聚季铵盐强化超滤处理铬(VI)

以聚季铵盐-22(PQ22)为络合剂,研究Cr(VI)的强化超滤行为,考察聚电解质/金属质量比、pH值及外加盐对PQ22-Cr(VI)络合体系截留系数和膜通量的影响,并研究了络合体系的浓缩、解络合和洗涤过程. 结果表明,当聚电解质/金属质量比为80及pH=9时,Cr(VI)截留系数大于0.9;外加Cl-, NO3-和SO42-使Cr(VI)截留系数降低,且SO42-比NO3-和Cl-的影响更大;控制聚电解质/金属质量比为80及pH=9,当浓缩因子为20时,Cr(VI)浓度从初始的5 mg/L浓缩至82.6 mg/L;对浓缩液解络合,控制Cl-浓度为0.15 mol/L,解络合率为71.1%,以Cl-溶液对解络合液进行洗涤,Cr(VI)洗脱率可达95.9%. 聚季铵盐-22可循环使用.     

共涂覆法改性聚醚砜膜络合超滤除锑应用研究

针对商业聚醚砜(PES)膜表面亲水性差,在络合超滤除锑过程中膜通量损失较大的问题。采用一步共涂覆改性法,通过在PES基膜表面形成聚多巴胺和二氧化硅纳米颗粒杂化涂层,得到高亲水性表面。对改性膜进行了表征和络合超滤实验。结果表明,优化改性条件为TEOS投加量0.6 g、时间9 h,此时制备的膜接触角仅为17.5°,亲水性能显著提高;超滤过程中膜通量有效提升,而且锑截留率可从改性前的75.2%提高至77.4%。改性膜在循环超滤实验中只经过清水冲洗即可恢复90%以上的初始膜通量,具有较好的运行稳定性。     

胶团强化超滤处理水中环境激素双酚A研究

采用聚巩超滤膜和再生纤维素超滤膜,以十六烷基氛化吡啶(CPC)为表面活性剂,进行了胶团强化超滤处理水中双酚A (BPA)的研究,考察了操作压力、不同材质和截留相对分子质量的超滤膜、CPC浓度、溶液pH、电解质、非离子表面活性剂烷基多糖苷(APG)复配等因素对工艺的影响.结果表明,截留相对分子质量(MWCO)为5x103的聚砜UF膜和阳离子表面活性剂CPC,MEUF处理水中的BPA,在操作压力为0.15 Mpa,CPC的浓度为5 mmol·L-1条件下,对BPA的截留率可达90%以上,BPA的截留率及渗透液中CPC浓度随pH的变化而变化,电解质的存在以及CPC与APG的复配可以提高BPA的截留率,降低透渗透液中CPC的浓度.     

聚电解质涂层/纳米纤维膜复合滤膜的制备

以静电纺丝法制备的PAN纳米纤维多孔膜为基膜,以层层自组装成膜技术制备的壳聚糖-海藻酸钠聚电解质涂层为表面选择性涂层,成功制备了聚电解质涂层/纳米纤维膜复合滤膜。用扫描电镜(SEM)对复合膜的微观形态进行表征。在操作压力为0.7MPa的条件下,分别过滤纯水以及质量浓度为1000mg/L的NaCl和500mg/L的MgSO4溶液,测试结果表明:盐离子截留率随聚电解质涂层层数的增加而增加,但同时复合膜的水通量随之明显降低。当聚电解质涂层层数为10时,水通量均在18L/m·2h左右,对MgSO4截留率为64.22%,对NaCl截留达到52.45%。     

地下水除铁除锰-超滤组合工艺的膜污染特性

针对含铁锰地下水采用直接超滤工艺、曝气-超滤工艺和曝气-砂滤-超滤工艺对比研究了除铁除锰效果和膜污染特性。研究结果表明,超滤膜可以有效截留三价铁,但对二价锰的截留效果不佳;曝气-砂滤-超滤组合工艺可以显著提高除铁除锰效果和工艺稳定性,超滤出水铁和锰含量达0.10 mg/L和0.02 mg/L。此外,SEM分析结果发现,预处理工艺对滤饼层形态有显著影响,直接超滤工艺和曝气-超滤工艺的滤饼层较松散,曝气-砂滤-超滤工艺形成的致密滤饼层是造成其运行后期跨膜压差快速增长的重要因素;EDS及XPS分析表明膜表面的滤饼层主要由三价铁颗粒组成,是造成膜污染和跨膜压差的主要成分。     

