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再生纤维素膜及其微孔膜性能的比较 总被引:2,自引:1,他引:1
用微相分离法制奋不同孔径的再生纤维素微孔膜。由流速法和电子显微镜测定了它们的孔径,研究了它们的透过性和力学性能,并且与一般铜氨法再生纤维素膜进行比较。结果表明,该膜具有较好的力学强度和韧性,较高的筛分性,特别是这种膜的透水速度比一般膜高两倍。上述性能的改善可归因于微相分离法使膜形成大量直通孔道。此外,本文提出一种格子模型表示一般膜的孔径三维无规分布的维数k与膜孔隙率p_r之间的关系,由此对流速法测定平均孔半径的计算公式修正如下: 相似文献
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用于膜蒸馏苦咸水淡化的PTFE疏水膜实验研究 总被引:1,自引:0,他引:1
利用目前国内生产的PTFE疏水膜,以自来水、盐水溶液作工质进行了多层并接气隙式膜蒸馏实验,比较了几种膜的分离性能,研究了料液温度、料液流量、浓度对膜渗透通量的影响,各种膜的通量稳定性及污染情况.实验结果表明:4#膜在长期自来水、盐水实验中通量、电导率都较稳定,特别是在后期实验中,通量最大;而孔径大、涂层薄的1#膜在前期实验中通量较大,而随运行时间增长,通量有所下降,特别是盐水实验中,截留率低,电导率高,因此不适合淡化苦咸水用,综合来看4#膜性能较好.实验后各种膜表面的污染情况较严重,都有黄色沉积物. 相似文献
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膜蒸馏技术及其应用进展 总被引:44,自引:5,他引:39
引用近期发表有关文献,较全面地介绍了膜蒸馏过程的基本概念、特征、研究的现状、应用研究情况,同时包括了与膜蒸馏相关的膜过程,并对膜蒸馏技术的发展趋势作了简要的评述. 相似文献
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纳滤膜是介于反渗透膜和超滤膜之间的一种新型分离膜,其截留分子量范围相对较窄(200-1000)且孔径较小,膜材质的选择日益成为制备出高性能纳滤膜的关键。本文综述了国内外高分子纳滤膜材料发展、应用和改良的最新研究进展,并在此基础上展望了纳滤膜材料未来发展趋势。 相似文献
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ABSTRACTIn this paper, we describe a new process for the preparation of drug loaded nanocapsules using a membrane contactor which may be scaled up for industrial applications. Nanocapsules are prepared according to the nanoprecipitation method. The organic phase (solvent, polymer, oil, and drug) is pressed through the pores of an ultrafiltration membrane via the filtrate side. The aqueous phase (water and surfactant) circulates inside the membrane module, and sweeps away the nanocaspules forming at the pore outlets. Two model drugs are selected for the preparation of drug loaded nanocapsules: indomethacin and vitamin E. It is shown that indomethacin loaded nanocapsules with a mean diameter of 240 nm and vitamin E loaded nanocapsules with a mean diameter of 230 nm are obtained with a 150,000 daltons ultrafiltration membrane, a transmembrane pressure of 3 bar, and a crossflow rate of 1.7 m.s? 1. High fluxes are also obtained (around 0.6 m3/h.m2), leading to the preparation of 1.8 10? 3 m3 drug loaded nanocapsules in 8 min. The advantage of this membrane contactor compared to other processes for drug loaded nanocapsules preparation is shown to be its scale-up ability. 相似文献
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微孔Al_2O_3膜的研究进展 总被引:1,自引:0,他引:1
本文介绍了微孔Al_2O_3膜的制备方法、结构表征、表面改性及在高温气体分离和膜反应器中应用的最新进展,并结合作者的研究工作进行了一些讨论. 相似文献
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In this study, a membrane-based process was applied to simultaneously reclaim methane and generate reused water from raw domestic wastewater. The system was comprised of up-flow anaerobic sludge fixed bed (UAFB), anoxic sink (AS) and aerobic membrane bioreactor (MBR). The hydraulic retention time of UAFB (HRT(U)) was gradually shortened from 8h to 6h, 3h and to 1h, while the HRT of AS and MBR kept at 8 h. It is found that HRT(U) of 3h was more suitable for the balancing production of biogas and volatile fatty acids (VFAs), and the VFAs served as carbon source for denitrification. The trans-membrane pressure (TMP) of the MBR kept lower than 0.04 MPa without wash or change of membrane sheet, however, the scanning electron microscopy (SEM) analysis indicated that microbes attached to the inner-surface of membrane, causing irreversible fouling after 133-day operation. The denaturing gradient gel electrophoresis (DGGE) profiles of amplified 16S rDNA gene fragments proved that more functional bacteria and higher microbial diversity emerged at HRT(U) of 3h and 1h. Most bacteria belonged to Betaproteobacteria and were responsible for carbon and nitrogen removal. 相似文献
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Enhanced performance of a submerged membrane bioreactor with powdered activated carbon addition for municipal secondary effluent treatment 总被引:1,自引:0,他引:1
