二级出水典型污染物超滤膜污染行为的分子动力学模拟研究

以6-羧基葡萄糖、半胱氨酸和水杨酸分别代表二级出水的3种典型污染物多糖(SA)、蛋白质(BSA)和腐殖酸(HA)的分子组成,通过分子动力学(MD)技术,模拟了二级出水典型污染物,与醋酸纤维素(CA)、聚醚砜(PES)、聚偏氟乙烯(PVDF)等3种主流商业膜材料之间的结合能(ΔE),作为对具有特征污染物性质的二级出水,在不同的膜材料上产生膜污染行为的判断依据.MD数据显示:PVDF结构单元与6-羧基葡萄糖和水杨酸分子间的ΔE高于半胱氨酸,而PES结构单元与半胱氨酸分子间的ΔE值高于其它分子间的组合.3种污染物在超滤膜上的过滤通量衰减及膜污染指数,证实了MD对PVDF膜上SA和HA污染性更高,而BSA在PES膜上更易产生膜污染的预测结论;分别对6-羧基葡萄糖、水杨酸、半胱氨酸与3种聚合物结构单元间的ΔE值,与SA、HA、BSA的超滤操作初始通量衰减率间进行了线性拟合,得到的拟合系数分别为0.9981、0.9555、0.7186,说明半胱氨酸作为蛋白质类代表物进行分子模拟尚有一定的不足.     

模拟酸雨对龙眼叶绿体的伤害效应

龙眼叶绿体超氧化的歧化酶（SOD）和抗坏血酸过氧化物酶（AsA-POD)活性，谷胱甘肽（GSH）和抗坏血酸含量（AsA)含量随酸雨的pH值下降而降低，膜脂质过氧化产物丙二醛（MDA）的含量则随酸雨的pH下降而增加。pH3.0的酸雨胁迫2h，SOD和AsA-POD活性，GSH和AsA含量有所增加，并随胁迫时间的延长而下降。pH3．5的酸雨处理使类整体膜崩解，叶绿体基粒片层结构混乱；pH3.0的酸雨处理的叶绿体片层结构伤害更为严重。图5图版2参21     

溶液化学特性对谷氨酸菌在聚砜膜上吸附行为的影响

研究了溶液化学特性（包括pH值，离子强度和给溶液浓度）对谷氨酸 在疏水性聚砜膜上吸附行为的影响。结果表明：谷氨酸菌在聚砜膜上的吸附符合静电作用机理；菌体在等电点时发生絮凝，是影响吸附量的重要原因；pH值愈高，谷氨酸菌的吸附量愈小；离子强度降低相同电荷物质之间的静电排斥，增加吸附，同时也降低相反物质电荷之间的静电吸附，从而降低吸附；谷氨酸菌浓度愈大，平衡吸附量也愈大。     

膜型树脂在土壤养分测试中的应用进展

回顾了离子交换树脂在土壤养分测试中的应用及其发展变迁的3个阶段;综述了国内外离子交换树脂膜（膜型树脂）的研究进展;同时对该技术未来应用的前景及其进一步发展存在的问题进行了讨论。     

模拟酸雨对森林红壤中铝的溶出及不同土层酸度变化的影响

为进一步探明酸沉降对森林红壤及生态环境的影响，模拟长沙地区降水酸度及离子组成，采用浸泡试验对两种森林红壤活性铝的释出及土壤理化性质的变化进行了研究。结果表明，模拟酸雨浸泡初期，土壤活性铝的释出量随浸泡次数的增加而增加，原始土壤pH值愈低，活性铝释出愈多；强酸度、高离子浓度（AR4）模拟酸雨对土壤中活性铝的溶出量远大于基础酸雨（AR3）及弱酸、低离子浓度酸雨（AR2）和对照酸雨（AR1）。模拟酸雨酸度愈大，对土壤pH值的影响愈明显，不同土层间，以A层土壤pH值下降最明显，B、C层土壤则下降较小。模拟酸雨模拟浸泡土壤25年后，土壤阳离子交换量均有不同程度下降，有机质含量高，原土壤阳离子交换量大的土壤下降幅度也大。     

