MBR对污水中肠道模型病毒的去除效应

采用重力出流式膜生物反应器(MBR)对生活污水进行处理, 选择两种孔径的微滤膜考察其对污水中T4和f 2两种模型病毒的去除情况. 清水试验结果表明, 两种膜孔径组件对T4和 f 2病毒的实际截留率远大于理论截留率; 两种膜组件对T4病毒的截留均高于f 2病毒. 在MBR稳定运行状况下, 两种不同孔径的膜组件对同一病毒的截留效果无显著差别: 孔径为0.1 mm的聚丙烯(PP)和孔径为0.22 mm的聚偏氟乙烯(PVDF)对T4去除率均大于5.5 lg; 对f 2的去除率大于3.0 lg. 其原因是膜表面的滤饼层、凝胶层在病毒的截留中起了重要的作用. 膜生物反应器对病毒的去除由膜的截留、污泥絮体的吸附和生物灭活等作用共同完成. 进一步的研究发现: 活性污泥系统对病毒去除率稳定在97％以上, 主要依靠生物灭活作用完成对病毒的去除.     

聚苯乙烯-聚甲基丙烯酸甲酯-甲苯体系的光散射性质

本文研究了不同组成聚苯乙烯、聚甲基丙烯酸甲酯混合物甲苯溶液和聚苯乙烯在不同浓度的聚甲基丙烯酸甲酯-甲苯体系中的光散射。试样聚苯乙烯是经过二次重复分级的级分;聚甲基丙烯酸甲酯是经过三次重复分级的级分。由于聚甲基丙烯酸甲酯的折光指数和甲苯相同,聚甲基丙烯酸甲酯分子对溶液的散射光强没有贡献。从90°,45°和135°三个角度的散射光强测定计算得到聚苯乙烯级分的重均分子量和均方末端距,在所有情况下都相同,而曲綫斜率,受聚甲基丙烯酸分子的存在而降低。实验结果表明溶液中聚甲基丙烯酸甲酯的存在,对聚苯乙烯的〈M〉_w和〈h~2〉~(1/2)_z没有影响。     

超临界CO_2诱导相转化法制备聚苯乙烯膜及膜体系的相图计算

以甲苯为溶剂,利用超临界CO_2诱导相转化法制备了多孔非对称聚苯乙烯膜.通过扫描电镜对膜结构进行了表征,探讨了不同温度、压力和铸膜液中聚苯乙烯浓度对膜形态、孔径分布及膜孔隙率的影响;同时,基于Tompa扩展的Flory-Huggins聚合物溶液理论计算了聚苯乙烯/超临界CO_2/甲苯铸膜体系的三元相图.研究表明,在温度为35~65℃、压力为8~16 MPa及聚合物质量分数为15%~35%条件下,制备的聚苯乙烯膜截面呈胞腔状孔结构,孔隙率为53.54%~84.67%,且孔隙率随温度、压力和聚苯乙烯浓度均呈现出先增大后减小的趋势.相图计算结果表明,温度对体系双节线位置的改变影响较小,而压力对其影响相对较大.     

聚醚砜/纤维素晶体共混膜材料及其超滤性能

聚醚砜与纤维素晶体等共混成铸膜液,采用浸没沉淀相转化法制备聚醚砜/纤维素晶体共混膜材料.通过超滤装置检测复合膜的水通量、截留率、平均孔径、孔隙率、抗污染性等超滤性能,从而讨论了纤维素晶体含量对共混膜超滤性能的影响.采用抗张测试机、热重分析仪(TGA)、原子力显微镜(AFM)对共混膜的力学性能、热稳定性能、形貌结构进行表征.结果表明,随着纤维素晶体的含量的增加,共混膜的纯水通量先升高后有所降低,截留率均保持在91%～95%,抗张强度、断裂伸长率先增大后有所下降,抗污染性较纯聚醚砜膜显著提高.当纤维素晶体质量分数为1%时,纯水通量达到最大为813.3L·m-2·h-1,孔隙率为88.8%,平均孔径达为70.9nm,抗张强度为7.25MPa,断裂伸长率为11.6%,平均污染度FR值为22.0%,衰减系数m值为35.8%.共混膜具有由纤维素晶体、聚醚砜热降解分别引起的两个失重阶段.共混膜为典型非对称膜结构,表皮层较为致密,多孔支撑层孔径较大.     

