Carboxyl-rich UiO-66-(COOH)2 MOF-modified ceramic membranes with anti-fouling resistance toward oil-in-water emulsions based on surface charge

• Published in: Separation and purification technology 2025-07, Vol.361, p.131334, Article 131334
• Main Authors: Yang, Shengkai, Zeng, Jianxian, Yan, Sicong, Zhang, Rui, Huang, Xiaoping, Yuan, Zhengqiu, Liu, Guoqing
• Format: Article
• Language: English
• Subjects: Anti-fouling resistance; Carboxyl groups; Ceramic membrane; Coulomb force; Cross-flow filtration; Defect modulation; UiO-66-(COOH)2
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.131334

[Display omitted] •The structure of incomplete-coordination linkers in metal–organic frameworks was discovered.•A metal–organic framework variant with high carboxyl groups density was synthesized.•The special anti-fouling resistance of membranes to emulsions carrying the same charge to membrane surface.•Modified membranes can be reused and recycled by collaborative cleaning of interface force and Coulomb force. Metal-organic frameworks (MOFs) are increasingly utilized to Improve the separation performance of membranes by adjusting their structure and pore dimensions. However, MOF-modified membranes suffer from unsatisfactory permeate flux during the treatment of oily wastewater. In this study, we present a straightforward and potent methodology for fabricating MOF-modified ceramic membranes with high permeation flux, good hydrophilicity, and strong surface zeta potentials. A special missing linker, UiO-66-(COOH)2 with an incomplete-coordination linker structure, was achieved through solvent modulation. This modulation variant has a greater abundance of carboxyl groups than the other UiO-66-(COOH)2 variants, resulting in greater anti-fouling resistance of the modified membrane. Moreover, a ceramic membrane modified with this variant was used to reject emulsified oils. The modified membrane demonstrated a remarkable selectivity (∼95.8 ± 0.7 % of oil rejection) in the separation of anionic oil-in-water emulsions, while maintaining a superb pure water flux (∼1534.3 ± 91.3 L m−2h−1), about one-third of the pure water flux of the base membrane (∼4884.7 ± 88.2 L m−2h−1). After hydraulic cleaning, the anionic emulsion flux and rejection of the membrane was recovered to 65.0 L m−2h−1 and 99.0 %, respectively. In particular, the membrane possessed good anti-fouling resistance to emulsions that carry the same charge as the membrane surface, which was attributed to electrostatic repulsion. These findings show that MOF membranes can be customized to suit different emulsions. Therefore, the MOF-modified ceramic membrane has potential applications in the separation of oily wastewater.