Development of a highly hydrophilic nanofiltration membrane for desalination and water treatment Original Research Article

Thin film composite (TFC) co-polyamide membranes were modified by adding carboxyl group to the polypiperazinamide backbone. The sodium chloride, sodium sulphate, magnesium chloride and magnesium sulphate rejections were measured at various feed pressures for the modified and unmodified membranes. The pure water permeability was improved as much as 20% for the modified membrane. Besides, the membrane rejection ability towards divalent ions was excellent compared to the monovalent ions. The rejection of multivalent ions was more than 96% at the operating pressure as low as 450 kPa. The modified membrane was more negatively charged compared to the unmodified membrane. The membranes developed can be used for pre-treatment in a desalination plant as well as for hardness removal in water treatment process at a higher production rate.