MFI-type zeolite membrane on hollow fiber substrate for hydrogen separation

High performance MFI-type zeolite membranes on the outer surface of α-Al 2 O 3 hollow fibers were synthesized by secondary growth method using pure silica sol without an organic template. X-ray diffraction was used to characterize the phase structure of both the seed layer and zeolite membrane. The morphologies of the seed layer and zeolite membrane were examined by scanning electron microscopy. The zeolite membrane achieved an extraordinary H 2 /CO 2 separation factor of 10 with a high H 2 permeance of 5.56 10 -7 mol m -2 s -1 Pa -1 at 723 K.     

Evaluation of humic acid removal by a flat submerged membrane photoreactor

A flat submerged membrane combined with a TiO 2 /UV photocatalytic reactor (FSMPR) was employed in batch mode to remove humic acid (HA). HA removal efficiency was characterized by UV 254 absorbance, UV-vis spectra, dissolved organic carbon (DOC) concentration, specific UV absorbance (SUVA), and trihalomethane formation potential (THMFP). The FSMPR process was effective in removing more than 86% of DOC and nearly 100% of UV 254 absorbance, while the THMFPs of samples were reduced to < 19 μ g/L after 150 min of treatment. In addition, changes in transmembrane pressure (TMP) with and without UV were evaluated; TiO 2 /UV was effective at controlling membrane fouling by HA. Analysis of the molecular weight (MW) distributions and three-dimensional excitation-emission matrix (EEM) fluorescence spectra of HAs revealed that the effectiveness in membrane fouling control is a result of changes in HA molecular characteristics. The TiO 2 /UV photocatalytic reactor caused the degradation of high MW, hydrophobic humic-like molecules to low MW, hydrophilic protein-like molecules, although this fraction was not completely removed during 150 min of treatment and was less responsible for membrane fouling.     

1 kW自呼吸PEMFC堆控制因素试验

自呼吸质子交换膜燃料电池(PEMFC)阴极侧湿度和温度耦合严重,且空气流量对湿度和温度影响不同,从而使得对电池输出电压的控制变得复杂.以氢气压力和提供阴极空气流量的风扇转速为影响因素,对相应的工作点集进行了正交试验研究.分析结果表明,风扇转速高于极值电压转速时,空气会带走更多的水分,从而使得质子交换膜逐渐干燥,阻抗增大,电池性能衰减;风扇转速低于极值电压转速时,空气流量带走的热量减少,使得阴极表面温度升高,阴极端相对湿度迅速减低,从而导致质子交换膜迅速干燥,电池性能衰减迅速.因此,每个工作点存在一个使电池电压最高的风扇转速值.     

PAN中空纤维超滤膜污染与膜阻力测定

对膜污染问题进行了研究,指出浓差极化、滤饼层形成和膜孔堵塞是造成膜污染的主要原因。同时测定了PAN膜阻力．试验结果表明,PAN膜超滤过程中主要阻力来源为膜孔吸附、凝胶层及浓差极化等引起的膜污染阻力,占总阻力的71．61％。膜自身阻力和不可逆阻力分别占与总阻力的28．39％和11．76％,所占与比例较小,有利于实际应用。     

无泡曝气工艺实验研究

实验研究了中空纤维膜向水中进行无泡曝气的工艺过程,结果证明,这是一种高效的新型曝气工艺技术,其供氧的总传质系数可以达到605h-1,是传统气泡曝气方式的6倍以上;水流速和气体压力是影响无泡曝气供氧能力的2个主要变量,通过控制气压可以定量调节曝气量。     

固定化植物酯酶-显色剂传感膜的制备与性能

采用聚乙烯醇(PVA)与四乙氧基硅烷(TEOS)通过原位溶胶-凝胶法制备了PVA/SiO2有机/无机杂化溶胶,并将显色剂和植物酯酶分散于溶胶中,干燥成膜,得到一类透明度高、亲水-亲丙酮性可调、贮存性好的传感膜.该传感膜在乙酸-α-萘酯溶液中,会于可见光520 nm处出现一个新的吸收峰.传感膜在制备后的12天内活性明显下降,之后基本保持稳定,并且冷藏活性下降率要比室温保存的小很多.但不论是冷藏还是在室温下保存,被固定在杂化膜中的酶活稳定性都比在溶液状态下的明显提高.     

粉末活性炭-超滤膜工艺净化松花江水

为了研究超滤(UF)技术对地表水的处理效果,建造了一座120吨/天的中试规模的膜处理水厂.以松花江水为水源,用粉末活性炭(PAC)吸附作为超滤的预处理工艺,组成了PAC-UF系统.结果表明:PAC-UF工艺的出水浊度在0.15NTU左右,而且不受进水浊度的影响;原水不经过PAC吸附直接超滤时,膜出水有机物浓度和膜进水有机物浓度存在线性关系;UF对UV254的平均去除率在10%左右,对溶解性有机碳(DOC)的平均去除率在8%左右;加入PAC吸附后对有机物的去除有明显提高.     

RS-485总线在地电数据采集系统中的使用

介绍以Visual Basic6.0的MSComm控件为开发工具,使用自定义的通讯协议实现计算机与单片机基于RS-485总线的串口通信系统的设计。给出了RS-485串行通信系统的硬件结构、自定义通信协议、单片机的程序设计方法以及计算机通信程序的部分源代码,并通过具体应用证明了本系统的可靠性。     

气体分离用聚合物膜材料基团的设计与性能

采用基团贡献法和自由体积模型,分析了聚合物基团对膜分离性能的影响,比较了不同聚合物基团对O2和N2选择性和渗透性的贡献,预测了特定基团聚合物对O2和N2的分离性能。通过设计聚合物基团,改进了气体分离用膜材料的性能,计算结果与文献数据吻合良好。     

Phytanic acid impairs mitochondrial respiration through protonophoric action

Refsum disease is a rare, inherited neurodegenerative disorder characterized by accumulation of the dietary branched-chain fatty acid phytanic acid in plasma and tissues caused by a defect in the alphaoxidation pathway. The accumulation of phytanic acid is believed to be the main pathophysiological cause of the disease. However, the exact mechanism(s) by which phytanic acid exerts its toxicity have not been resolved. In this study, the effect of phytanic acid on mitochondrial respiration was investigated. The results show that in digitonin-permeabilized fibroblasts, phytanic acid decreases ATP synthesis, whereas substrate oxidation per se is not affected. Importantly, studies in intact fibroblasts revealed that phytanic acid decreases both the mitochondrial membrane potential and NAD(P)H autofluorescence. Taken together, the results described here show that unesterified phytanic acid exerts its toxic effect mainly through its protonophoric action, at least in human skin fibroblasts. Received 4 August 2007; received after revision 26 September 2007; accepted 10 October 2007 J. C. Komen, F. Distelmaier: These authors contributed equally to this work.