一种求得纳滤膜截留分子量的方法

利用回归方法,建立表征纳滤膜分离性能常用的有机分子的Stokes半径(rs)与分子量(Ms)之间定量关系方程.根据提出的纳滤膜截留分子量(Mp)所对应的分子Stokes半径与膜的等效细孔半径(rp)相等的假设,得到Mp与rp之间的关系方程,即只要知道纳滤膜细孔半径就能求得Mp.通过NF270纳滤膜对葡萄糖和蔗糖的透过实验,采用细孔模型(SHP模型)和S-K模型对NF270纳滤膜的rp进行了估算,进而计算出NF270膜的截留分子量为540左右,与供应商提供的截留分子量基本相符.利用文献数据计算了几种纳滤膜的Mp,与文献报道的结果基本一致.因此,为膜截留分子量的估算提供了一种更加方便、实用的新方法.

Method for obtaining molecular weight cut-off of nanofiltration membrane

The correlation between the Stokes radius(rs) and molecular weight (Ms) was established for uncharged solutes that were usually used for the characterization of nanofiltration membrane.Based on the assumption that the membrane pore radius(rp)equals the Stokes radius of uncharged solute with molecular weight(Ms) equaling the molecular weight cut-off(Mp),Mp can be expressed as the function of rp,in other words,if rp is known,Mp can be calculated.Permeation experiments of aqueous solution of neutral solutes with spiral membrane(NF270) were conducted,and the membrane pore radius was obtained from steric-hindrance pore(SHP) model.Then Mp of NF270 membrane was worked out as about 540,which is close to 600 provided by manufacturers.In addition,the Mp calculated for other membranes are also in agreement with literature data,which shows that the method put forward by authors is reliable and it can be a new method for obtaining the molecular weight cut-off.