Unit of Environmental Engineering, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105, Israel.
Water Res. 2012 May 15;46(8):2505-14. doi: 10.1016/j.watres.2011.12.058. Epub 2012 Jan 8.
Microorganisms are retained by ultrafiltration (UF) membranes mainly due to size exclusion. The sizes of viruses and membrane pores are close to each other and retention of viruses can be guaranteed only if the precise pore diameter is known. Unfortunately and rather surprisingly, there is no direct method to determine the membrane pore size. As a result, the UF membranes are not trusted to remove the viruses, and the treatment plants are required to enhance viral disinfection. Here we propose a new, simple and effective method for UF pore size determination using aquasols of gold and silver nanoparticles. We synthesized highly monodispersed suspensions ranging in diameter from 3 to 50 nm, which were later transferred through polymer and ceramic UF membranes. The retention percentage was plotted against the particle diameter to determine the pore size for which a membrane has a retention capability of 50, 90 and 100%. The d(50), d(90) and d(100) values were compared with data obtained from conventional transmembrane flux, polyethylene glycol, and dextran tests, and with the retention of phi X 174 and MS2 bacteriophages. The absolute pore size, d(100), for the majority of tested UF membranes is within 40-50 nm, and can only be detected with the new tests. The average 1.2 log retention of hydrophilic phi X 174 was predicted accurately by models based on the virus hydrodynamic radii and d(100) pore size. The 2.5 log MS2 retention suggests hydrophobic interactions in addition to simple ball-through-cylinder geometry.
微生物主要通过超滤（UF）膜的尺寸排阻截留。病毒和膜孔的尺寸非常接近，如果要保证病毒的截留，就必须知道精确的孔径。不幸的是，也令人惊讶的是，目前还没有直接的方法来确定膜孔的大小。因此，UF 膜不能被信任去除病毒，处理厂需要增强病毒消毒。在这里，我们提出了一种使用金和银纳米粒子水溶胶来确定 UF 孔径的新的、简单而有效的方法。我们合成了直径在 3 至 50nm 之间的高度单分散悬浮液，然后将其转移通过聚合物和陶瓷 UF 膜。截留率与粒径作图，以确定膜的截留能力为 50%、90%和 100%时的孔径。将 d(50)、d(90)和 d(100)值与传统跨膜通量、聚乙二醇和葡聚糖测试获得的数据以及 phi X 174 和 MS2 噬菌体的截留率进行了比较。大多数测试的 UF 膜的绝对孔径 d(100)在 40-50nm 之间，只能通过新的测试检测到。基于病毒水动力半径和 d(100)孔径的模型准确预测了亲水 phi X 174 的平均 1.2 个对数保留率。2.5 个对数 MS2 的保留率表明除了简单的球通过圆柱几何形状外，还存在疏水相互作用。
