PAC-UF处理含蛋白质类溶液过程中的膜污染研究

使用粉末活性炭(PAC)-超滤(UF)组合工艺处理牛血清白蛋白(BSA)溶液,研究了不同PAC投量下组合工艺的膜污染情况。结果表明,PAC本身对膜污染无明显贡献,PAC吸附BSA后使得膜通量急剧下降;PAC对改善BSA溶液通过超滤的膜通量和膜污染阻力均有一个最佳投加值;PAC在膜表面形成的滤饼层对膜通量改善作用明显;PAC滤饼层主要形成可逆污染,而水中BSA则是不可逆膜污染。     

接枝丙烯酸亲水化改性聚砜超滤膜及其在多肽分离中的应用

采用丙烯酸亲水化改性聚砜中空纤维超滤膜。以四氯化锡为催化剂,磷酸为催化助剂,通过检测接触角,优化了丙烯酸浓度与催化剂用量（摩尔比1:0.05）、反应温度（30ºC）和反应时间（60min）等改性条件。红外光谱检测表明羧基被成功地接枝于膜表面;扫描电镜分析说明表面改性未对膜面和膜骨架造成损坏。通过超滤不同浓度的牛血清白蛋白（BSA）溶液,证明改性膜（MM）比未改性膜（UMM）具有更好的抗蛋白吸附性能。将MM应用于酪蛋白酶解物活性多肽的分离制备时,优势体现于长期操作中较高的渗透通量与渗透液中更为合理的分子量分布两方面。     

共混高分子膜渗透蒸发分离乙醇水溶液

应用湿法离子交联技术，研制了聚砜酰胺共混聚丙烯酸复合膜，针对乙醇水溶液，测定了膜的分离系数和渗透通量。实验发现，这种共混膜对乙醇－水具有较高的分离选择性。     

低温水等离子体活化和表面接枝DMAE聚氯乙烯中空纤维膜研究

采用低温水等离子体技术,在三通道聚氯乙烯(PVC)膜表面接枝了甲基丙烯氧基苄基二甲基氯化铵(DMAE)单体,增强了膜亲水和抗菌性能。通过红外分析,表明DMAE成功接枝到了PVC膜上,水通量提高两倍,PVC-ir-H₂O膜(通过水等离子体处理的膜)对牛血清蛋白(BSA)的吸附能力下降67%,对BSA溶液的通量从7.7提高至40 kg·m^-2·h^-1,并且对BSA的截留能力不变。通过静态及动态抗菌实验,接枝后的PVC膜(PVCg-PMAE膜)抗菌率达到100%,膜组件运行中的抗菌率也达到82%以上。在保证细菌截留率100%的同时,其渗透通量提高三倍。该膜表面修饰工程技术能实现膜表面的均一化改性,且绿色环保、操作简便、成本低,改性膜在饮用水处理领域,尤其是家用净水器中展现了很好的应用前景。     

聚醚共聚酰胺(PEBA)膜的溶胀和渗透汽化行为研究

用涂布法制备出PEBA均质膜,分别测试了膜在纯醋酸正丁酯、水以及醋酸正丁酯稀水溶液中的溶胀率,并考察了浸泡时间、温度和溶液浓度对溶胀率的影响;结果表明:PEBA膜在水中溶胀很小,对醋酸正丁酯具有优先吸附能力;溶胀率随浸泡时间的延长、浸泡液浓度和温度的升高而逐渐上升。渗透汽化实验表明膜对醋酸正丁酯的良好选择性,膜的渗透通量和分离因子随着浓度的增加而增加,渗透通量随着温度的升高而增加,但分离因子随温度的升高而减小;当原料液浓度为0.6%(wt)时,醋酸正丁酯的渗透通量为143.9g·m-2·h-1,分离因子达到236.9。     

