3D flower-like UiO-66-NH 2 @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-NH 2 @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/m 2 ∙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/m 2 ∙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.
Oily wastewater caused by the traditional oil spills and the increment of emerging lipid (such as biodiesel) pollution endangers human and nature seriously. Herein, we conceive a novel β-cyclodextrin-threated interface demulsification structural strategy to assemble superhydrophilic aramid nanofibers (ANFs) membranes for surfactant-stabilized oil-in-water emulsion separation. Aim to modify the monomers, p-Phenylenediamine (PPD) molecules were covered by β-cyclodextrin (β-CD) to form inclusion compounds. Different poly (p-phthaloyl-p-phenylenediamine) with poly-pseudorotaxane structure (β-CD@PPTA) was obtained by low-temperature solution polycondensation by adjusting the proportion of modified monomers. The corresponding β-CD@ANFs membrane was successfully fabricated by non-solvent induced phase separation. The effect of β-CD@PPD monomers on the structure, element content, surface wettability, separation performances and durability of the modified membrane were investigated systematically. The modified membranes had the superhydrophilicity and underwater superoleophobicity characteristics. The flux and oil rejection of membrane both raised with the increased added proportion of β-CD@PPD monomers. The well-designed membrane exhibited tween 60 stabilized N-hexadecane-in-water emulsion permeances over 126.59 ± 5.35 L/m 2 h with separation efficiency above 99.73%. More significantly, the membrane had long-term demulsification performance and ideal purification effect on the separation of biodiesel wastewater, showing forceful prospect in removing lipid oil pollutants from the oil-in-water emulsions. The membrane prepared by poly-pseudorotaxane modification could better serve the development of oil-in-water separation field.
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