Loose nanofiltration membranes based on interfacial glutaraldehyde-amine polymerization for fast and highly selective dye/salt separation

Loose nanofiltration (NF) membranes based on the interfacial polymerization (IP) reaction between glutaraldehyde (GA) and amine are developed for dye/salt separation. Branched tris(2-aminoethyl)amine (TETA) and linear hydrazine (HZ) are chose as aqueous amine monomers. Due to the low reactivity of aldehyde and amine under room temperature, plenty of evenly distributional cavities with exposed amine groups form in the matrix, favoring to enhance the membrane permeance, hydrophilicity and dye/salt selectivity. Notably, sodium dodecylsulphate (SDS) is introduced to regulate the monomer diffusion behavior and narrow the reaction zone, facilitating the formation of thin and defect-free skin layer. The resulting GA-TETA/HZ-L membrane shows a high water permeance of 76 LMH bar−1 as well as an excellent dye/salt selectivity (99% rejection for methyl blue (MB) and 4.19% rejection for Na2SO4). Furthermore, the membrane shows a good anti-fouling property for bovine serum albumin (BSA), humic acid (HA) and sodium alginate (SA), benefiting from its smooth surface, high hydrophilicity and negative zeta potential. The newly demonstrated SDS-assisted aldehyde-amine IP process provides a novel and facile approach to develop the high-performance loose NF membrane for various fields, especially dye recycle and purification.