Attenuated thermal-regulated interfacial polymerization towards polyamide nanofiltration membrane with unprecedentedly enhanced performance

The desirable performance of polyamide membranes for seawater/brackish desalination seeks not only high water permeance, but also the pursuit of high salt rejection. However, few techniques have been able to achieve their simultaneous enhancement so far. In this work, we developed a special attenuated thermal-regulated interfacial polymerization (ATRIP) and unraveled the effect of dynamic change temperature on the microstructure of the polyamide membrane. During the ATRIP process, the interfacial temperature experiences a rapid rising and falling, which induces the formation of reaction intermediates of various sizes. The fusion of these reaction intermediates creates a dense polyamide (PA) layer with granular nanostructures on both front and back surface. These convex granular nanostructures create numerous cavities for shortening the water transport path. Therefore, the resulted TFC PA NF membrane from ATRIP exhibits unprecedented increase of permeate flux from 54 to 174 Lm−2h−1 and the increase of MgSO4 rejection from 82.9% to 95.8%. Overall, using attenuated thermal to regulate the IP process provides an effective and simple avenue to break through the “trade-off” relationship between water permeance and salt rejection of TFC PA NF membrane, which can strongly promote the development of desalination technologies.