A cellulose-based nanofiltration membrane with a stable three-layer structure for the treatment of drinking water

摘要

Nanofiltration membrane (NFM) is an effective and advanced semi-permeable membrane (pore size: 1 similar to 2 nm) for deep purification of drinking water due to their low operating pressure and high divalent salt ion rejection. In this work, a stable cellulose-based polyamide nanofiltration membrane (NF-PDA-RCM) with a unique three-layered structure was prepared for advanced treatment of drinking water, via the method of chemical bond connection followed by the interfacial polymerization strategy. The regenerated cellulose membrane (RCM), as the supporting layer of NFM, prepared by phase inversion method has good physical compatibility and abundant porous channels. Further, the flux of NFM can be controlled by adjusting the pore size of the RCM. Through Michael addition reaction, the supporting layer and the active layer of NF-PDA-RCM are connected by the covalent bonds, resulting in a great improvement in the stability of NF-PDA-RCM. The resultant NF-PDA-RCM has increased rejection rate of MgSO4 (enhanced about 9.3%) and water-flux (enhanced about 78.5%) compared with that of no polydopamine (PDA) modified NFM. The RCM are completely biodegradable, allowing the NF-PDA-RCM to be a promising candidate for treating drinking water.