A facile surface modification strategy for improving the separation, antifouling and antimicrobial performances of the reverse osmosis membrane by hydrophilic and Schiff-base functionalizations

[Display omitted] •The polyamide membane is modified by a facile and mild grafting approach.•The permeate flux, fouling resistance and antimicrobial property are improved.•Schiff-base groups are introduced on the membrane surface as antimicrobial agents.•The membrane microstructures do not obviously effected by the surface modification.•The modifiers are low cost and easily available. A Schiff-base and hydrophilic functionalized polyamide reverse osmosis (RO) membrane has been fabricated by ordinally grafting ethylenediamine, glutaraldehyde, and 3-amino-1-propanol on the freshly fabricated polyamide surface under a facile mild grafting strategy. The modification process has no obvious influence on membrane thickness and morphology. Compared to the pristine polyamide membrane, the modified membrane becomes more neutral, hydrophilic and forms a “brush-like” structure on the surface, and it has higher permeate flux (ca. 49.8 L/m2h) with comparable salt rejection (ca. 98.6 %) under 1.55 MPa testing pressure with 2 g/L NaCl. The fouling resistant evaluation suggests that the modified membrane possesses excellent flux recoverability and fouling resistance to bovine serum albumin as a foulant model. It should be attributed to the presences of the abundant hydrophilic groups and grafted “brush-like” chains. The formation of the Schiff-base group (-CN-) endows the polyamide membrane with higher bactericidal rate (ca. 96.3 %) confirmed by the microbial resistant experiment using Escherichia coli as a probe. This strategy bypasses the traditional macromolecular modification routes, avoiding the permeate flux decline from the thickness and density increase of the separation layer. It has great application potential in large-scale production of the high-performance polyamide RO due to the low cost of the modifier and the facile mild modification process.