Structure-performance-fouling studies of polysulfone microfiltration hollow fibre membranes

Hollow fibre microfiltration membranes were prepared by solution spinning process using polymer dope containing different amounts of polysulfone (PS), polyvinylpyrollidone (PVP) and ${\bf \textit{N}}$ , ${\bf \textit{N}}$ -dimethylformamide (DMF). Spinning dope having PS: PVP: DMF (w/w) of 15: 5: 80, 15: 7: 78 and 17: 8: 75 were used for spinning to obtain hollow fibres having different dimensions (outer and inner diameters) and pore characteristics. Relatively high water permeability was observed for hollow fibre membrane spun from 15?wt.?% solution than 17?wt.?% PS solution having the same PVP/PS ratio of 0·47. Decrease of the PVP/PS ratio to 0·33 in the dope solution of 15?wt.?% PS solution produced hollow fibre membrane with lower flux. By changing the spinning parameters, fibre with different dimensions were obtained without a significant change in microstructural morphology. The flux decline due to fouling for the permeation of PEO/BSA solution was maximum for the hollow fibre membrane obtained from 15?wt.?% PS solution while a steady flux with slight fouling was observed for the hollow fibre membrane obtained from 17?wt.?% PS solution, when the PVP/PS ratio was 0·47.     

NaA分子筛改性聚砜超滤膜的通量及截留性能

利用溶液相转化法,在铸膜液中加入分子筛NaA和PEG来协同提高聚砜超滤膜的水通量和截留率,研究了分子筛的含量对聚砜超滤膜的形貌结构,表面粗糙度,水通量,蛋白质截留率和亲水性的影响。利用场发射扫描电镜、扫描探针原子力显微镜、膜评价仪和接触角仪分别对该膜的形貌、水通量、蛋白质截留率和亲水性进行表征。结果表明分子筛含量从0g增加到3.0g,聚砜超滤膜的水通量从140L/(m2·h)提高到500L/(m2·h),对胃蛋白酶的截留率从78.8%提高到92.7%,对牛血清蛋白的截留率从97.6%增加到99.0%以上。分子筛NaA可以协同提高聚砜超滤膜的水通量和蛋白质截留率。     

Sulfonated polyethersulfone-based membranes for metal ion removal via a hybrid process

Membranes are being increasingly used as an economic alternative for wastewater treatment compared to conventional methods. Ultrafiltration membranes are widely used in metal ions’ rejection. Sulfonated Polyethersulfone (SPES)/polysulfone (PSf) blend flat sheet membranes are prepared using polar solvent N-methyl-2-pyrrolidone (NMP) by the dry–wet phase inversion technique. Polyethylene glycol (PEG-200) is used as a non-solvent additive in the casting solution. The effect of PSf/SPES blend ratio on the morphology, hydrophilicity, water content, porosity, hydraulic resistance, pure water flux, compaction, and molecular weight cut-off (MWCO) of the prepared membranes was studied and found to be improved significantly by the incorporation of SPES in the dope solution. Scanning electron microscopy (SEM) studies revealed that the membranes formed had an asymmetric structure with a thin skin layer and porous sublayer. The prepared membranes were used for rejection of Cu(II) and Zn(II) which are complexed with water-soluble chelating polymer polyethyleneimine. The results show that the order of rejection is Cu(II) ion > Zn(II) ion. Thus, it is worth mentioning that the PSf/SPES blend ultrafiltration membranes prepared in this study would offer immense potential in removal of toxic metal ion from industrial effluents.     

Synthesis of sulfated Y-doped zirconia particles and effect on properties of polysulfone membranes for treatment of wastewater containing oil

Polysulfone (PSF) membranes are broadly applied in many fields owing to good physicochemical stability, resistance to oxidation and chlorine. But when treated with wastewater containing oil, PSF membranes are easily contaminated due to their hydrophilicity, causing declining flux and lifespan of the membranes thereby limiting their large scale applications. In order to enhance the hydrophilic and anti-fouling capability of PSF membranes for treating wastewater containing oil, sulfated Y-doped zirconia particles (SO₄²⁻/ZrO₂-Y₂O₃ or SZY particles) were firstly synthesized and then doped into polysulfone to fabricate a novel hybrid membrane (SZY/PSF). The optimum preparation conditions of SZY particles were studied and determined. SZY particles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), specific surface area and transmission electron microscopy (TEM). Wastewater containing oil (80 mg/L) was used to investigate the separation properties of SZY/PSF membranes. The results show that the oil concentration in the permeation is 0.67 mg/L, which meets the recycle standard of the Chinese oil-field (SY/T 5329-94, oil concentration <10 mg/L). It is concluded that doping SZY particles into polysulfone can reasonably resist membrane fouling and SZY/PSF membranes can be considered feasible in treating wastewater containing oil.     

