Fabrication and characterization of 2-aminophenol-4-sulfonic acid-integrated polyamide loose nanofiltration membrane

The preparation of high-performance nanofiltration membranes with high permeability and selectivity is a great challenge. Herein, we proposed 2-Aminophenol-4-sulfonic acid (APS) and piperazine (PIP) co-deposition for the first time through the interfacial polymerization (IP) with trimesoyl chloride (TMC) to form a polyamide (PA) layer. APS-incorporated membrane had a thinner active layer (20–60 nm), larger pore size and smoother membrane surface as well as strengthened electronegative feature. The pure water permeability of the membranes reached 5.8 times that of the control membrane, up to 70.8 LMH/bar with 96.4% rejection for RB, 99.0% rejection for BSA and SA, respectively. More importantly, the optimal membrane showed pure water flux of 22.9 LMH/bar as well as 95.9% Na2SO4 rejection. The retention performance of the membrane also exhibited high dye rejections towards MB, NR, MO above 93.6%, especially 98.0%, 98.3% and 99.1% for CV, CR and RB, respectively. Almost complete removal was achieved for natural organic matters (≥99.7%) in the meanwhile. Significantly, long-term performance stability of the APS-integrated membrane was demonstrated during the 120-h continuous filtration of dye, NOM, and salt solution, respectively. This work provides a loose nanofiltration membrane with regulatable structural morphology for water desalination, surface water and wastewater treatment.