Controllable preparation of novel PPTA/UiO-66-NH2 nanofiltration membrane with nanoscale striped structure for dye wastewater separation

In terms of nanofiltration (NF) membrane development, the properties of membrane substrates and thin-film composite (TFC) structures have become an important factor to determine the separation performances of NF membrane. In this paper, the method of interfacial polymerization assisted by spacer spraying was used to construct the striped structure at nanometer scale. Nanoscale striped structure was prepared successfully on PPTA (poly( p -phenylene terephthamide)) NF surface with 1.3 g/L of UiO-66-NH 2 in the aqueous phase, and the morphology gradually changed to “point shaped” structure when 2.6 g/L of UiO-66-NH 2 in the aqueous phase. The optimized PPTA/UiO-66-NH 2 NF (PU4) membranes were used for dye/salt separation of methylene blue (MB). Compared with the nascent PPTA NF membranes, it showed a higher MB rejection rate of 98.6%, along with permeation flux of 19.79 L/m 2 \(\cdot\) h \(\cdot\) MPa. The salt separation order of the PU4 membrane was Na 2 SO 4  > MgSO 4  > MgCl 2  > NaCl. The rejection rates were 96.3%, 85.4%, 53.2%, and 18.4%, respectively. Under strong acid and alkali conditions, the separation performance was rejected 86.5%, better under alkaline conditions. More importantly, after a six-time recycle, the PU4 membrane showed no significant change in separation performance, suggesting its excellent stability. The novel strategy in this study provided an approach to develop advanced UiO-66-NH 2 membranes toward sustainable molecular separation in environmental applications. Graphical abstract