双模板分子印迹微球的制备及其在海水溶液中的分子识别行为研究

以萘和蒽为双模板分子,以甲基丙烯酸为功能单体、二甲基丙烯酸乙二醇酯为交联剂、聚乙烯醇（PVA）为分散剂,通过悬浮聚合制备了双模板分子印迹微球.采用紫外光谱法分析了双模板分子印迹效应产生的机制,用静态吸附实验考察了印迹微球对海水中2—3环多环芳烃的吸附选择性,并以分子印迹-分散固相微萃取法分析了海水中2—3环的多环芳烃.结果表明,双模板-功能单体分子间的多位点协同作用,优化了分子印迹材料的印迹孔穴,提高了双模板分子印迹微球的分子识别能力;所制备的双模板分子印迹材料使用3次后其选择识别性能未显著降低,显示出其富集与分离海水样品中2—3环多环芳烃的良好前景.     

pH值、离子强度和粒径对氧化石墨烯稳定性的影响

氧化石墨烯(Graphene oxide, GO)表面具有丰富的官能团和较高的比表面积,能够作为膜材料应用于膜分离技术.然而,目前合成GO的技术很难保证其横向尺寸的均一性.此外,GO在自然水环境中分散性的稳定性受环境中pH值和离子强度的影响.本文研究了横向尺寸、pH值和离子强度对GO表面双电层电荷或结构组装所需的相互作用力的影响.从原位原子力显微镜(Atomic force microscope, AFM)获得的力-距离曲线(F-D)可以看出,溶液条件对DLVO力的作用.GO的双电层静电斥力随着pH值的升高而增大,这可能是由于表面官能团的电离作用增强所致.但随着离子强度的增加,双电层斥力减小,得到的数据与DLVO理论一致.通过Zeta电位和开尔文探针力显微镜(Kelvin probe force microscopy, KPFM)测量,确定了氧化石墨烯片层表面电荷的不均匀性.     

孔道电位封闭及"空穴"传递理论初探

通过对离子交换膜表面ζ电位和间歇通电时，电渗析隔室中离子变化的测定，建立了离子交换膜选择透过性的新理论，即孔道电位封闭及“空穴”传递理论。     

诺氟沙星分子印迹共混膜的制备及应用

本文以诺氟沙星为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用本体聚合法制备分子印迹聚合物,与聚砜铸膜液混合,制备出可以在低压力下对诺氟沙星有特异性截留作用的分子印迹共混膜.采用红外光谱对共混膜的结构进行表征,利用扫描电子显微镜对共混膜微观形貌进行表征.研究了聚合物的质量分数对共混膜水通量和截留率的...     

表面分子膜降低氨挥发的Logistic模型研究

通过盆钵和田间试验,研究了表面分子膜对水体氨挥发的影响。结果表明,表面分子膜可有效抑制氨的挥发,但抑制效果跟分子膜用量有关。Ｌｏｇｉｓｔｉｃ模型可以很好模拟预测盆钵试验中的氨挥发过程,通过修正氨挥发速率常数ｃ,可较好地模拟田间氨挥发过程。     

Bioinspired and biomimetic membranes for water purification and chemical separation: A review