聚砜超滤膜与低分子有机物交互作用的研究

选取聚砜平板超滤膜,采用间歇错流循环方式对离子型表面活性剂与低分子有机物的混合料液进行分离,考察了表面活性剂的浓度、操作压力等因素对超滤过程的影响,研究料液与膜之间的交互作用。结果表明,有机物与表面活性剂的混合料液的通量均高于自来水的通量;表面活性剂的浓度低于临界胶束浓度(CMC)时,膜通量随其浓度的增加而增加,而高于CMC时通量略有下降;改变操作压力,混合溶液的通量随压力的降低而减小,其中苯酚的通量变化不大,但均保持较高的渗透通量。     

聚乙烯醇膜的研制及乙醇水溶液的渗透蒸发（PV）分离

选择以聚乙烯醇(PVA)作膜材料,制成具有一定通量及分离效果的聚乙烯醇均质膜及聚乙烯醇/聚砜复合膜。讨论了膜的抗水性及抗化学腐蚀性。用透射电镜及扫描电镜进行了结构测定,并研究了这两种膜在分离95%(重量浓度)乙醇水溶液时的性能以及温度、交联度对膜性能的影响。实验发现聚乙烯醇均质膜具有较高的分离系数;聚乙烯醇/聚砜复合膜在基本维持均质膜分离性能的前提下,通量有较大提高。还发现经Cr~(3 )的饱和溶液处理后再进一步交联的膜,交联度及稳定性都有提高,分离系数略有下降。     

固液两相流对管式膜超滤过程强化的研究

采用PVDF管式膜对牛血清蛋白溶液进行错流超滤实验,加入活性炭、陶瓷、PVC等固体粉末形成固液两相流,考察在固液两相流下粉末种类、跨膜压差、膜面流速、料液蛋白浓度及粉末投加量等参数对管式膜超滤过程的影响。实验结果表明,陶瓷粉末因其硬度大,易造成膜面磨损,不适宜作为固相介质。活性炭粉末硬度适宜、廉价易得且较PVC粉末强化效果明显,当牛血清蛋白浓度为100 mg/L时,活性炭粉末(饱和)投加量为2.5 g/L左右效果最佳;跨膜压差越大、料液蛋白浓度越高,固液两相流对超滤过程的强化效果越明显,0.5 MPa时渗透通量可提高84%;增大膜面流速利于提高渗透通量。可见,引入固液两相流能有效减缓浓差极化和膜污染,对管式膜超滤过程强化效果明显,有利于提高膜过滤效率。     

正渗透去除微塑料效能及其响应面法优化

试验选取PET塑料颗粒作为去除目标物，NaCl溶液为汲取液，分别考察正渗透膜通量变化及对PET颗粒的去除影响因素分析。结果表明：增大汲取液浓度、运行温度、膜面流速和PET粒径均能显著提高膜通量，且其总膜比通量也较大，但与膜通量衰减存在一定交互作用；试验周期内，在汲取液中未检测到PET颗粒，去除率可达100%。去除率分别由膜截留率及装置系统吸附率贡献，两者占比在各去除影响因素分析中有所变化，其中汲取液浓度、膜面流速和粒径对吸附率去除贡献比影响较大，而温度对其影响不显著，且相关性不强；最后用响应面法优化汲取液浓度、膜面流速和温度对总膜比通量的影响。回归模型分析表明三种影响因素影响程度为：1）在低膜面流速的条件下汲取液浓度>膜面流速>温度；2）在高膜面流速的条件下汲取液浓度>温度>膜面流速。优化方案模型的模拟预测值与实验测试值基本吻合。     

膜形态、膜污染和浓差极化对流动电位的影响

引　言膜与水溶液接触后 ,由于自身所具有的固定荷电基团的静电吸附或膜表面ｖａｎｄｅｒＷａａｌｓ力对溶液中某些反离子的不等量吸附作用 ,使被吸附的离子紧贴在固体表面 ,形成一个固定的吸附层 ,叫Ｓｔｅｒｎ层 ,同时从Ｓｔｅｒｎ层到液体内部又形成了扩散层 ,带电膜的表面与电解质溶液相对移动时在Ｓｔｅｒｎ层和扩散层之间形成一个剪切面 ,剪切面与溶液体相的电位差即 ζ电位 ,其大小与膜表面吸附离子的性质与数量有关 ,反映出膜表面荷电性能 .多年来 ,许多关于膜荷电性能的研究工作表明膜表面的荷电会影响膜的通量和对溶液中带电微粒…     

