Study of removing organic matter in drinking water by NF membrane

The properties of organic and inorganic matter removals by ESNA1-2012 nanofiltration (NF) membrane were studied. The results showed that there is close relation between the organic matter removal and the molecular weight, but the rejections don't always increase with molecular weights increased. When the molecular weight of organic matter is less than the molecular weight cutoff (MWC) of NF membrane, the differences of organic rejections are great and the mechanism controlling organic rejections is charge repulsion between membrane and organic matter. Here it is the physicochemical characteristic parameters that mainly affect the organic matter removal. When the molecular weight of organic substance is greater than the MWC of NF membrane, the organic rejections are all great and their differences are small. At the time the mechanism controlling organic rejections are size exclusion and charge repulsion. It is the molecular weight and physicochemical characteristic parameters of organics that affect the organics removal. The organic matter rejections by most NF membranes were similar while the inorganic matter rejections were widely different. When purifying drinking water, it should be sensible to select NF membrane according to the salt contents of the water sources.