The aim of this study was to investigate the feasibility of PAC-MBR process treating municipal secondary effluent. Two laboratory-scale submerged MBRs (SMBR) with and without PAC addition were continuously operated in parallel for secondary effluent treatment. Approximately 63%TOC, 95% NH4+-N and 98% turbidity in secondary effluent were removed by the PAC-MBR process. Most organics in the secondary effluent were found to be low molecular weight (MW) substances, which could be retained in the reactor and then removed to some extent by using PAC-MBR process. Parallel experiments showed that the addition of PAC significantly increased organic removal and responsible for the largest fraction of organic removal. Membrane fouling analysis showed the enhanced membrane performance in terms of sustainable operational time and filtration resistances by PAC addition. Based on these results, the PAC-MBR process was considered as an attractive option for the reduction of pollutants in secondary effluent. 相似文献
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膜分离工艺作为一种绿色环保技术,具有先进、高效、低能耗的优点,在电厂锅炉补给水处理领域中得到了成功的应用。在具体工程实践的基础上,本文分析了超滤、反渗透和电去离子EDI等关键膜单元系统在电厂锅炉给水预处理、软化以及脱盐纯化中的原理与作用特点,并比较了相关工程应用中几种不同类型的商业化膜元件的性能。 相似文献
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浅谈壳聚糖及壳聚糖膜 总被引:1,自引:0,他引:1
介绍了壳聚糖膜的成膜机理,以壳聚糖的结构和性质为基础,总结了壳聚糖膜的制备方法。其中关于化学改性方面主要介绍了酰化反应、烷基化反应、酯化改性、醚化反应、羧甲基化反应、季铵化反应等。用以下几种指标来表征壳聚糖膜的特征,包括机械性能、气体选择渗透性和阻湿性、润湿性能、抑菌性、可食用性与安全性等因素。最后,重点介绍了壳聚糖膜在果蔬保鲜方面的应用,为壳聚糖膜的发展指明了一定的方向。 相似文献
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Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven to be successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate a Group 5A-Ta, Nb, V-based alloy with respect to microstructural features and hydrogen permeability. Electrochemical hydrogen permeation testing of the V-Ti-Ni alloy is reported herein and compared to pure Pd measurements recorded as part of this same study. The V-Ti-Ni was demonstrated to have a steady-state hydrogen permeation rate an order of magnitude higher than the pure Pd material in testing conducted at 22 °C. 相似文献
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Victor L. Berdichevsky 《International Journal of Engineering Science》2010,48(3):383-404
Elastic plates can be described by a two-dimensional theory, if the characteristic length of the stress state along the plate, l, is much larger than the plate thickness, h. If all elastic moduli of a laminated plate are of the same order, no matter how many lamina the plate has, then the normal to the mid-surface of the plane remains normal in the course of deformation, and the deformation of the plate can be described by the classical plate theory. The situation changes, when the elastic moduli are of different orders of magnitude. This occurs, in particular, for the hard-skin plates, i.e. the sandwich plates the faces of which are very hard. Due to the low deformability of the skin, normal fibers cannot remain normal to the mid-surface in the course of deformation. The deviations are characterized by transverse shear. The difference from the theory of transverse shear, introduced by Timoshenko and Reissner, is that the transverse shear effects are not the corrections to classical plate theory; they are the effects of the leading order. That is caused by the presence of an additional small parameter, the ratio of elastic moduli of the core and the skin. The additional small parameter changes the character of the asymptotics. In this paper, the governing two-dimensional equations for sandwich plates are derived by an asymptotic analysis of linear three-dimensional elasticity. We show that the classical plate theory works only within a certain range of parameters. Beyond that range the asymptotic theory differs from the classical one. We focus especially on the hard-skin plates, but obtain also the universal relations, which can be applied for any values of elastic moduli and the relative thickness of the skin and the core. As an example four-point bending problem is discussed. 相似文献