改性氧化石墨烯膜的制备及其性能研究

为了改善氧化石墨烯(GO)膜的低渗透性和不稳定性,本文采用过氧化氢对GO进行改性后抽滤成膜,并在不同温度下对膜进行热还原。采用超高性能全自动气体吸附仪、透射电镜、扫描电镜、拉曼光谱仪、接触角、X射线衍射等对材料进行结构和形貌表征。分析不同HGO(H_2O_2改性GO)负载量和不同温度热还原对膜水通量和截留率的影响。在优化条件(1mg HGO负载量、120℃还原温度)下制备的膜的水通量(397.8L·m~(-2)·h~(-1)·bar~(-1))和截留率(90%)达到最佳;并且,热还原之后的HGO膜比GO膜和HGO膜有更好的稳定性。     

以聚偏氟乙烯为基底的高渗透选择性聚酰胺/酯纳滤膜的制备与表征

以亲水性聚(N-羟乙基丙烯酰胺)(PHEAA)、疏水性聚甲基丙烯酸甲酯(PMMA)为链段的两亲性三嵌段共聚物PHEAA-b-PMMA-b-PHEAA(PHMH)为改性剂,以聚偏氟乙烯(PVDF)为基底膜材料,利用非溶剂诱导相分离法制备了PVDF/PHMH基底.与未改性PVDF基底相比,PVDF/PHMH基底表面孔径变小,孔隙率和亲水性增加;与PVDF基底纳滤膜N0相比,通过界面聚合制备的PVDF/PHMH基底纳滤膜N1表面粗糙度大、亲水性强、截留分子量小,N1纳滤膜对Na₂SO₄的截留率为96.0%,水渗透通量高达304 L·m^-2·h^-1·MPa^-1,优于商业化纳滤膜的渗透选择性.     

纳滤膜对电解质溶液分离特性的理论研究(I): 单一电解质溶液

电解质溶液在纳滤膜中的截留率对于膜法海水淡化和重金属离子的脱除非常重要. 本文假定膜具有狭缝状孔, 采用扩展Nernst-Planck方程、Donnan平衡模型和Gouy-Chapman理论来描述电解质溶液中离子在膜孔内的传递现象. 使用纯水透过系数、膜孔径及膜表面电势来表征纳滤膜的分离特征, 这三个参数可通过Levenberg-Marquardt方法由实验数据关联得到. 本文使用该模型计算了两种商用纳滤膜(NF45和SU200)对1-1型(NaCl, KCl, LiCl), 2-1型(K₂SO₄)和2-2型(MgSO₄)单一电解质溶液的截留率, 并与实验数据进行了比较, 两者吻合较好. 计算结果表明电解质溶液中离子在纳滤膜孔内传递的主要机理是离子的扩散和电迁移, 纳滤膜对电解质溶液中离子的分离效果主要由空间位阻和静电效应决定. 该模型在低浓度时对电解质溶液通过纳滤膜的截留率计算结果较准确, 但对高浓度电解质溶液则偏差较大.     

