聚丙烯腈UF膜的微孔表面ξ电位和电荷密度

根据Helmholtz-Smoluchowski方程，由实验测定的流动电位计算聚丙烯腈ACP-0053超滤膜的ξzeta电位，并根据Gouy-Chapmann方程的，估算出膜的微也表现电荷密度。表明UF膜微孔表面ξ电位和电荷密度与电解质的种类、浓度有关。UF膜在NaCl与KCl体系的ξ电位相近，在MgCl2与MgSO4体系的ξ电位也相近，即阳离子价态和结构越相近，ξ电位越相近，但当阴离子价态较高时，也有一定影响。由膜微孔表面ξ电位和电荷密度随溶液浓度的变化关系可知，在低浓度区域，膜表面ξ电位和电荷密度较高，并出现一个峰值，之后随浓度增大而缓慢降低。     

流动电位法研究聚烯烃微孔膜在电解质溶液中的动电现象

对NaCl、KCl、MgCl2、Na2SO4、MgSO4等5种电解质溶液中2种不同微孔膜(管式聚乙烯微滤膜和管式聚丙烯腈超滤膜)的流动电位进行了实验研究。考察了电解质浓度、离子种类和价态对膜的流动电位的影响。根据Helmholtz-Smoluchowski方程和Gouy-Chapmann理论算出2种膜的微孔表面zeta电位和电荷密度。结果表明，两种微孔膜均由于离子的吸附而带有负电荷，电解质浓度、离子种类及价态对膜的流动电位、表面zeta电位和电荷密度均具有重要的影响。     

气泡的ζ电位

对气泡ζ电位的测量方法以及纯水中、表面活性剂体系中、电解质体系中气泡ζ电位的测量结果进行综述。研究表明,气泡在纯水中的等电点处于pH 1.5~3.5之间。阴、阳离子型表面活性剂会改变气泡表面的ζ电位,非离子型表面活性剂对ζ电位的影响与其结构和基团有关,当浓度达到临界胶束浓度时,ζ电位不再发生变化。无机电解质对ζ电位的影响与离子在溶液中的存在形式及吸附状态有关,pH对ζ电位的影响主要是通过影响H＋和OH-的吸附量以及溶液中表面活性剂和无机电解质的存在形式来实现。     

气泡的ζ电位

对气泡ζ电位的测量方法以及纯水中、表面活性剂体系中、电解质体系中气泡ζ电位的测量结果进行综述。研究表明,气泡在纯水中的等电点处于pH 1.5~3.5之间。阴、阳离子型表面活性剂会改变气泡表面的ζ电位,非离子型表面活性剂对ζ电位的影响与其结构和基团有关,当浓度达到临界胶束浓度时,ζ电位不再发生变化。无机电解质对ζ电位的影响与离子在溶液中的存在形式及吸附状态有关,pH对ζ电位的影响主要是通过影响H+和OH-的吸附量以及溶液中表面活性剂和无机电解质的存在形式来实现。     

胶体滴定法测定阳离子淀粉的电荷密度

应用粒子电荷测定仪 (PCD)的流动电位变化判定阳离子淀粉胶体滴定的终点。结果表明流动电位曲线敏锐地指示了低电荷密度的阳离子淀粉胶体滴定的终点。测得的阳离子淀粉的取代度与国标凯氏定氮法测得的数值相近 ,最大偏差为 0 .0 0 3。     

膜污染过程的电动电位(ζ-电位)特性分析

<正>对于膜污染机理及其解决方法的研究是膜分离技术研究领域中的一个重点问题.已有的研究主要从膜的材料特性、待分离体系的物化特性及操作方式与条件等3个方面来考察膜污     

煤的表面电位与表面官能团间的关系

测定了5种不同变质程度的典型中国动力煤在不同pH值的水介质中的ζ电位和用H₂O₂氧化后各煤种ζ电位的变化,得到了ζ电位等电点pH值;用FTIR定量表征了与煤表面电位有关的官能团以及被H₂O₂氧化后的变化;通过对模型化合物的ZINDO量子化学理论计算,得到了H⁺ 在煤表面的吸附能、相关化学键的键级、键长和净电荷分布.综合分析实验和计算的结果,确认了在水体系中煤的表面电荷为负电荷;煤的ζ电位等电点随煤化程度的提高有规律地升高;与煤表面ζ电位密切相关的负电性官能团主要是—OH基团;原煤经H₂O₂氧化后,—OH、和—COOH等官能团增多,煤表面负电性增加;H⁺在煤表面发生化学吸附,吸附能随着煤化程度的增加而增加.     

