改性PVDF膜在MBR中膜污染的研究

将聚偏氟乙烯膜磺化6 h,在TiO2胶体溶液中浸泡20 min,制得的TiO2改性膜纯水通量约为1 800L/m2·h,高出未改性膜250L/m2·h.通过膜生物反应器中膜阻力的测定,分析膜污染形成的原因,表明膜污染主要是浓差极化层及凝胶层引起的;通过活性污泥对膜污染机理的研究,判断出污泥的过滤过程严格符合沉积过滤定律.在膜生物反应器(MBR)中运行时,TiO2改性膜稳定通量高于未改性膜,总阻力低于未改性膜;通过扫描电镜分析,TiO2改性膜沉积层的厚度比未改性膜薄,表明TiO2改性膜的抗污染性能优于未改性膜.     

膜参数对乳化过程的影响

膜乳化法是近年来提出的一种新的乳化方法,可以制备出单分散性非常好的乳液,在各领域都有广泛的应用。但生产率低是制约该方法工业化的一个主要因素。对影响乳液形成的膜参数进行了讨论,并对膜的优化设计进行了探讨。     

BWRO复合膜和SWRO复合膜的本质对比(英文)

采用均苯三甲酰氯和间苯二胺通过界面合法分别得到苦咸水反渗透复合膜和海水反渗透复合膜。两者在低盐浓度时,对氯化钠的脱除率相近;在高盐浓度时,苦咸水反渗透复合膜对氯化钠的脱除率明显低于海水反渗透复合膜。用扫描电镜、原子力显微镜分析两者表面形态发现海水反渗透复合膜表面粗糙度更小。X射线光电子能谱分析结果表明,海水反渗透复合膜表面的羧酸根含量更多。     

浸没式膜生物反应器膜污染研究现状

简要分析了浸没式膜生物反应器(SMBR)中膜污染的机理.在文献和现场考察的基础上,对膜材料、混合液特性、操作参数与条件、膜的清洗与再生等几个主要方面的研究现状进行了分析和综述,指出目前研究的不足在于缺乏反应器结构优化及反应器内流场优化方面的研究.     

Desalination by membrane distillation adopting a hydrophilic membrane

Direct contact membrane distillation (MD) by means of composite membranes with a PVA/PEG hydrophilic layeron a hydrophobic PVDF substrate has been developed for desalination. The effects of brine temperature, salt concentration, running time and the addition of ethanol on the flux of composite membranes have been investigated. Results showed that the flux of the composite membrane did not deteriorate by adopting an additional hydrophilic membrane although durability was obviously improved. More than 99% of the separation coefficient in one run was achieved with the conductivity of the produced fresh water in the range of 6-10 μs/cm. The flux of the composite membrane retained 91% flux of substrate at 70°C, being 23.7 kg/h·m². When the brine temperature rose to 70°C, the composite membrane showed a declined concentration polarisation, with a smaller C_mb/C_b (3.89) than that of the substrate (5.79). Although the flux decreased with the increase of brine concentration, it retained 64% flux of pure water at brine solution containing 20% NaCl and was kept almost constant until 25% NaCl. In the continuous running experiments, there was no obvious drop of flux, even after adding 25% ethanol to the brine and running overnight. It is expected that adopting a hydrophilic layer can prohibit the wetting problem that faced traditional MD with hydrophobic membranes.     

水脂膜-美丽肌肤的沉默功臣

下面我们就来认识认识这个不被大家知道的重要物质. 　　一印象 　　尽管它的名字叫水脂膜或是皮脂膜,但其实却并不是一层膜.举个例子来说:如果说角质层是海绵,那么水脂膜就是海绵中的水,它“生活“在角质层中间,不是固体的,也不是人体的组织细胞.……     

