Novel poly(piperazine-amide) (PA) nanofiltration membrane based poly(m-phenylene isophthalamide) (PMIA) hollow fiber substrate for treatment of dye solutions

A novel aromatic poly ( m -phenylene isophthalamide) (PMIA) hollow fiber substrate was first introduced to poly(piperazine-amide) (PA) composite membrane for nanofiltration. Chemical composition, morphological structure and top surface property were comprehensively characterized. Analyses indicated that a negative charged polyamide selective layer was successfully synthesized on PMIA substrate via interfacial polymerization. For nanofiltration tests, the as-prepared PA/PMIA hollow fiber membrane exhibited not only a superior permeation (104.13 ± 0.70 L·m −2 ·h −1 , 0.6 MPa), but also an excellent salt rejection in the order as: R N a 2 S O 4 ${R_{\text{N}{\text{a}}_{\text{2}}}}_{\text{S}{\text{O}}_{\text{4}}}$ (98.45%) >  R MgS O 4 $R_{\text{MgS}{\text{O}}_4}$ (97.98%) >  R CaC l 2 $R_{\text{CaC}{\text{l}}_2}$ (96.02%) >  R MgC l 2 $R_{\text{MgC}{\text{l}}_2}$ (95.74%) >  R NaCl (54.07%). Additionally, nanofiltration performance was evaluated with three kinds of anionic dyes (Chromotrope FB, Reactive Yellow 3, Direct Fast Blue B2RL) in varied conditions, including operating pressure, dye content, pH environment and salty co-exist. Evidence supported that an outstanding dye-removal ability was achieved using the developed PA/PMIA membrane, which was specifically higher than 97%. Integrate all the findings, this work provided a new PMIA based hollow fiber nanofiltration membrane, which should be promising in application of dye wastewater treatment.