双极膜电渗析法制备1,5-戊二胺

1,5-戊二胺(C5H14N2)是生物法制备尼龙材料的重要原料，具有广泛应用前景。利用双极膜电渗析产碱技术可将盐溶液中的1,5-戊二胺盐转换为1,5-戊二胺，实现生物发酵液中1,5-戊二胺的无害化提取过程。本工作用1,5-戊二胺硫酸盐模拟生物发酵液的主要成分，探究了不同电流模式、电流密度、盐室初始浓度及杂质离子对1,5-戊二胺制备过程指标产生的影响，分析了双极膜在长时间运行后膜表面的损伤和污染情况。结果表明，料液中的硫酸根离子可以有效地被分离，在电流为3.6 A的恒流模式下，1,5-戊二胺回收率可达到97.5%以上；在电压为29 V的恒压模式下，1,5-戊二胺回收率可达到90%以上。高至3.45 kWh/kg双极膜在反复使用35次左右后，其阳离子交换层表面出现损伤的迹象，阴离子交换层表面黏附微量固体污染物。

Preparation of 1,5-pentanediamine using bipolar membrane electrodialysis

1,5-Pentanediamine found in prokaryotic and eukaryotic organisms mostly is a natural polyamine with a variety of biological activities. In recent years, 1,5-pentanediamine has been becoming a focus since it can be used as the raw material for the preparation of nylon materials by biological methods and has been produced on an industrial scale. That means nylon materials can be produced at a lower cost by using the 1,5-pentanediamine (C5H14N2) as the raw material instead of 1,6-hexanediamine (C6H16N2) made by petroleum and chemical methods and it makes 1,5-pentanediamine have a wide range of application and business prospects. To extract 1,5-pentanediamine from post-fermentation broth, many methods have been tried. With the development of electrodialysis and ion-exchange membrane, bipolar membrane electrodialysis (BMED) has been widely applicated in an amount of areas since it can decompose salt into acid and base respectively by producing OH- and H+ without adding any other chemicals. In this study three-cell bipolar membrane electrodialysis was used in the main process of separation of bio-based 1,5-pentanediamine from post-fermentation broth. Simulated broths (1,5-pentanediaminium sulfate) were used to determine the optimum duration of EDBM process. The effects of current modes, current density, initial concentration of 1,5-pentanediaminium sulfate and the impurity positive ions in 1,5-pentanediaminium sulfate on BMED were evaluated principally with respect to alkali yield and partially with respect to efficiency and energy consumption. Membrane fouling, which mainly resulted from precipitation was also considered. The result also showed that the more satisfied recovery rate can be obtained at a higher current density. Furthermore, the impurity ions like K+ occurred in 1,5-pentanediaminium sulfate had no effect on base recovery rate, but it had an impact on the speed of recovery. Ultimately, the sulfate ions in the feed solution can be effectively removed and the recovery ratio of 1,5-pentanediamine reached 97.5% with low energy consumption 3.24 kWh/kg C5H14N2 at current density 20 mA/cm2. This process is environmental benignity and sustainable without any waste generated.