Anionic channel membrane encircled by SO3H-polyamide 6 particles for removal of anionic dyes

Abstract Membranes of anion channels in matrix were constructed through amphiphilic self-assembly of polyelectrolyte, SO3H group containing polyamide 6 (SPA6). SPA6 molecules self-aggregated into 255 nm micelles with negative charges at the surface in casting solution. Micelles switched into nanofibers, which formed pompoms of divergent arrangement of nanofibers from the center after immersed in coagulation bath. They adhered and piled up to construct the membrane. Charged groups were remained at the surface of pompoms during solidification. The gaps between spheres provided channels full of anions, which supplied great repulsion to anions. It endowed membranes the potential to remove anion dyes from aqueous solution. The rejection was up to 99.73% for 500 mg/L Congo red and 85.68% for 100 mg/L Acid blue 93 and 63.06% for 100 mg/L Methyl orange after first filtration. Total removal percentage was 95.48% for Acid blue 93 and 79.51% for Methyl orange after second filtration. Self-aggregation of dye molecules also helped their high removal efficiency. Flux of film 30 M of 100 mg/L CR solution dropped to 67.34% and rejection rate was higher than 95% in 1500 min. Flux could be brought back to more than 90% of the original values after washed by deionized water, suggesting that 30 M had good anti-fouling capacity. SPA6 membranes displayed a potential for effective treatment of textile wastewater.