•The history of biological and artificial water channels is reviewed. •A comprehensive channel characterization platform is introduced. •Rationale designs and fabrications of biomimetic membranes are summarized. •The advantages, limitations, and challenges of biomimetic membranes are discussed. •The prospect and scalable solutions of biomimetic membranes are discussed. Bioinspired and biomimetic membranes that contain biological transport channels or attain their structural designs from biological systems have been through a remarkable development over the last two decades. They take advantage of the exceptional transport properties of those channels, thus possess both high permeability and selectivity, and have emerged as a promising solution to existing membranes. Since the discovery of biological water channel proteins aquaporins (AQPs), extensive efforts have been made to utilize them to make separation membranes–AQP-based membranes, which have been commercialized. The exploration of AQPs’ unique structures and transport properties has resulted in the evolution of biomimetic separation materials from protein-based to artificial channel-based membranes. However, large-scale, defect-free biomimetic membranes are not available yet. This paper reviews the state-of-the-art biomimetic membranes and summarizes the latest research progress, platform, and methodology. Then it critically discusses the potential routes of this emerging area toward scalable applications. We conclude that an appropriate combination of bioinspired concepts and molecular engineering with mature polymer industry may lead to scalable polymeric membranes with intrinsic selective channels, which will gain the merit of both desired selectivity and scalability.     

酚类分子结构和纳滤膜特性对截留率的影响规律

选择21种酚类化合物作为模型污染物,分别测定了三种不同纳滤膜对酚类化合物的截留率.结果表明,酚类化合物截留率受到取代基位置、种类和膜特性的影响.对NF270膜和NF膜而言,截留率从大到小的次序为邻位>间位>对位,而NF90膜的截留率为邻位>对位;供电子取代基有增大截留率的趋势,吸电子取代基有减小截留率的趋势;孔径小、荷电量大的纳滤膜截留率更大.通过基于遗传算法的偏最小二乘回归法(GA-PLS),建立了纳滤膜对酚类化合物截留率的定量构效关系模型,通过分析回归方程,可以看出酚类化合物的pKa值对截留率影响最大,影响较大的还有偶极矩等参数.     

Effects of lithium on membrane fluidity and lipid profile in brain membranes of aluminum-treated rats

The effects of lithium (Li) supplementation on lipid profile and fluidity of cerebrum and cerebellum membranes in aluminum (Al)-treated rats were investigated. A significant decrease in the levels of total lipids and cholesterol was observed in both the regions following Al exposure, which however were significantly increased following Li supplementation. Further, glycolipids and gangliosides contents were significantly decreased in cerebrum, but increased in cerebellum following Al treatment. Interestingly, Li supplementation reversed the trends and regulated the levels of glycolipids and gangliosides. Al treatment also elevated conjugated diene formation and phospholipid levels in both cerebrum and cerebellum membranes, which however were decreased upon Li supplementation. The cholesterol/phospholipid ratio however was decreased after Al treatment and Li supplementation was able to enhance the ratio in both cerebrum and cerebellum. Further, Al treatment significantly increased the fluorescence polarization, anisotropy and order parameter, which however were normalized following Li supplementation. The levels of Al were also found to be significantly elevated in cerebrum and cerebellum after Al treatment and normalized in cerebellum following Li treatment. Therefore, the present study shows the potential of Li in regulating the changes produced by Al on membrane composition and fluidity in rat brain.     

Electrophoretic and liquid chromatographic characterization of red cell membrane proteins modified by chromate

Besides its effects of the genetic material and function, chromate also immediately affects the structure and function of cell membranes. With human erythrocytes, chromate produces alterations in cell size and shape, it impairs the anion transport function, and it causes modifications in membrane constituents. The proteins have been analysed by one‐ and two‐dimensional gel electrophoresis and by fast protein liquid chromatography (FPLC). The main chromate effects are the crosslinking of proteins including the membrane protein bands 1 and 2 (spectrin) and haemoglobin. Furthermore, a 40.000 D membrane protein fraction is modified. Chromate may react directly with membrane constituents but evidence also points to the formation of reactive oxygen compounds which in turn may react with proteins and lipids of the cell membrane.     