Comparative Study of Enantioseparation of Racemic Tryptophan by Ultrafiltration Using BSA-Immobilized and BSA-Interpenetrating Network Polysulfone Membranes

Effectiveness of Bovine Serum Albumin (BSA) as chiral recognizing protein in enantiomers separation by ultrafiltration technique was studied by immobilizing BSA on the membrane and incorporating BSA as semi-interpenetrating network in the membrane matrix. Separation of racemic tryptophan solution was performed in closed loop cross flow ultrafiltration using BSA immobilized polysulfone membrane and polysulfone membrane having BSA semi-IPN network. The volumetric flux (J_v), the solute flux (J_s), the separation factor (α), and the enantiomeric excess (%ee) of two types of membranes at different trans-membrane pressures and permeation times were determined. BSA semi-IPN membrane exhibits higher volumetric as well as solute fluxes compared to BSA immobilized membrane. Separation factor (α) to the order of 1.89 was achieved with BSA immobilized membrane after 8 h of ultrafiltration and in the same duration BSA-IPN membrane exhibited separation factor (α) to the order of 1.62. BSA immobilized membrane exhibits higher enantiomeric excess (30.8%) compared to BSA semi-IPN membrane (23.8%) after 8 hrs. BSA molecules available on membrane as immobilized or as semi-IPN under go complexion with tryptophan enantiomers differently. BSA immobilized membrane performed better separation and enantiomeric purity; however, the solute flux of the membrane decreases.     

亲水化改性PVDF超滤膜的抗污染特性研究

以不同通量的自制亲水化纳米SiO2改性PVDF超滤膜(PS)和聚乙烯醇改性PVDF超滤膜(PA),对城市污水二级出水(EfOM)和牛血清蛋白(BSA)水溶液进行了过滤试验,通过对比未添加改性剂的PVDF超滤膜,考察通量衰减率、膜污染阻力构成、通量恢复率等指标,分析水质与膜材料间的相互关系对超滤膜抗污染能力的影响.结果表明,在BSA料液中,3种通量下,低通量的膜抗污染能力好于高通量膜.20 min内PA膜表现出最低的膜通量衰减,而P膜在过滤初期通量就急剧下降.在EfOM料液中,各通量下,P膜通量衰减严重且产生了不可逆的堵孔阻力,亲水化改性后膜通量衰减率降低,稳态通量高,膜污染阻力主要来自于浓差极化和滤饼层阻力,其中PS膜通量下降率最低,而PA膜清洗后通量易恢复.     

Concentration of gelatin solution with polyethersulfone ultrafiltration membranes

In this work, polyethersulfone (PES) flat sheet ultrafiltration (UF) membranes were prepared by immersion precipitation phase inversion process with polyvinylpyrrolidone (PVP 30K) and acetone as additives. The best preparation condition for PES membranes with high water flux and rejection (to BSA) was decided. It was found that the optimal composition of the polymer casting solution was: 16 wt% (PES), 2 wt% (PVP 30K), and 1 wt% (acetone). Pure water flux of the membrane prepared at this condition reached to 373 L/m² h at 0.1 MPa, and the rejection to BSA was 91%. Compared with other reports, the rejection was slightly low but the flux of the PES membrane was high. When the membrane was used to concentrate gelatin solutions, the rejection value was over 75%. It was found that increasing the feed temperature and transmembrane pressure enhanced the permeation flux, but the rejection decreased slightly. However, increasing the cross-flow velocity of the feed solution simultaneously increased both the permeation flux and the rejection.     