直接接触式膜蒸馏过程的膜曝气强化

针对直接接触式膜蒸馏（direct contact membrane distillation,DCMD）过程存在的膜通量小及膜污染问题,设计了一种新型结构的膜蒸馏组件。以蔗糖溶液为处理液,考察了膜组件装填密度Φ、膜曝气量q、蔗糖浓度c与温度T₀对DCMD过程的影响。结果表明：随着Φ、q的增加,DCMD过程的膜通量先增大,后逐渐降低,Φ、q均存在最优值;随着c的增加,膜通量逐渐降低;随着T₀的增加,膜通量增大;对c为30%（mass）的蔗糖溶液进行DCMD法处理330 min时,膜曝气可使DCMD的初始膜通量J_initial提升24.7%、膜通量衰减率ΔJ降低55.0%,维持高膜通量的连续运行时间t₀延长4倍。主要原因是膜曝气强化了DCMD过程的传热传质,进而强化过程的分离性能;有效控制了DCMD过程的浓差极化,进而延缓过程的膜污染进程。研究结果有利于推进DCMD的工程化应用。     

反渗透膜元件及膜系统的数学模型

介绍了反渗透膜元件性能指标的差异,讨论了建立性能各异膜元件系统运行模型的必要性,给出了单支反渗透膜元件的运行数学模型,分析了并联及串联膜元件的运行数学模型,从而建立了各类膜系统结构的通用数学模型.     

微生物固定化技术—膜生物反应器膜的清洗研究

对IMO-MBR处理生活污水的膜污染进行了酸洗、碱洗及酸洗加次氯酸钠清洗的试验研究。结果显示:酸洗加次氯酸钠清洗后,膜的通量可以烣复到原通量的94%,达到清洗的目的。     

基于膜表面与界面作用的膜污染控制方法

膜污染控制是膜技术能否成功应用的关键因素之一。讨论了膜面粗糙度、亲水性和荷电性等性质对膜分离性能的影响,介绍了膜表面性质参数的表征方法,分析了颗粒污染物团聚、颗粒与胶体吸附、胶体大分子的变形等对膜污染形成的影响。最后对面向应用过程的陶瓷膜材料表面与界面控制方法进行了总结。膜污染的研究已从操作参数调节发展到表面与界面作用的控制,对提高膜分离性能,促进膜过程在更多领域的推广应用有重要意义。     

MBR膜增效剂在膜生物反应器中的应用

为减缓MBR膜污染进程并维持膜通量,采用MBR膜增效剂MPE30改善MBR系统的运行性能。现场试验结果表明:MPE30具有提高临界通量、降低操作压差、改善出水水质、提高系统抗冲击性能等作用,同时对于消除泡沫、提高污泥脱水性能也有一定效果。     

液膜技术原理及中空纤维更新液膜

液膜技术可以实现萃取和反萃的耦合,具有独特的分离优势。因为具有非平衡传质的特性,液膜技术传质推动力大,萃取相用量很少。回顾了液膜技术的原理,指出液膜技术的关键在于形成一层厚度薄且相当稳定的液膜相。分析介绍了近年来发展起来的各种液膜技术的优缺点,提出了一种中空纤维更新液膜技术,其体积传质系数比传统萃取塔的大530倍。     

Air gap membrane distillation on the different types of membrane

Seawater desalination through the air gap membrane distillation (AGMD) process shows merit for its ambient operational conditions and low energy consumption. In this paper nine types of commercially available membranes were characterized to understand the membranes more comprehensively. The density, porosity, mean pore radius, liquid entry pressure (LEP), and contact angle (CA) of the membranes were determined. AGMD experiments were performed for the membranes to investigate the membrane difference on permeation flux and salt rejection. The effects of operating parameters such as temperature, flow rate, and NaCl concentration were studied. The 0.22 μm pore size PTFE membrane showed excellent performance for its higher permeability and higher hydrophobicity than other membranes. The mass transfer coefficients for three types of PTFE membranes were calculated from the results of the experiments.     

Preparation and properties of PVDF-fabric composite membrane for membrane distillation

The flat sheet PVDF-fabric composite membrane used for membrane distillation was prepared by coating and wet phase inversion process. The composite membrane consisted of a PVDF porous membrane layer and a fabric layer. The thin polyester filament woven fabric with water-and-oil repellent finish was used as the support of composite membrane. The effects of fabric texture, PVDF concentration in casting solution and functional finishing of fabric on the preparation and properties of the composite membrane were investigated. The experimental results showed that fabric texture, PVDF concentration and functional finishing of fabric had great influence on the preparation and properties of the composite membrane. When the PVDF concentration in casting solution was 10-12% and the support fabric, with 435 warps/10 cm and 273 wefts/10 cm and the area weight of 79 g/m², was finished with 2 g/L water-and-oil repellent agent FK-501, the prepared composite membrane exhibited better performance in tensile strength, peeling strength and water vapor permeability, with mean pore size of 0.63 μm and overall porosity of 57.6%.     