脂肪族及杂环分子结构和纳滤膜特性对截留率的影响规律

选择20种脂肪族及杂环化合物作为模型污染物,分别测定了三种不同纳滤膜对脂肪族及杂环化合物的截留率.结果表明,脂肪族及杂环化合物的截留率受到分子的分枝结构、环状结构、酸性和膜特性的影响:对于同分异构体,分枝结构愈多,截留率愈高;环状有机物与分子量相近的直链有机物相比,截留率明显偏高;脂肪酸的截留率高于绝大多数醇类、醚类和酮类等不离解的化合物;孔径小、荷电量大的纳滤膜截留率更高.通过基于遗传算法结合偏最小二乘回归法(GA-PLS)建立了纳滤膜对脂肪族及杂环化合物截留率的定量构效关系模型,通过分析回归方程,可以看出膜与脂肪族及杂环化合物之间的电性作用并不是影响截留率的主要因素,而分子形状和大小对截留率的影响很显著.     

Controlling various contaminants in wastewater effluent through membranes and engineered wetland

For effective wastewater reclamation and water recovery, the treatment of natural and effluent organic matters (NOM and EfOM), toxic anions, and micropollutants was considered in this work. Two different NOM (humic acid of the Suwannee River, and NOM of US and Youngsan River, Korea), and one EfOM from the Damyang wastewater treatment plant, Korea, were selected for investigating the removal efficiencies of tight nanofiltration (NF) and ultrafiltration (UF) membranes with different properties. Nitrate, bromate, and perchlorate were selected as target toxic anions due to their well known high toxicities. Tri-(2-chloroethyl)-phosphate (TCEP), oxybenzone, and caffeine, due to their different K _ow and pK _a values, were selected as target micropollutants. As expected, the NF membranes provided high removal efficiencies in terms of all the tested contaminants, and the UF membrane provided fairly high removal efficiencies for anions (except for nitrate) and the relatively hydrophobic micropollutant, oxybenzon. Through the wetlands, nitrate was successfully removed. Therefore, a fair process of combining membranes with an engineered wetland could be proposed for sustainable wastewater reclamation and optimum control of contaminats.     

Selective separation and preconcentration studies of chromium(VI) with Alamine 336 supported liquid membrane

Chromium compounds have received considerable attention because these are used extensively in such industrial applications as electroplating, steelmaking, tanning of leather goods, and corrosion inhibition. The use of supported liquid membranes (SLMs) to remove metals from wastewaters has actively been pursued by the scientific and industrial community. In the present work, the selective separation and preconcentration of Cr(VI) ions has been studied by using a commercial amine as the membrane liquid on the porous polypropylene support. Permeation experiments were conducted on a laboratory scale batch reactor made up of perspex, with a memberane fixed amid the two chambers. The flux of Cr(VI) ions was found to be maximum (3.15?×?10^?5?mol?cm^?2?s^?1) around pH 1. Above and below this pH the flux decreases. Distribution studies show that an increase in the amine concentration leads to higher distribution coefficients at fixed pH values. At pH around unity, the distribution of Cr(VI) ions into the organic phase was found to be maximum, of the order of 56.3. The Cr(VI) transport through the membrane increases with rise in temperature. In order to check the long-term efficiency of the flat sheet SLM, an experiment was conducted with higher Cr(VI) concentration (5000?ppm) for 24?h, at optimised parameters. It was observed that in 24?h, about 1/5th of the feed Cr(VI) is left over while the rest is transported. However, minute organic droplets were also seen in the feed and strip compartments, after 1 day. This observation suggested the loss of membrane liquid. The feasibility of preconcentration of Cr(VI) by using the proposed SLM parameters, was also studied by using the hollow fibre (HF) system. Highest enrichment factor (E.F) value was obtained for 50?mg?L^?1 whereby all of the metal was transported to the stripping phase and the resulting Cr concentration was 688?mg?L^?1 (E.F?=?13.8). It was observed that while treating more diluted solutions, the enrichment factor decreases. The values of E.F equal to 8.9 and 11.3 were found for initial Cr concentration of 10 and 30?mg?L^?1.     