高通量抗污染碳量子点/聚砜纳米复合分离膜的制备

先以4-氨基水杨酸(ASA)为原料发生水热反应合成碳量子点(CDs),随后将其共混分散在铸膜液中用非溶剂诱导相分离法制备了PSF/CDs纳米复合膜。透射电子显微镜(TEM)观测和傅里叶变换红外光谱(FTIR)证实,CDs具有小尺寸和大量亲水基团的特点。使用水接触角分析(WCA)、扫描探针显微镜(SPM)和扫描电子显微镜(SEM)对分离膜进行了表征,发现纳米复合膜具有比原始膜更好的亲水性和更多的孔洞,从而使分离膜具有更高的通量和抗污染性能。PSF/CDs膜的通量回复率(FRR)超过90%,总污染率(Rt)低于60%,且可逆型污染为主要污染源。CDs含量(质量分数)为2%的复合膜整体效果最佳。具有更强抗污染能力的纳米复合膜,其水通量甚至为纯PSF膜的3倍。     

外加磁场下聚砜-Fe_3O_4复合超滤膜的孔径变化

以无磁性聚砜超滤膜为对照,采用液-液界面法,以水-正丁醇体系为对象,对不同磁场强度下,聚砜-Fe3O4磁性复合超滤膜的孔径变化规律进行了研究。结果表明,在不同磁场下,2张空白聚砜膜的孔径无显著变化,3张聚砜-Fe3O4复合膜的孔径变化显著且趋势相同,即0T~0.4 T时,平均孔径随场强增大而增大,0.4T~1.2T时,平均孔径随场强增大而减小。纯水通量实验结果显示,不同磁场对膜通量影响的变化趋势与所测孔径变化相吻合。     

Blood compatibility and filtration characteristics of a newly developed polyester polymer alloy membrane

Background: Many synthetic polymeric membranes have been widely used for blood purification therapies for removing larger solutes and for better blood compatibility. Methods: Five different filters with polyester polymer alloy (PEPA) membrane (Nikkiso) that included polyvinylpyrrolidone (PVP), that is, standard‐pore‐size FLX (PEPA with PVP(–)), standard‐pore‐size FDX (PEPA with PVP(+)), new FDX (PEPA with PVP(++)), larger‐pore‐size FDY (PEPA with PVP(+)), and new FDY (PEPA with PVP(++)), were evaluated in terms of in vivo blood compatibility and aqueous in vitro sieving coefficient (s.c.) for albumin. Results: FDY showed excellent small changes in C3a concentration during the treatment right after switching from polysulfone membrane, leaving no significant changes in other blood‐compatible indices. New FDY, in contrast, showed less biocompatible characteristics in terms of C3a, which may be caused by increased use of PVP. FLX (no PVP) showed the highest s.c. for albumin. With a hydrophilic agent (PVP), the s.c. was greatly reduced in FDX. By enlarging the pore diameter in FDY, the s.c. increased in accordance with the enlargement. Generally speaking, polysulfone filters with PVP(+++) reach the peak s.c. value approximately 10 min after starting the experiment. The s.c. of the PEPA membrane with no or small amount of PVP, which showed excellent blood compatibility, never showed peaks, whereas the peak s.c. values were found in new PEPA with increased amount of PVP that showed higher C3a changes. Conclusions: The separation characteristics of aqueous albumin may be related to its blood compatibility.     