Effects of coagulation bath temperature and polyvinylpyrrolidone content on flat sheet asymmetric polyethersulfone membranes

In this study, effects of coagulation bath temperature (CBT) and polyvinylpyrrolidone (PVP K15) concentration as a pore former hydrophilic additive on morphology and performance of asymmetric polyethersulfone (PES) membranes were investigated. The membranes were prepared from a PES/ethanol/NMP system via phase inversion induced by immersion precipitation in a water coagulation bath. The morphology of prepared membranes was studied by scanning electron microscopy (SEM), contact angle measurements, and mechanical property measurements. Permeation performance of the prepared membranes was studied by separation experiments using pure water and bovine serum albumin (BSA) solution as feed. The obtained results indicate that addition of PVP in the casting solution enhances pure water permeation flux and BSA solution permeation flux while reducing protein rejection. Increasing CBT results in macrovoid formation in the membrane structure and increases the membrane permeability and decreases the protein rejection. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

聚丙烯腈超滤膜的制备

为了得到高性能的超滤膜,采用相转化法,以聚丙烯腈(PAN)为原料,N-甲基-吡咯烷酮(NMP)为溶剂,制备了聚丙烯腈超滤膜.采用纯水通量以及膜对牛血清蛋白(BSA)的截留率作为评价标准,并使用扫描电镜对膜结构进行表征.研究了聚合物质量分数、添加剂种类、凝胶浴温度、凝胶浴种类对膜性能的影响.研究发现:在一定范围内提高聚合...     

平板式超声对污染聚偏氟乙烯中空纤维超滤膜清洗

Polyvinylidenefluoride （PVDF） hollow fiber ultrafiltration membrane is frequently employed in water treatment. However, the fouling of ultrafiltration membranes affects the economic effectiveness of such process significantly. The ultrasound generated by flat plate transducer （UFPT） was used to clean the polluted PVDF ultrafiltration membrane with 2 g·L^-1 of citric acid aqueous solution in our study. The effects of UFPT intensity on the membrane surface were studied. The new membrane was easy to be polluted by the saturated CaCl2 solution. A synergistic effect of UFPT and 2 g·L^-1 citric acid aqueous solution could remove the foul of the membrane, and its flux could be recovered about 81%. The flux recovery of old membrane polluted was increased to 73.2% after 7 h soaking in citric acid aqueous solution, but its flux recovery without soaking was only increased to 56.2%.     

EAA及致孔剂PEG400改性PVDF膜的结构及其渗透性能

为了调控聚偏氟乙烯(PVDF)膜的孔状结构和性能,以EAA(聚乙烯丙烯酸)作为添加剂,以PEG400作为致孔剂,通过浸入沉淀相转换法制备了一系列PVDF/EAA复合超滤膜,通过扫描电镜、红外、水接触角、黏度表征、孔隙率、纯水通量、牛血清蛋白(BSA)截留率、通量恢复率和污染率等测试手段,研究了不同的EAA含量和不同的致孔剂PEG400含量对复合膜性能的影响。结果表明,EAA的添加改善了膜表面的亲水性,致孔剂PEG400的加入提高了铸膜液和凝固浴之间的亲和性,加快了成膜速度,从而在膜表面形成更多的孔洞,其中E-3膜的纯水通量和BSA截留率分别达到了271.57 L.m_?2^.h_?1^和64.83%,相对于纯PVDF膜分别提高了约486.29%和116.10%;通量恢复率和总污染率分别为75.97%和46.51%,相对于纯PVDF膜分别提升了19.37%和降低了26.92%。而P-3膜的孔隙率为53.33%,平均孔径为4.55 nm,相对于未加致孔剂的P-0膜的孔隙率和平均孔径分别提高了约33.33%和88.02%;因此,本研究中提到EAA作为添加剂,及 PEG400作为致孔剂的方法可以显著改善PVDF膜结构和渗透性能。     