氧离子导体钼酸镧β→α相变非等温动力学的确定

为了研究氧离子导体钼酸镧La_2Mo_2O_9在853K左右存在的可逆固-固相变过程,采用差热分析(DTA)测量不同冷却速率下高温β相到低温α相的DTA曲线,运用FWO法、Ozawa迭代法、Criado-Ortega法以及atava-esták法求算相变过程的表观活化能E、指前因子A和最概然动力学机理函数G(x)"动力学三因子"。研究结果显示:β→α相变的表观活化能与转化分数有关,其值随转化分数的增大而逐渐减小,该结果表明该相变不属于一步简单反应,其过程和机理都较为复杂。不同温度区间β→α相变的G(x)不同,816~812K时,G(x)为[-ln(1-x)]2/5,对应lg A为68.28;809~804K时,G(x)为[-ln(1-x)]2/3,对应lg A为42.07。     

TiO_2/PVDF复合中空纤维膜的制备和表征

采用相转化法制备了二氧化钛 (TiO2 ) 聚偏氟乙烯 (PVDF)复合中空纤维膜 .应用牛血清白蛋白截留实验、扫描电子显微镜、热重分析、X射线衍射分别对复合膜的分离性能、微观结构、热稳定性和晶相组成进行了分析 .结果表明复合膜的性能与纯PVDF膜的相比有显著的改善 ,其中对牛血清白蛋白的截留率从 3 2 7%提高到 86 6 7% ,单根纤维的断裂应力从 3 35MPa提高到 4 70MPa ,提高了 4 0 3% .氮气吸附实验测定的孔径分布进一步表明复合膜的孔径分布变窄 ,孔径变小 .     

含非平面结构共价有机骨架分子筛分膜的界面聚合制备 及其分子筛分性能研究

以均三水杨醛和三(4-氨基苯基)胺为反应单体,在对甲苯磺酸的催化下,通过界面聚合法制备了一种含有非平面结构单元的共价有机骨架（COF）分子筛分膜,其分子结构、宏观形态和筛分性能经UV-Vis, IR, XRD和AFM表征。结果表明：COF分子筛分膜孔径约1.4 nm,厚度为65 nm,能够在酸碱条件下以及乙腈、N,N-二甲基甲酰胺、甲醇等极性溶剂中稳定存在;COF膜对乙腈、乙醇、甲醇、正丁醇、水以及N,N-二甲基甲酰胺的通量分别为31.02, 27.14, 22.24, 14.11, 12.01, 8.12 L·m^-2·h^-1·bar^-1; COF分子筛分膜对于大分子体积的甲基蓝截留率达98.1%,对分子体积小于孔径的对硝基苯胺不具有拦截作用,展现了良好的分子筛分属性。     

非电解质聚合物与烷基硫酸钠同系物间团簇化临界浓度的变化规律

用表面张力 (γ)法研究了非电解质聚合物聚乙烯吡咯烷酮 (PVP)或聚乙二醇 (PEG)与烷基硫酸纳同系物中十四烷基硫酸钠 (SMS)、十二烷基硫酸钠 (SDS)及十烷基硫酸钠 (SDeS)间团簇化临界浓度的变化规律 .上述软物质团簇的γ lgc曲线均具有双拐点即拟双平台特征 ,表明在双拐点之间非电解质聚合物与烷基硫酸钠形成软物质团簇 .对应于双拐点有两个表面活性剂临界浓度值c1 和c2 ,且符合c1 相似文献   

致密皮层非对称气体分离膜的制备

以湿相转化法制备出分离性能优良的致密皮层非对称气体分离膜；建立了醋酸纤维素 丙酮 甲醇三组分制膜体系，所制得的致密皮层醋酸纤维素非对称气体分离膜，在室温、０５ＭＰａ进气压力下，该膜对ＣＯ２／ＣＨ４的分离系数３０，ＣＯ２透气速率可达１８×１０－８ｃｍ３（ＳＴＰ）／ｃｍ２·ｓ·Ｐａ；扫描电镜图显示该膜表层致密、超薄（约２００ｎｍ）、支持层疏松，为理想结构的非对称气体分离膜．     

