Ceramic supported polyamide composite nanofiltration membrane with a glutaraldehyde cross-linked chitosan interlayer

Abstract

Interfacial polymerization has been applied to prepare polyamide (PA) membrane on ceramic substrate. However, the low compatibility of the organic PA layer with the ceramic substrate and the intrusion of the PA layer into the ceramic substrate impedes the performance of the obtained membrane. Herein, building on previous work, a thinner interlayer (a glutaraldehyde (GA) cross-linked chitosan (CCM) interlayer) is constructed on a ceramic ultrafiltration substrate (∼5 nm) for the subsequently interfacial polymerization to improve the performance of the obtained membrane. FTIR, XPS and FESEM analyses confirm the successful construction of a smooth interlayer with a thickness of ∼250 nm and the subsequently formation of a homogeneous, rough polyamide (PA) layer with a thickness of ∼15 nm. The obtained membrane has a hydrophilic surface and a negative charged property. The molecular weight cut-off (MWCO) of the obtained membrane is 404 Da. A thinner interlayer of the composite membrane leads to a water flux of 149.46 L m−2 h−1 (0.4 MPa) with rejections of Na2SO4 84.71 %, MgSO4 81.07 %, MgCl2 63.39 %, CaCl2 58.7 %, and NaCl 51.87 %. The interlayer regulates the macroporous structure of the ceramic substrate to prevent the intrusion of the PA layer. Furthermore, the interlayer enhances the connection between the PA layer and the ceramic substrate, which enhances the stability of the PA/CCM membrane (stable performance during 20 h continuous filtration). Overall, this work provides a simple way (construct a glutaraldehyde (GA) cross-linked chitosan interlayer) to prepare composite nanofiltration membranes on ceramic substrate, which has potential applications in dyes desalination.