Sorption, diffusion, and pervaporation characteristics of dimethylformamide/water mixtures using sodium alginate/polyvinyl pyrrolidone blend membranes

Separation of aqueous dimethylformamide (DMF) solutions in the concentration range of 0-100 wt% were studied using sodium alginate (NaAlg)/polyvinyl pyrrolidone (PVP) blend membranes. The NaAlg was blended in different ratios with PVP. Prepared membranes were crosslinked with CaCl₂ for testing in pervaporation (PV) separation of DMF/water mixtures. Effects of feed composition (0-100 wt%), operating temperature (30-50 °C), and membrane thickness were investigated. Best results were obtained at the conditions of 75/25 NaAlg/PVP blend ratio (w/w), 40 °C temperature, 20 wt% DMF concentration, and 70 μm membrane thickness. Blending of PVP with NaAlg increased permeation flux whereas it decreased the separation factor. NaAlg/PVP membranes gave separation factors of 5.5-27 for permeation flux of 0.96-1.81 kg/m²h depending on the operating temperature and the feed mixture composition. Arrhenius plot of permeation flux data versus reciprocal of temperature exhibited linear trends. Permeation activation energy of DMF and water in the PV was calculated as 6.76 and 1.88 kcal/mol, respectively, using an Arrhenius type relationship. Sorption-diffusion properties of the NaAlg/PVP membranes were also investigated at the operating temperature and the feed composition.     

Selective Permeation of Water through Angstrom-Channel Graphene Membranes for Bioethanol Concentration

Graphene-based laminate membranes have been theoretically predicted to selectively transport ethanol from ethanol–water solution while blocking water. Here, robust angstrom-channel graphene membranes (ACGMs) fabricated by intercalating carbon sheets derived from chitosan into thermally reduced graphene oxide (GO) sheets are reported. ACGMs with robust and continuous slit-shaped pores (an average pore size of 3.9 Å) are investigated for the dehydration of ethanol. Surprisingly, only water permeates through ACGMs in the presence of aqueous ethanol solution. For the water-ethanol mixture containing 90 wt% ethanol, water can selectively permeate through ACGMs with a water flux of 63.8 ± 3.2 kg m⁻² h⁻¹ at 20 °C and 389.1 ± 19.4 kg m⁻² h⁻¹ at 60 °C, which are over two orders of magnitude higher than those of conventional pervaporation membranes. This means that ACGMs can effectively operate at room temperature. Moreover, the ethanol can be fast concentrated to high purity (up to 99.9 wt%). Therefore, ACGMs are very promising for production of bioethanol with high efficiency, thus improving its process sustainability.     

聚乙烯吡咯烷酮含量对聚偏氟乙烯/聚醚砜共混膜性能和结构的影响

采用二甲基乙酰胺为溶剂,聚乙烯吡咯烷酮(PVP K90)为致孔性添加荆,研究了PVP的浓度对聚偏氟乙烯/聚醚砜(PVDF/PES)共混膜的收缩率、纯水通量、牛血清蛋白(BSA)截留率和膜结构的影响.在PVP含量为5%时,共混膜的收缩率最低,水通量取得极大值,截留率有一极小值.     

Novel carbon fiber/epoxy composite toughened by electrospun polysulfone nanofibers

Novel carbon fiber/epoxy composite toughened by electrospun polysulfone (PSF) nanofibers was prepared to enhance fracture toughness of the composite, and compared the morphology and toughness to those of composite toughened by PSF films prepared by solvent method. Polysulfone nanofibers with the average diameter of 230 nm were directly electrospun onto carbon fiber/epoxy prepregs to toughen the composite. SEM observations of the polysulfone nanofibers toughened composite revealed that polysulfone spheres with uneven sizes presented uniform dispersion through interleaves of the composite, which was different from those of composite toughened by PSF films. Mode I fracture toughness (G_IC) of the nanofibers toughened composite was 0.869 kJ/m² for 5.0 wt.% polysulfone nanofibers content, which was 140% and 280% higher than those of PSF films toughened and untoughened composite due to the uniform distribution of polysulfone spheres.     