Cellulose Derivatives Membranes as Supports for Immobilisation of Enzymes

Cellulosic derivatives (cellulose acetate, cellulose propionate and cellulose acetate-butyrate) as membranes, were prepared in different ways. These were then characterised by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and contact angle evaluation. Subsequently, catalase (H2O2:H2O2 oxireductase; EC 1.11.1.6), alcohol oxidase (Alcohol:oxygen oxireductase; EC 1.1.3.13) and glucose oxidase (-D- Glucose:oxygen 1-oxireductase; EC 1.1.3.4) were covalently linked to these membranes. The catalytic activity and stability of these enzymes, when immobilised, were examined. The results obtained showed that the immobilisation efficiency and the stability of the coupled enzymes could be correlated with the studied properties of the supports. The cellulose acetate membrane which was prepared by evaporation gave the more active conjugate support-enzyme. Membranes prepared by the immersion technique were more crystalline and therefore less suitable for enzyme immobilisation. The highly hydrophobic membranes, obtained from the propionate and the butyrate esters of cellulose reduced the activities but gave better storage stability.     

固定HCG抗体膜的跨膜电位

高分子膜作为一项新兴技术,在很多领域得到日益广泛的应用.近十几年,随着生物工程和生物传感器的迅速发展,高分子生物功能膜的研究倍受重视.高分子生物功能膜是采用固定化技术,将具有分子识别功能的材料(如酶、抗原、抗体等)固定在高分子膜上而制得的.在固定化膜表面发生的生物化学反应,可以引起膜的荷电状态的变化,从而导致跨膜电位的变化。有关固定化膜的报导较多,但主要限于固定化的方法及其应用方面的研究,而有关高分     

Elimination reactions of (E)-2,4-dinitrobenzaldehyde O-benzoyloximes promoted by R2NH/R2NH2(+) in 70 mol % MeCN(aq). Change of reaction mechanism

Elimination reactions of (E)-2,4-(NO(2))(2)C(6)H(3)CHNOC(O)C(6)H(4)X (1) promoted by R(2)NH/R(2)NH(2)(+) in 70 mol % MeCN(aq) have been studied kinetically. The reactions are second-order and exhibit Bronsted beta = 0.27-0.32 and |beta(lg)| = 0.28-0.32. The result can be described by a negligible p(xy) interaction coefficient, p(xy) = partial differential beta/partial differential pK(lg) = partial differential beta(lg)/partial differential pK(BH) approximately = 0, which describes the interaction between the base catalyst and the leaving group. The negligible p(xy) coefficients are consistent with the (E1cb)(irr) mechanism.     

Structure and microporous formation of cellulose/silk fibroin blend membranes: Part II. Effect of post-treatment by alkali

Blend membranes (RCF1) were prepared from mixture solution of cellulose and silk fibroin (SF) in cuoxam by coagulating with acetone–acetic acid (4:1 by volume). The blend membranes were subjected to post-treatment with 10% NaOH aqueous solution, and their structure and properties were characterized by FT-IR, X-ray diffraction, DSC, SEM and DMTA. In previous work, cellulose/SF blend membranes (RCF2) prepared by coagulating with 10% NaOH aqueous solution formed a microporous structure, in which the SF as a pore former was almost completely removed from the membrane. However, when the blend membranes RCF1 were immersed in 10% NaOH aqueous solution for post-treatment, a strong hydrogen bonding between cellulose and SF inhibited the removal of SF. Although alkali is a good solvent for SF, the blend membranes RCF1 such obtained from cellulose and SF were alkali resistant. The crystallinity and the mean pore size of the blend membranes slightly decreased with increasing post-treatment time. This work provided a cellulose/silk blend membrane, which can be used under alkaline medium.     

