Controllable preparation of acid and alkali resistant 3D flower-like UiO-66-NH2/ZiF-8 imbedding PPTA composite nanofiltration membrane for dye wastewater separation

3D flower-like UiO-66-NH2@ZiF-8 (UZ) nanoparticles have porous structural properties and multifunctional functional groups exposed on the surface, which provide significant advantages in improving compatibility with polymers and exceptional molecular sieve performance. Poly(p-phenylene terephthamide) PPTA is an acid/alkali resistant porous membrane material. However, the preparation of highly permeable and selective nanofiltration (NF) membranes is still a challenging problem due to the low permeability of PPTA NF membranes. Therefore, in this study, PPTA/UiO-66-NH2@ZiF-8 (PUZ) membranes were prepared using spacer spray-assisted interfacial polymerization. It was investigated that the effects of different additions of 3D flower-like UZ nanoparticles on the physicochemical properties and structure of PUZ membranes. The results showed that the polyamide structures with different morphologies were formed on the PUZ membranes surface by depositing 3D flower-like UZ nanoparticles at a spraying frequency of 12 min−1. When 1.3 g/L of 3D flower-like UZ nanoparticles were interval sprayed, the PUZ4 membranes surface showed a unique doughnut-like structure and featured tubular and doughnut-like interconnections. PUZ4 membranes exhibited 4.4 times higher permeance and maintained excellent dye rejection (methylene blue dye permeance up to 58.23 L/m2∙h∙MPa and methylene blue dye rejection of 99.60 %) compared to pristine PPTA NF membranes (methylene blue dye permeance up to 13.25 L/m2∙h∙MPa and methylene blue dye rejection of 92.10 %). In addition, the modified PUZ4 membranes had a great antifouling performance with a recovery ratio of 99.43 % for more than 6 cycles and a high rejection rate of 98.51 % at 0.1 MPa.