膜蒸馏脱盐过程膜润湿的研究进展

膜蒸馏（MD）适合在偏远地区小规模制备淡水,有脱盐率高、接近常压操作、可利用太阳能等优势。但MD膜润湿影响了装置的运行稳定性,是制约MD脱盐应用的重要因素之一。本文介绍了MD膜润湿的评价方法,包括测定透水压力、临界膜孔润湿深度及可视化在线监测膜润湿进程等;简述了膜污染、MD操作变量、膜蒸馏形式及不同结垢晶体各因素对膜润湿的影响;从防垢和强化通量、掌握合适的膜清洗周期、物理干预及提升MD膜性能等方面分析了抑制膜润湿的措施;并分析了一些脱盐实验时间较长的MD膜润湿情况;指出具有自清洁性的光催化膜及防垢性能更强的双疏膜和Janus膜,具有抑制MD膜润湿的巨大潜力。本文有助于对脱盐过程中MD膜润湿的预测和有效控制。     

Characteristics of membrane humidifiers for polymer electrolyte membrane fuel cells

Water management plays an important role in obtaining high performance from a polymer electrolyte membrane fuel cell (PEMFC). To reduce the volume and energy consumption of widely-used bubble humidifiers, membrane humidifiers were fabricated by using an ultrafiltration (UF) membrane and Nafion membranes. The performance of the membrane humidifiers was examined as a function of gas flow rate and operating temperature. A single cell was operated using the UF membrane humidifiers exhibiting almost the same performance with that employing bubble humidifiers.     

正渗透膜生物反应器膜过滤特性研究

以氯化钠为驱动溶质,采用正渗透膜生物反应器处理模拟生活污水,系统地考察了各因素对正渗透膜过滤性能的影响。结果表明,随着驱动液浓度增加,水通量和反向盐通量也随之增加;正渗透膜活性层朝向驱动液时(AL-DS)的水通量和反向盐通量较活性层朝向原料液(AL-FS)时大;水通量和反向盐通量与错流速率正相关,在错流速率较低时增加不明显;随着活性污泥浓度增加,水通量呈下降趋势,而反向盐通量呈上升趋势。     

真空膜蒸馏过程膜参数模拟计算

为了研究膜材料对透过通量的影响,文章建立了真空膜蒸馏过程的微观传热传质模型,并利用该模型对文献中的实验数据进行了模拟,得到了比较满意的结果。进而对不同条件下膜的长度、厚度、内径以及曲折因子、传质系数进行了模拟计算,并讨论了不同膜参数对膜透过通量的影响,为真空膜蒸馏过程中膜材料的选取及合理利用提供一定的理论依据。     

微生物代谢产物对膜生物反应器膜污染的影响

针对膜生物反应器（MBR）在运行过程中溶解性微生物代谢产物（SMP）及胞外聚合物（EPS）对膜污染进行研究。实验过程中对MBR内的污泥混合液进行了定期膜阻力监测。结果表明,SMP和EPS对膜过滤阻力有负面的影响。SMP中相对分子质量分布（Mw）在3～10 kDa对膜内部阻力影响显著,SMP中Mw＞10 kDa的大分子有机物及EPS浓度对膜外部阻力影响明显。通过傅里叶转换红外光谱（FTIR）检测膜表面污染物表明,EPS主要由多聚糖、蛋白质和腐殖酸组成,而污染层中的SMP主要是多聚糖和腐殖酸。     

离子膜电解槽的最佳换膜时机

介绍了离子膜电解装置中离子膜的经济使用寿命,分析计算了更换离子膜的最佳时机。合理确定离子膜换膜时间,有利于离子膜制碱能源利用效率的提高,降低生产成本。