The effects of transition metal complexes on the permeation of small gas molecules through cellulose acetate membranes

Cellulose acetate (CA) membranes containing RuCl₃·3H₂O and RhCl [P(C₆H₅)₃]₃ were prepared reproducibly. Such membranes, on treatment with CO, formed metal-carbonyl species at relatively low temperature. The Ru-carbonyls formed in CA were quite stable at 40°C in comparison with the Rh-carbonyl species and, interestingly, there was no permeation of CO gas through the ruthenium-containing CA membrane at 40°C. However, the permeation of other gas molecules, such as H₂, N₂ and O₂, through the same membrane was reduced only slightly, probably due to the cross-linking effect of the transition metal complexes in CA. It was found that essentially pure H₂ gas could be recovered from a 1: 1 mixture of H₂ and CO gases using ruthenium-containing cellulose acetate membranes.     

Sulfonated polystyrene grafted polypropylene composite electrolyte membranes for direct methanol fuel cells

Polypropylene (PP)-g-sulfonated polystyrene (SPS) composite membranes were prepared by grafting polystyrene (PS) on microporous polypropylene membranes via plasma-induced polymerization. Grafting of polystyrene was established not only inside the pores but also on the surface of PP membranes, followed by the sulfonation reaction. The chemical and physical structure of PS-g-PP membranes was investigated using FTIR and SEM. The thickness and weight of the composite membrane increased with increasing grafting time. Ion exchange capacity (IEC), ion conductivity, and methanol permeability coefficient were measured and analyzed according to grafting reaction and sulfonation time. While both the ion conductivity and methanol permeability coefficient increased with grafting amount, the characteristic factor was comparable to that of Nafion^®.     

Optimisation of ambient and high temperature asymmetric flow field-flow fractionation with dual/multi-angle light scattering and infrared/refractive index detection

Asymmetric flow field-flow fractionation (AF4) enables to analyse polymers with very high molar masses under mild conditions in comparison to size exclusion chromatography (SEC). Conventionally, membranes for AF4 are made from cellulose. Recently, a novel ceramic membrane has been developed which can withstand high temperatures above 130 °C and chlorinated organic solvents, thus making it possible to characterise semicrystalline polyolefins by HT-AF4. Two ceramic membranes and one cellulose membrane were compared with regard to their quality of molar mass separation and the loss of the polymer material through the pores. Separating polystyrene standards as model compounds at different cross-flow gradients the complex relationship between cross-flow velocity, separation efficiency, the molar mass and peak broadening could be elucidated in detail. Moreover, the dependence of signal quality and reproducibility on sample concentration and mass loading was investigated because the evaluation of the obtained fractograms substantially depends on the signal intensities. Finally, the performance of the whole system was tested at high temperature by separating PE reference materials of high molar mass.     

In situ analysis and imaging of aromatic amidine at varying ligand densities in solid phase

We report the development of a fast and accurate fluorescence-based assay for amidine linked to cellulose membranes and Sepharose gel. The assay is founded on the glyoxal reaction, which involves reaction of an amidine group with glyoxal and an aromatic aldehyde, leading to the formation of a fluorophore that can be analyzed and quantified by fluorescence spectroscopy and imaging. While the assay has been reported previously for aromatic amidine estimation in solution phase, here we describe its adaptation and application to amidine linked to diverse forms of solid matrices, particularly benzamidine Sepharose and benzamidine-linked cellulose membranes. These functionalized porous matrices find important application in purification of serine proteases. The efficacy of a protein separation device is determined by, among other factors, the ligand (amidine) density. Hence, a sensitive and reproducible method for amidine quantitation in solid phase is needed. The glyoxal reaction was carried out on microbead-sized Sepharose gel and cellulose membranes. Calibration curves were developed for each phase, which established linearity in the range of 0–0.45 μmol per mL amidine for free amidine in solution, 0–0.45 μmol amidine per mL Sepharose gel, and 0–0.48 μmol per mL cellulose membrane. The assay showed high accuracy (~ 3.4% error), precision (RSD < 2%), and reproducibility. Finally, we show how this fluorescent labeling (glyoxal) method can provide a tool for imaging membranes and ligand distribution through confocal laser scanning microscopy.

Graphical abstract