膜动电现象的研究进展

本文介绍了近十年来国内外膜动电现象的研究状况，较全面综述了膜动电现象研究的新进展，提出运用流动电位法研究膜动电现象待解决的几个问题。     

基于分子表面电荷密度分布与机器学习的混合物设计方法研究

由于混合物性能的可调控性,当前市场对其关注与日俱增。对于这类产品,基于模型的设计方法由于具有高效性以及普适性,相较于其他产品设计方法得到了更快的发展。但是对于很多性质,如气味、颜色等,准确且普适的模型尚不可得。因此,本文提出了一种基于分子表面电荷密度分布描述符（S描述符）和机器学习模型的混合物设计方法,采用描述符表征产品、再通过机器学习模型将其与性质关联,直接用于混合物产品设计。具体地,根据给定的产品性质需求,机器学习模型直接预测/设计混合物产品的S描述符;然后以欧几里德距离为指标,在给定的数据库中筛选出S描述符满足要求的候选混合物组成。最后,对候选混合物及其组分性质进行实验验证,完成设计。本文以香精的混合替代物设计作为算例,设计得到丙酸叶醇酯的两种混合香精替代物,通过实验对混合物进行了验证。结果表明,混合替代物的气味及其组分的各理化性质均与丙酸叶醇酯相近,证实本文所提出方法的有效性。     

聚丙烯腈超滤膜氩低温等离子体表面改性的研究

运用氩低温等离子体技术,对聚丙烯腈超滤膜进行表面改性。考察聚丙烯腈超滤膜随等离子体放电条件（放电功率、反应腔气压）变化的规律,测定改性前后膜透水率和截留率的变化情况,评价改性效果。     

聚醚砜中空纤维血浆分离膜的孔径大小及分布

本文采用场致扫描电镜的显微观察法和膜对溶质的粒子筛分法测定聚醚砜中空纤维血浆分离膜的孔径大小及分布。通过显微镜观察统计得到膜的几何平均孔径为229nm,膜孔孔径分布在150nm,-350nm,筛分法测试得到膜的平均孔径为197nm。平均孔径大小约为200nm的聚醚砜中空纤维膜适合做血浆分离膜。     

Pore initiation and growth on n-InP(100)

Pore growth on n-type InP(100) can be electrochemically initiated in HCl and HF solutions by polarizing the material anodic to a critical potential value—the pore formation potential (PFP). At surface defects however, the PFP is significantly lower (shifted cathodically). This is evident from simple scratch experiments as well as experiments using focused ion beam (FIB) implantation of Si²⁺ to write defined surface damage/implant patterns into n-type InP(100) substrates. These implant sites represent initiation sites for the onset of dissolution processes. Selective pore formation within the implant patterns is achieved if polarization of the n-type material is carried out anodic to the PFP corresponding to defects but cathodic to the PFP of the unimplanted surface. Furthermore, it is shown that the pore morphology depends strongly on the type of halogen acid present in the electrolyte. Scanning AES images show that the composition of the porous layers is strongly altered from the bulk composition.     

聚丙烯酸钠在中空纤维超滤膜表面的吸附研究

以KCl溶液为背景电解质液,测得聚砜中空纤维超滤膜等电点的pH值为2.9±0.1.当聚丙烯酸钠溶液pH值在等电点附近时,溶质在膜表面吸附量显著增大,导致膜通量迅速下降.研究了不同温度下膜表面吸附量随时间的变化,结果表明:吸附反应可用拟二级速率方程来描述,温度为293～308 K时,速率常数在0.359～0.604 m2·g-1·min-1内递增.考察不同pH值和离子强度对吸附过程的影响可得:当pH值为2.6～9时,平衡吸附量由0.218下降至0.012 g·m-2;当离子强度为0.0～0.1 mol·L-1时,平衡吸附量由0.218降低至0.154 g·m-2.进一步研究了平衡浓度对吸附量的影响,结果表明当聚丙烯酸钠浓度为0.05～5.0 g·L-1及pH≤4时,Langmuir吸附等温线对实验数据能较好地拟合,方程参数qm和b值的大小随膜表面吸附量的增大而增大.     