PH对荷电有机超滤膜处理金属离子溶液的影响

分别以NaCl、KCl、MgCl2、CaCl2和AlCl3溶液为背景电解质液,测定了聚砜中空纤维超率膜(截留分子量为6k)的流动电位、膜渗透性、离子截留率及pH值差(pH渗透液-PH截留液),并考察pH值对这些参数的影响;在此基础上,研究不同pH环境中离子混合溶液的超滤行为,并与单一溶液进行比较.结果表明,膜渗透性、离子截留率及pH差均与膜的流动电位有关,混合溶液较单一溶液的离子传递特性有一定程度的变化.     

多巴胺及KH-561改性PVDF超滤膜的制备及性能

采用聚多巴胺与亲水物质前驱体同步水解的方法,在膜表面生成杂化涂层,通过调整3-(2,3-环氧丙氧基)丙基三乙氧基硅烷(KH-561)与多巴胺的配比,制备了PVDF超滤改性膜。测试了杂化涂层对改性膜的表面形貌、亲水性、纯水通量、截留率等性能的影响。结果表明,杂化涂层不仅提高了改性膜的表面亲水能力,也改善了膜内部孔道的亲水性,PVDF改性膜的水接触角降至37.8°。膜水通量达到174 L/(m²·h),蛋白截留率达90%以上。杂化涂层在膜表面形成一层水膜,使膜具有良好的抗污染性能,改性膜的衰减系数最低可达0.19。     

pH对荷电有机超滤膜处理金属离子溶液的影响

分别以NaCl、KCl、MgCl2、CaCl2和AlCl3溶液为背景电解质液,测定了聚砜中空纤维超率膜（截留分子量为6k）的流动电位、膜渗透性、离子截留率及pH值差（pH渗透液-pH截留液）,并考察pH值对这些参数的影响;在此基础上,研究不同pH环境中离子混合溶液的超滤行为,并与单一溶液进行比较。     

络合-超滤技术处理含铜废水

络合剂为聚丙烯酸钠,超滤膜采用芳香聚酰胺膜,研究了络合.超滤处理含铜废水的工艺条件.研究了不同溶液pH值条件下聚合物/盒属离子质量比(P/M)、溶液PH、操作压力、运行时间等操作参数对铜离子去除率和膜通量的影响.结果表明,在一定pH条件下,Cu~(2+)的截留率随P/M的增加而增加;在一定P/M下,适当提高溶液pH值有利于Cu~(2+)的截留.在溶液pH=6、P/M=22条件下,Cu~(2+)的截留率达到97%以上.     

纳滤海水软化性能及膜污染研究

高硬度、浊度和总固溶物(TDS)含量的海水水质是制约海水淡化的瓶颈,孔径介于反渗透和超滤之间、具有荷电性质的纳滤膜在海水软化方面具有明显优势,利用小型平板膜测试设备,以人工海水为研究对象,进行了纳滤海水软化试验研究,考察了操作压力,运行时间对膜通量的影响和膜对海水中主要离子的截留效果,进而对膜污染进行了分析与探讨.结果表明,两种荷负电纳滤膜具备良好的渗透性和分离性能.随着运行时间的延长,膜通量和离子截留率呈现一定下降趋势;结合扫描电镜和能谱的测试结果分析发现,高离子强度的海水体系中,腐植酸的优先吸附和硫酸钙晶体的形成是造成膜分离性能下降的原因,而钙与腐植酸之间的络合效应对其影响甚微.     

Use of Liquid Chromatography for Studying Reverse Osmosis and Ultrafiltration

Abstract

A method of observing the preferential adsorption of solute or solvent onto a polymer surface by liquid chromatography is illustrated, and the results are discussed in relation to the solute separation by reverse osmosis and membrane fouling. This method shows the existence of a preferentially adsorbed water layer at the polymer-solution interface, where its amount and thickness depend on the polymer material. The adsorption data of undissociated organic solutes indicate that cellulosic materials are intrinsically less susceptible to fouling by such solutes than synthetic polymer materials. It is also shown that the steric repulsion involved in the solute's distribution between the interfacial water phase and the bulk water phase is not sufficient to describe the solute transport through the membrane, and an additional steric effect associated with the frictional force working on the solute molecule in the membrane pore has to be considered.     