Advancing ion-exchange membranes to ion-selective membranes: principles,status, and opportunities

● IEM ion/ion selectivities of charge, valence, & specific ion are critically assessed. ● Ion/molecule selectivities of ion/solvent and ion/uncharged solute are reviewed. ● Approaches to advance the selectivities through sorption and migration are analyzed. ● The permeability-selectivity tradeoff appears to be pervasive. ● Ion/molecule selectivities are comparatively underdeveloped and poorly understood. Ion-exchange membranes (IEMs) are utilized in numerous established, emergent, and emerging applications for water, energy, and the environment. This article reviews the five different types of IEM selectivity, namely charge, valence, specific ion, ion/solvent, and ion/uncharged solute selectivities. Technological pathways to advance the selectivities through the sorption and migration mechanisms of transport in IEM are critically analyzed. Because of the underlying principles governing transport, efforts to enhance selectivity by tuning the membrane structural and chemical properties are almost always accompanied by a concomitant decline in permeability of the desired ion. Suppressing the undesired crossover of solvent and neutral species is crucial to realize the practical implementation of several technologies, including bioelectrochemical systems, hypersaline electrodialysis desalination, fuel cells, and redox flow batteries, but the ion/solvent and ion/uncharged solute selectivities are relatively understudied, compared to the ion/ion selectivities. Deepening fundamental understanding of the transport phenomena, specifically the factors underpinning structure-property-performance relationships, will be vital to guide the informed development of more selective IEMs. Innovations in material and membrane design offer opportunities to utilize ion discrimination mechanisms that are radically different from conventional IEMs and potentially depart from the putative permeability-selectivity tradeoff. Advancements in IEM selectivity can contribute to meeting the aqueous separation needs of water, energy, and environmental challenges.     

超滤膜污染和清洗方法的研究

本文以牛血清蛋白为料液,用酸、碱和表面活性剂作为清洗剂,对聚砜、聚丙烯腈等四种不同材质的超滤膜进行了污染和清洗实验,同时还研究了不同ＰＨ值对膜清洗效果的影响,结果表明,对于季铵化聚砚膜,用ＮａＯＨ清洗效果较好,丙烯腈膜以ＨＣｌ清洗效果为好;Ｐ天等电点附近,容易引起吸附     

Comparison of CNT-PVA membrane and commercial polymeric membranes in treatment of emulsified oily wastewater

CNT-PVA membrane was fabricated and compared with polymeric membranes. The separation performance was evaluated by homemade and cutting fluid emulsions. The three membranes show similar oil retention rates. CNT-PVA membranes have higher permeation fluxes compared with polymeric membranes. CNT-PVA membrane shows higher fouling resistance. Membrane separation is an attractive technique for removal of emulsified oily wastewater. However, polymeric membranes which dominate the current market usually suffer from severe membrane fouling. Therefore, membranes with high fouling resistance are imperative to treat emulsified oily wastewater. In this study, carbon nanotube-polyvinyl alcohol (CNT-PVA) membrane was fabricated. And its separation performance for emulsified oily wastewater was compared with two commercial polymeric membranes (PVDF membrane and PES membrane) by filtration of two homemade emulsions and one cutting fluid emulsion. The results show that these membranes have similar oil retention efficiencies for the three emulsions. Whereas, the permeation flux of CNT-PVA membrane is 1.60 to 3.09 times of PVDF membrane and 1.41 to 11.4 times of PES membrane, respectively. Moreover, after five consecutive operation circles of filtration process and back flush, CNT-PVA membrane can recover 62.3% to 72.9% of its initial pure water flux. However, the pure water flux recovery rates are only 24.1% to 35.3% for PVDF membrane and 6.0% to 26.3% for PES membrane, respectively. Therefore, CNT-PVA membrane are more resistant to oil fouling compared with the two polymeric membranes, showing superior potential in treatment of emulsified oily wastewater.