Modification of a Poly(tetrafluoroethylene) Porous Membrane to Superhydrophilicity with Improved Durability

The commercial fluorocarbon surfactant (FCS) DuPont? Zonyl 321 fluorinated cationic surfactants, was employed to modify both flat‐sheet and hollow‐fiber poly(tetrafluoroethylene) (PTFE) porous membranes. The variation of morphology, wettability, and hydrophilicity durability to acid and alkali as well as the filtration performance of both membranes were investigated. Such superhydrophilic membranes showed better wetting stability and higher resistance to acid and alkali solutions. Moreover, both membranes exhibited good filtration performance.     

PU/PVC共混超滤膜的制备及性能

采用湿法相转化制膜技术制备PU/PVC共混膜、PU/PVC/SiO2共混膜。PVC可以改变铸膜液体系在凝固浴中的分相速度,提高成膜性及改善膜的微孔结构,在此共混物中加入SiO2可以显著改善膜的微孔结构,并提高PU共混膜的水通量,可用于超滤。用扫描电镜对膜的结构形态进行了观察。     

丝状菌对膜生物反应器中溶解性有机物及膜污染的影响

该文以处理超市废水实际MBR工程为基础,通过对污泥膨胀过程中进出水、溶解性微生物产物(SMP)和胞外聚合物(EPS)中的溶解性有机物(DOM)特性的研究,发现SMP和进出水的DOM主要以蛋白质为主,且SMP较EPS含有更多大分子物质;同时发现SMP比EPS和进出水中含有更多50～100 kDa、100～500 kDa和...     

Separation of Water and Nitric Acid with Porous Hydrophobic Membrane by Air Gap Membrane Distillation (AGMD)

Abstract

This study investigates the effect of operation parameters on the separation of nitric acid‐water mixture using air gap membrane distillation (AGMD). Porous hydrophobic PTFE membrane was used. The performance was evaluated based on the permeate flux and the nitric acid selectivity. Operating parameters such as feed solution temperature, feed concentration, flow rate, and air gap width were varied. Nitric acid selectivity was found to increase with the increase in feed solution temperature, feed concentration, flow rate, and air gap width. Permeate flux increased, when the feed temperature and the flow rate were increased. The effect of recirculation of the feed solution was also studied. With the recirculation mode, at different initial solution volumes, it was observed that the nitric acid concentration in the feed and the permeate, increased. The rate of flux decline was greater, when the initial feed solution volume was lower.     

平板类脂双层膜(pBLM)的研究进展与实验技术

本文首先介绍了pBLM的概念和它的基本性质,并着重介绍了制备稳定的pBLM的实验技术,pBLM技术的发展状况以及它在诸如光能转换、离子通道、免疫学等许多领域的应用,最后介绍了pBLM技术的应用前景与展望。     

Charge storage of ternary polymer blends based on poly(phenylene ether)

BACKGROUND: Charge storage capability is a fundamental property of polymers used in electromechanical transducer applications. In this work, the charge retention of ternary blends of poly(phenylene ether) and polystyrene modified with poly(styrene‐co‐acrylonitrile), polystyrene‐block‐poly(ethylene‐co‐butylene)‐block‐polystyrene or polystyrene‐block‐polyisobutylene‐block‐polystyrene (SIBS) triblock copolymers was correlated with the blend composition, final morphology and the chemical structure of the components. RESULTS: It was determined that the charge storage capability is favoured by a finely dispersed and non‐interconnected phase and can be reduced by high polarity or low molecular weight of the blend components. Additionally, the molecular weight and the amount of styrene of the copolymers also determined the phase morphology, which in turn affected the charge retention. The use of SIBS for the ternary blends, especially in small quantities, significantly improved the charge storage. As such, 100 µm films with a surface potential of about 400 V were able to retain up to 240 V (60%) after 24 h at 130 °C. CONCLUSION: The electret behaviour of the polymer blends was influenced by a complex relationship between chemical structure, molecular weight and phase morphology. Copyright © 2009 Society of Chemical Industry