Perfluorosulfonic acid—Tetraethoxysilane/polyacrylonitrile (PFSA‐TEOS/PAN) hollow fiber composite membranes prepared for pervaporation dehydration of ethyl acetate–water solutions

Preparation of organic‐inorganic composite membranes and their pervaporation (PV) permeation and separation characteristics for the aqueous solution of ethyl acetate were described. Polyacrylonitrile (PAN) hollow fiber ultrafiltration membrane as support membrane, the mixtures of perfluorosulfonic acid (PFSA) and tetraethoxysilane (TEOS) by the sol‐gel reaction as the coating solution, the PFSA‐TEOS/PAN hollow fiber composite membranes by the different annealing conditions were prepared. The swelling of PFSA in ethyl acetate aqueous solutions was inhibited with addition of TEOS. The PFSA‐TEOS/PAN composite membranes containing up to 30 wt % TEOS in coating solution exhibited high selectivity towards water, then the selectivity decreased and permeation flux increased with increasing the TEOS concentration more than 30 wt %. When the PFSA‐TEOS/PAN composite membranes were annealed, the separation factor increased with increasing annealing temperature and time. Higher annealing temperature and longer annealing time promoted the crosslinking reaction between PFSA and TEOS in PFSA‐TEOS/PAN composite membranes, leading to the enhanced selectivity towards water. For the PFSA/PAN and PFSA‐TEOS/PAN composite membrane with 5 and 30 wt % TEOS annealed at 90°C for 12 h, their PV performance of aqueous solution 98 wt % ethyl acetate were as follows: the separation factors were 30.8, 254 and 496, while their permeation flux were 1430, 513 and 205 g/m² h at 40°C, respectively. In addition, the PV performance of PFSA‐TEOS/PAN composite membranes was investigated at different feed solution temperature and concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

PAN ultrafiltration membranes grafted with natural amino acids for improving antifouling property

In this report, antifouling polyacrylonitrile (PAN) ultrafiltration membranes were prepared from blends of PAN/polyglycidyl methacrylate (PGMA) via phase inversion method followed by the grafting of natural amino acids through epoxy ring-opening reaction. The grafted PAN membranes possessed highly stable hydrophilic surfaces as a result of the grafting of amino acids, which was adequately demonstrated in attenuated total reflectance–Fourier transform infrared spectroscopy (ATR/FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results of tensile strength and scanning electron microscopy (SEM) images further proved that the surface modification had little effect on their mechanical properties, surface, and cross-sectional morphologies. Meanwhile, remarkable resistance against bovine serum albumin (BSA) and lysozyme (Lyz) fouling was observed for the neutral amino acid-based PAN membranes due to the formation of zwitterionic hydration layer on the membrane surface, while PAN membranes grafted with charged amino acids were able to prohibit the approach of like charged proteins with reduced deposition and provide the driving force for oppositely charged protein adsorption. Furthermore, the ultrafiltration and antifouling performance of PAN membranes were investigated by BSA filtration experiments. Compared with the pristine PAN membrane, all the modified PAN membranes exhibited higher pure water flux, better flux recovery ratio, lower rejection, less total permeation resistance, and preferable stability, having potential applications in protein separation and purification.     

Permeation behavior of dextrans by charged ultrafiltration membranes of polyacrylonitrile photografted with ionic monomers

Charged copolymers, polyacrylonitrile, having grafts of quaternized poly(N,N-dimethylaminoethylmethacrylate) and poly(sodium p-styrenesulfonate), were synthesized by photograft-polymerization. The charged ultrafiltration membranes, which had heterogeneous porous structures, were prepared by casting graft polymer solution containing poly(vinyl alcohol) into water. The permeation of nonionic dextran and anionic dextransulfate through the charged membranes was studied by ultrafiltration in aqueous solution. The molecular weight cutoff characteristics of the charged membrances were obtained using dextrans of various molecular sizes. The permeation behavior was discussed in terms of the charge effect of the graft polymers and electrostatic interaction between the polymers and the solute molecules.