In-situ interfacial polymerization of zwitterionic nanofiltration membranes with anti-scaling performance

Mineral scaling caused by multivalent metal ions can significantly hinder the long-term operation of nanofiltration membranes. In this study, in-situ interfacial polymerization including a posttreatment by using a citric acid solution was employed in order to mitigate scaling on the membrane surface. Under the optimal conditions (15 min of posttreatment with a 2 M citric acid solution), the membrane water permeance increased from 5.76 ± 0.23 to 15.1 ± 1.8 L m−2 h−1·bar−1 for the pristine and the optimal membrane, respectively. The molecular weight cut-off of the optimal membrane was 399 Da, which allows for the removal of organic micropollutants in groundwater. Furthermore, the resulting membrane showed a Na2SO4 and CaCl2 rejection of 92.5 ± 1.9 and 11.4 ± 1.3%, respectively. During the anti-scaling tests, the membranes fabricated with this strategy exhibited a minor decline of the water permeance of 33.5% when subjected to the same water recovery process, opposed to 65.8% for the pristine membrane. This proposed fabricating procedure thus provides an effective strategy for retarding membrane scaling in desalination applications.