Pervaporation research

Membrane pervaporation is emerging as an increasingly valuable technique for solvent recovery in industry. Following last month's feature on ‘Pervaporation Developments’ we now look at the research currently being undertaken worldwide in this area.     

渗透汽化膜反应器

反应蒸馏通过去除一产物可以使反应平衡向正方向移动,因而在工业生产中得到广泛应用.但是,它是一种非常耗能的操作而且还不能用来处理热敏性的化学品和生物酶.渗透汽化膜反应器由于具有节能和高效的特性,正成为比反应蒸馏更具竞争潜力的操作单元.综合国内外的研究工作,介绍了渗透汽化膜反应器中各种亲水膜的应用概况及该类反应器应用于酯化等可逆反应中的优势,并总结了膜反应器中酯化反应的动力学模型研究.     

壳聚糖膜在渗透汽化领域的研究进展

综述了近年来壳聚糖膜在渗透汽化领域的最新研究进展.介绍了壳聚糖渗透汽化膜在有机溶剂脱水、有机混合液分离研究中的发展状况.同时,简单介绍了壳聚糖渗透汽化膜的制备技术、分离特征及存在问题.并对壳聚糖渗透汽化膜的研究方向提出建议.     

EC-HBPE渗透汽化膜的性能

以三羟甲基丙烷为核、二羟甲基丙酸为单体,采用准一步法合成了1~5代脂肪族超支化聚酯(HBPE)。将该聚酯与乙基纤维素(EC)共混制备了EC-HBPE均质膜,以苯/环己烷体系为对象,对该共混膜的溶胀行为和渗透汽化性能进行了考察。结果表明,适量3、4、5代HBPE的加入可以在不降低膜分离因子的同时,大幅度提高膜的通量。在苯含量较低(<10%)的料液中,EC-HBPE的吸附选择性略高于EC,而EC-HBPE液的平衡吸附量明显高于EC。     

Pervaporation as an alternative to headspace

The use of pervaporation as an alternative to headspace is proposed. The analytical system involves the speciation of organomercury compounds in solid samples using pervaporation, which has been coupled for the first time to gas chromatography. The speciation of mercury as Me(2)Hg, Et(2)Hg, and MeHgCl has been carried out without any derivatization of the analytes, which, after separation from the solid matrix, are preconcentrated on a Tenax minicolumn prior to desorption and chromatographic separation on a semicapillary column (HP-1) prior to atomic fluorescence detection. No column degradation was observed. Linear ranges and detection limits slightly better than those obtained by headspace GC were observed for mercury species in solid samples. Excellent recoveries (between 95 and 107%) for mercury species added to complex solid samples were obtained by this extremely simple and easily automated setup.     

渗透蒸发透水膜的研究进展

根据渗透蒸发透水材料的发展过程特征，对已有的渗透蒸发透水膜材料进行了系统综述，并对各种透水膜的渗透蒸发分离性能作了阐述．     

渗透汽化膜组件的结构特性

本文根据渗透汽化膜过程的特点,通过分析、计算、探讨了渗透汽化膜组件在结构上的特殊要求,这些要求与其它膜技术极不同,因此在渗透汽化膜组件及装置设计前,必须在实际料液操作条件下,进行长期试验,以取得设计数据和经验。     

多元酸交联聚乙烯醇渗透汽化膜

研究了交联聚乙烯醇(PVA)渗透汽化膜。所用交联剂包括:马来酸酐、草酸、柠檬酸、偏苯三酸酐、邻苯二甲酸酐及1.6己二酸。渗透汽化的结果表明,交联剂的结构对渗透汽化膜的性能有很大的影响。当使用同样当量交联剂时,交联荆的官能度越大,当量越小,膜的分离系数越大而流量越小。交联剂分子中芳香基的存在导致流量增大,分离系数下降。交联膜的热分析结果进一步证实了交联荆结构对选择分离性能的影响。     

多元酸交联聚乙烯醇渗透汽化膜

研究了交联聚乙烯醇(PVA)渗透汽化膜。所用交联剂包括:马来酸酐、草酸、柠檬酸、偏苯三酸酐、邻苯二甲酸酐及1.6己二酸。渗透汽化的结果表明,交联剂的结构对渗透汽化膜的性能有很大的影响。当使用同样当量交联剂时,交联剂的官能度越大,当量越小,膜的分离系数越大而流量越小。交联剂分子中芳香基的存在导致流量增大,分离系数下降。交联膜的热分析结果进一步证实了交联剂结构对选择分离性能的影响。     

Pervaporation membrane process for vapour absorption system

This paper describes a novel vapour absorption refrigeration system in which a pervaporation membrane replaces the conventional generator for the concentration of working fluids. The use of a pervaporation membrane gives two potential advantages to the vapour absorption system; i.e. enhanced selectivity of the components to be separated from the working fluids and a lower space requirement. Issues related to integration of a pervaporation membrane into a vapour absorption system and the performances of such a system have been investigated. The results indicate that the pervaporation membrane process could be an alternative to the distillation process that is widely used in vapour absorption systems.