多元合金超滤膜研制

主要研究了聚醚砜（PES）,聚砜（PSF）和磺化聚砜（SPSF）共混所形所的多元合金超滤膜的性能和膜的孔径分布特性,初步探讨了多元合金超滤膜的成孔机理,并对共混体系的组成及相容性与合金超滤膜性能问题的关系作了详细讨论,研究结果且明,共混可明显改善超滤膜的孔径分布和膜的孔结构,为制备高性能越滤膜提供一种有效途径。     

Blood Compatibility and Filtration: Characteristics of Newly Developed Polyester Polymer Alloy Membrane

Many synthetic polymeric membranes have been widely used for blood purification therapies. Among them polyester polymer alloy (PEPA) membrane shows unique blood compatibility and filtration characteristics. Objective: To evaluate blood compatibility and filtration characteristics of 3 different PEPA membranes, including FLX (PEPA only), FDX (PEPA with polyvinylpyrrolidone, (PVP) as a hydrophilic agent), and FDY (PEPA with PVP) that has larger pore diameter. Methods: Ultrafilters with 3 PEPA membranes (FLX, FDX, FDY, Nikkiso, Tokyo) were compared with those with polysulfone (PS; NK‐PS, Nikkiso, Tokyo) for blood compatibility in vivo. Also, ultrafilters with PEPA, PS, and cellulose triacetate (CTA; FB‐110GA, Nipro, Osaka) membranes were also investigated for filtration characteristics of albumin in aqueous in vitro. Results: FDY, the latest version of the three PEPA, showed excellent small changes in C5a concentration during the treatment right after switching from PS membrane, leaving no significant changes in other biocompatible indices. First 60 min of the time course of s.c. for albumin were shown below taken under aqueous low albumin concentration, i.e., 2.42 × 10^?3 kg/dm³. The time‐dependent patterns were totally different from each other in 5 filters. Generally speaking, PS takes a peak value 20–40 min after starting the experiment, depending on the flow conditions. Since PEPA is a hydrophobic material, it showed high s.c. for albumin in FLX (PEPA with no PVP) and never reached plateau. With a hydrophilic agent (PVP), the s.c. greatly reduced in FDX and showed little time‐dependent change. By enlarging the pore diameter in FDY, the s.c. increased in accordance with the enlargement. Conclusion: Newly developed PEPA with PVP has excellent blood compatibility and has unique separation characteristics for albumin.     

PSF/SPSF合金膜的相容性对膜性能的影响

聚砜(PSF)／磺化聚砜(SPSF)合金膜是采用液相共混及相转换法制成的．本文研讨了PSF/SPSF的相容性与其合金膜性能之间的相关性．根据在不同组成条件下混合熵值的计算结果判断，PSF／SPSF合金是一部分相容的体系．实验结果表明，在本实验范围内随着SPSF含量的增加，PSF／SPSF体系相容性降低，从而引起合金膜的纯水量升高，截留率下降．溶剂的种类及混合溶剂的比例也影响PSF/SPSF的相容性，从而影响膜的性能．在NMP-DMF混合溶剂中，随着DMF含量的增大，PSF/SPSF合金体系的相容性变差，其结果造成膜的通量升高，同时截留率下降．     

添加剂对聚丙烯腈膜结构和性能的影响

采用相转化法制备聚丙烯腈膜,分别以高分子聚乙烯吡咯烷酮(PVP-K30和PVP-K90)、聚乙二醇(PEG-2000和PEG-6000)和有机小分子乙二醇、无机盐氯化锂(LiCl)等六种物质作为制备聚丙烯腈膜的添加剂,含量均为3%(质量分数)。并对聚丙烯腈膜的表面和断面结构、水通量、孔隙率、水接触角及对牛血清蛋白(BSA)的截留率等进行了测试及表征。结果表明:以PEG-2000作为添加剂制得的膜的微孔较多,孔径较大,断面为指状结构,具有最大的水通量和孔隙率,达到436L/(m~2·h)和86%;有机小分子乙二醇作为添加剂制得的膜的水通量较低,但对BSA的截留率最高,为93%;聚乙烯吡咯烷酮(PVP)和聚乙二醇(PEG)制得的膜的水接触角较低,最小达到68°,亲水性较好。     

Morphology evolution of polysulfone nanofibrous membranes toughened epoxy resin during reaction-induced phase separation

The phase separation process and morphology evolution of 5 wt% polysulfone (PSF) nanofibrous membranes toughened epoxy resin at different temperatures were investigated by synchrotron radiation small angel X-ray scattering (SR-SAXS), phase contrast microscopy (PCM) and scanning electron microscopy (SEM). The onset time of phase separation obtained by different methods was basically identical. As the curing proceeded at constant temperature, the scattering peak corresponding to the maximum scattering intensity shifted to a smaller scattering vector (q_m), and the average diameters of PSF spheres increased, which showed a phase separation pattern of nucleation and growth mechanism. PSF spheres exhibited random alignment in “sea-island” morphology, which was attributed to the in situ phase separation of PSF nanofibers. Also, the effects of phase separation kinetics on the phase morphology and fracture toughness of nanofibrous membranes toughened epoxy resin were investigated. Results showed that the phase separation process was faster than the curing reaction process, which implied that the diffusion coefficient of PSF in epoxy resin increased with increasing the curing temperature, resulting in the increase of PSF sphere size that in turn improved the fracture toughness at higher temperature.     