Facile surface modification of PVDF microfiltration membrane by strong physical adsorption of amphiphilic copolymers

To endow the surface of poly(vinylidene fluoride) (PVDF) microfiltration (MF) membranes with hydrophilicity and antifouling property, physical adsorption of amphiphilic random copolymers of poly(ethylene glycol) methacrylate (PEGMA) and poly(methyl methacrylate) (PMMA) (P(PEGMA‐r‐MMA)) onto the PVDF membrane was performed. Scanning electron microscopy (SEM) images showed that the adsorption process had no influence on the membrane structure. Operation parameters including adsorption time, polymer concentration, and composition were explored in detail through X‐ray photoelectron spectroscopy (XPS), static water contact angle (CA), and water flux measurements. The results demonstrated that P(PEGMA‐r‐MMA) copolymers adsorbed successfully onto the membrane surface, and hydrophilicity of the PVDF MF membrane was greatly enhanced. The antifouling performance and adsorption stability were also characterized, respectively. It was notable that PVDF MF membranes modified by facile physical adsorption of P(PEGMA₅₈‐r‐MMA₃₃) even showed higher water flux and better antifouling property than the commercial hydrophilic PVDF MF membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3112–3121, 2013     

Insights into membrane fouling implicated by physical adsorption of soluble microbial products onto D3520 resin

Membrane fouling is a major problem in membrane bioreactors(MBRs). In this study, membrane fouling caused by membrane rejection and adsorption was study. Filtration tests indicated that membrane rejected SMP, causing membrane pore blockage and then forming a gel layer. Batch adsorption experiments showed that adsorption of SMP onto PVDF membrane was a spontaneous physical adsorption process.Meanwhile, the absolute value ΔG of adsorption of SMP onto D3520 was higher than that of adsorption of SMP onto PVDF membrane, so SMP preferentially adsorbed onto D3520 rather than PVDF membrane. Thus, the effect of ARs on reducing the SMP concentration was investigated. It was found that, 6 g of D3520 was suitable for adsorption of SMP. This physical adsorption involved external film diffusion, intra-particle diffusion, and surface adsorption. The Redlich–Peterson isotherm model performed best in terms of describing this equilibrium data. The mechanism of membrane fouling mitigation was verified by MBR simulation system. A case study of AR–MBR system was conducted. The results showed that addition of D3520 can effectively alleviate the development of membrane fouling.     

Polymer-bound flavins: 2. Immobilization of linear flavin-containing polyelectrolytes by adsorption onto silica

The adsorption of quaternary ammonium derivatives of linear polystyrene, containing pendant flavin groups, from aqueous solution onto nonporous silica particles was studied. It is shown that interaction takes place between the quaternary ammonium groups in the polymer and ionized silanol groups on the silica surface. Since the maximum specific adsorption was not influenced by the content of quaternary ammonium groups, relatively few quaternary ammonium groups appear to be necessary to bind the copolymers to the silica surface, probably resulting in a large fraction of segments located in loops and tails. The reactivity of the bound flavin, as estimated from kinetics of aerobic oxidation of 1-benzyl-1,4-dihydronicotinamide (BNAH) in aqueous solution, is not influenced by the adsorption process. The immobilized reactive polymer can easily be re-used several times without loss of activity, indicating that desorption of the polymer can be neglected.     

Preferential adsorption of bovine fibrinogen dimer onto polymer microspheres having heterogeneous surfaces consisting of hydrophobic and hydrophilic parts

The adsorption onto polymer microspheres of bovine fibrinogen (BFb) containing both dimeric and monomeric species was examined using various homopolymer, copolymer, and poly(2-hydroxyethyl methacrylate)/polystyrene composite microspheres which were produced by the emulsifier-free (seeded) emulsion polymerization technique. The preferential adsorption of the BFb dimer was clearly observed in an optimum region of the surface hydrophilicities of the polymer microspheres. The preferential adsorption of the BFb dimer onto the composite polymer microspheres having heterogeneous surfaces with both hydrophilic and hydrophobic parts was more remarkable than that onto the homopolymer and copolymer microspheres having homogeneous surfaces. The behavior is discussed in comparison with those for bovine serum albumin and human γ-globulin.     

