核孔膜在茶汤过滤中的应用

Application of nuclear track membrane in tea filtration

利用兰州重离子加速器提供的25 MeV·u^(-186)Kr^(26+)离子辐照的聚对苯二甲酸乙二醇酯薄膜蚀刻制备了多种规格核孔膜;针对饮茶时残存杯底的茶垢,用核孔膜开展了一系列茶汤过滤实验及滤后分析。过滤方法为螺旋平板小试仪上进行的死端过滤。对过滤后的茶汤和滤后膜表面分别进行了激光粒度、浊度色度、扫描电镜等分析,证明对茶汤除杂的有效性,观察截留的颗粒物形态;用流速测定的方法记录了滤膜的流速衰减过程;对流速和过滤效果俱佳的15μm核孔膜进行了在水壶中冲泡的耐久性测试,提出了核孔膜污染后可能的清洗方法。本文探讨了过滤过程初始流速对滤膜寿命的影响,指出控制初始流速是一种核孔膜过滤的优化操作,具有一定参考意义。

[Background] People keen on tasting tea are plagued by the presence of crushed impurities in the tea soup, such as particles of tea leaf and hairs of tea leaf. [Purpose] The aim is to expand the use of nuclear track membranes （NTMs） for filtration of tea soup. [Methods] Flat membrane filtration equipment with the NTM placed in is used to separate the tea soup. [Results] The colority and turbidity of tea soup after the separation decrease with the intercept aperture. The total volume of residual particles in tea soup decreases with pore size; the peaks of size distribution of particles decrease with the pore size. The flux of NTM is good and decreases with the pore size. After cleaning, membrane flux of 15-Bin NTM can be restored to more than 80% of the original. It is found that the membrane can extend the life time and improve economic efficiency by controlling the initial flow rate. [Conclusion] NTM can effectively intercept the particles larger than its pore size in the tea soup. The 15-μm NTM is the best to separate the tea soup with the excellent flux and retention effect during gravity, and 1-μm NTM is the best choice under pressure filtration.