薄膜的制备与性能研究

以水质量分数为13.3%的N-甲基吗啉-N-氧化物(NMMO)为溶剂溶解棉浆粕,制备质量分数为5%～11%的纤维素/NMMO溶液。将所得溶液制备纤维素薄膜,考察了纤维素/NMMO溶液的稳定性,研究了凝固浴温度和组成对纤维素薄膜的成膜性、断面形态及力学性能的影响。结果表明:纤维素/NMMO溶液随着浓度增大,其粘度先增大后减小,再急剧上升;纤维素/NMMO溶液在玻璃介质中稳定性较好,微量Cu~(2+),Fe~(3+)等杂质存在时,其稳定性显著下降;纤维素薄膜随凝固浴温度升高,其透明性、拉伸强度和断裂伸长率均下降;相对于水,含有乙醇和NMMO的凝固浴能减缓双扩散的速度,使纤维素薄膜的拉伸强度略有提高,断裂伸长率出现不同程度下降。