Preparation and characterization of poly (methyl methacrylate) and sulfonated poly (ether ether ketone) blend ultrafiltration membranes for protein separation applications

Poly (methyl methacrylate) (PMMA) and poly (methyl methacrylate)/sulfonated poly (ether ether ketone) (SPEEK) blend membranes were prepared by phase inversion technique in various composition using N,N'-dimethylformamide as solvent. The prepared membranes were characterized in terms of pure water flux, water content, porosity and thermal stability. The addition of SPEEK to the casting solution resulted in membranes with high pure water flux, water content, porosity and slightly low thermal stability. The cross sectional views of the blend membranes under electron microscope confirm the porosity and water flux results. The effect of the addition of SPEEK into the PMMA matrix on the extent of bovine serum albumin (BSA) separation was studied. It was found that the permeate flux increased significantly while the rejection of BSA from aqueous solution reduced moderately during ultrafiltration (UF) process. The effect was attributed to the increase in porosity and charge of the membrane due to the addition of SPEEK into the PMMA blend solution.     

聚乙烯吡咯烷酮/聚(乙烯-乙烯醇)共混膜的制备及其油水分离性能

将聚乙烯吡咯烷酮(PVP)与聚(乙烯-乙烯醇)(EVAL)共混,采用浸没沉淀法制备了PVP/EVAL共混膜,并用于油水乳液分离过程。通过全反射红外光谱、扫描电子显微镜、拉伸试验、接触角测试等对膜的组成、结构形态、机械性能、亲水性进行了表征,并研究了PVP添加量对共混膜油水分离性能的影响。结果表明:添加PVP能较显著地改变EVAL膜的结构,且共混膜的机械强度和亲水性得到明显改善,当PVP添加量为10 wt%(PVP在铸膜液中的质量分数)时,其拉伸强度和断裂伸长率分别为纯EVAL膜的1.88倍和1.34倍。当PVP添加量为4 wt%时,油水分离稳定通量为纯EVAL膜的1.81倍,截留率为92.2%,比纯EVAL膜略高。PVP添加量为10 wt%的PVP/EVAL共混膜清洗后通量恢复率由纯EVAL膜的51%增至77.98%。     

磺化聚醚醚酮与聚砜共混膜导电与传质特性研究

以磺化聚醚醚酮(SPEEK)和聚砜(PSF)为原材料，N，N-二甲基甲酰胺(DMF)为溶剂，采用溶液共混方法，制备了一系列不同组成的SPEEK与PSF共混膜．研究发现，随PSF含量的增加共混膜的相分离行为加剧，电导率有一定下降，但阻醇性能得到提高．     

Characterization and reactivity of chromia nanoparticles prepared by urea forced hydrolysis

Chromia (Cr₂O₃) nanoparticles were prepared by urea forced hydrolysis in the presence of chromium (III) nitrate using NaCl as a precipitating agent. The size, distribution, and purity of the particles were evaluated. The necessity of polyvinylpyrrolidone (PVP) as a surfactant to prevent aggregation was also investigated. In the presence of PVP, non-aggregated spherical-like nanoparticles (3 ± 1 nm) were formed, whereas in the absence of PVP, spherical-like weakly agglomerated nanoparticles (85 ± 16 nm) comprised of 10 nm nanoparticle subunits were produced, creating a large surface area. The as-formed hydrated Cr₂O₃ nanoparticles were amorphous, although they could be easily converted into crystalline form by heating to 400 °C for 1 h, with minimal particle aggregation and size reduction. Attenuated total reflectance Fourier transform infrared spectroscopy indicated that preparation methods (surfactant and precipitating agent) influence surface reactivity of the nanoparticles to catechol.