Due to stability in acidic and basic conditions, NF membranes can be applied in the processing of inorganic acids and in the treatment of acid waste streams. The membranes can be used in the entire pH range (0 – 14) and at temperatures reaching 70°C.
The mineral acid product quality is effectively enhanced by the use of the membrane system in the down stream processing. The membranes allow the product (acid) to pass with practically no retention (0-4%). The contaminants, such as dissolved organic molecules, which give the acid a characteristic coloration, are retained by the membrane with high retention values (>98% – 99%). In this manner a colourless acid stream, free of organic, is obtained. One popular example of this application is Decolourisation and Upgradation of Green Phosphoric Acid.