Influence of the acid–basic character of oxide surfaces in dispersants effectiveness

Physical–chemical surface character has been described as a determinant factor in adsorbing polyelectrolytes onto oxide surfaces. Since basically composed by hydroxyl groups, the acidity or basicity induced by the bulk lattice in such groups seems to be of great relevance in the adsorption process. The influence of such properties in the adsorption of polyacrylic acid derivated polymers onto SnO₂ and Al₂O₃ surfaces is, therefore, studied in this paper. Polyacrylate acid molecules are observed to hardly adsorb onto the SnO₂ surface but strongly adsorb, as reported previously, onto the alumina surface. This behavior is explained based on the pronounced difference in relation to the acidity of both surfaces and, in this sphere of thought, a basic polymer (Chitosan; CS) is discussed as a functional dispersant for powders with acid surface character, such as SnO₂. Zeta potential measurements showed that this polymer raises the SnO₂ potential to +30 mV without pH variations.     

药物偶联亲和高分子微球对牛血蛋白吸附性能研究

在制备亲和高分子乳液微球基础上,对其进行空间臂改性和药物分子偶联制得PSGN-MTA亲和高分子微球药物。为研究亲和高分子微球生物相容性,考察了高分子微球药物在缓冲液中药物释放行为及对BSA蛋白吸附能力。结果表明,亲和微球表面化学键合MTA药物浓度较高且分布均匀时,对BSA蛋白的吸附过程较符合一级动力学方程。还考察了pH值对BSA蛋白吸附的影响,中性条件时PSGN-MTA微球对于BSA吸附效果较好。     

Solvent-dependent adsorption of phenolic resin onto silica substrate

The solution impregnation route is commonly exploited to prepare polymer-based composites. However, the adsorption of polymer components is complicated, which is the result of interactions between reinforcement, solvent and polymer. In this study, the adsorption of phenolic resin onto silica substrate from different solvents was investigated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, UV-visible absorption spectroscopy and thermogravimetric analysis (TGA). Isotherms for phenolic resin adsorption from solvents onto silica substrate have been examined as a function of phenolic resin content in different solvents. The viscosity and surface tension were measured for the solution systems before and after adsorption. Hydrogen bonding interaction was considered to be operative in the resin–solvent–silica system. The adsorption of phenolic resin is dependent on its relative affinity for the solvent on one hand and for the silica surface on the other. UV-visible absorption spectroscopy results suggested that phenolic resin forms hydrogen bonds with the solvent, which competes with the hydrogen-bonding adsorption mechanism for phenolic resin occurring on silica surface. This hydrogen bonding in solution along with the competitive adsorption of solvent onto silica surface suppresses the adsorption of phenolic resin and such suppression is unfavorable in a solution impregnation process.     

氨基表面修饰的高分子乳液微球对牛血白质BSA吸附性能的研究

以苯乙烯St和甲基丙烯酸环氧丙酯GMA为单体,两性偶氮类化合物V50为引发剂,运用功能单体多段加料的无皂乳液聚合法制备亲和高分子乳液基球PSG,并选择双氨基封端的聚乙二醇作为空间臂分子,进行表面修饰反应,考察了高分子乳液微球对牛血蛋白BSA的吸附性能,并着重研究了吸附时间和温度、BSA初始浓度、离子强度等因素对吸附反应的影响。实验结果表明,空间臂表面修饰的高分子微球作为载体材料,固定药物分子等生物活性物质,可通过控制吸附条件,如pH,温度,反应时间等,减少蛋白质分子的非特异性吸附,且保持生化分子的较高活性。     

Surface immobilization of polymer brushes onto porous poly(vinylidene fluoride) membrane by electron beam to improve the hydrophilicity and fouling resistance

Poly(vinylidene fluoride) (PVDF) membrane was pre-irradiated by electron beam, and then poly(ethylene glycol) methyl ether methacrylate (PEGMA) was grafted onto the membrane surface in the aqueous solution. The degree of grafting was significantly influenced by the pH value of the reaction solution. The surface chemical changes were characterized by the Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). Combining with the analysis of the nuclear magnetic resonance proton and carbon spectra (¹H NMR and ¹³C NMR), PEGMA was mainly grafted onto the membrane surface. Morphological changes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The porosity and bulk mean pore size changes were determined by a mercury porosimeter. The surface and bulk hydrophilicity were evaluated on the basis of static water contact angle, dynamic water contact angle and the dynamic adsorption process. Furthermore, relative high permeation fluxes of pure water and protein solution were obtained. All these results demonstrate that both hydrophilicity and fouling resistance of the PVDF membrane can be improved by the immobilization of hydrophilic comb-like polymer brushes on the membrane surface.