Nickel-cobalt hydrogen phosphate membrane with outstanding anti-crude oil-fouling capability and its microscopic anti-fouling mechanism

• Published in: Materials today chemistry 2024-10, Vol.41, p.102325, Article 102325
• Main Authors: Wei, Xinyu, Yu, Tianlu, Zhang, Yan, Song, Shiyu, Li, Jiqun, Yang, Jianlin
• Format: Article
• Language: English
• Subjects: Anti-oil-fouling; Oil/water separation; Oily wastewater; Spill treatment; Superhydrophilic
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2024.102325

Oil/water separation membranes with superior anti-fouling properties against highly viscous oils are crucial for the efficient treatment of oily wastewater. Herein, the effects of functional groups in an inorganic superhydrophilic membrane on the anti-fouling properties of the membrane are investigated. Using a facile one-step electrochemical deposition method, Ni1-xCoxHPO4·3H2O membranes were formed on a Cu(OH)2 microneedle-coated copper mesh (CCNC–P) with superhydrophilic and underwater superoleophobic properties. All CCNC–P membranes with different Co2+ contents showed outstanding anti-fouling capability for oily wastewater such as those containing crude oil. The CCNC–P(x = 0.5) membrane exhibited high separation efficiency reaching 99.7 % across five oil–water mixtures and oil-in-water emulsions, concurrently presenting an ultrahigh flux of 61695 L m−2 h−1 for crude oil–water mixture. Moreover, the membrane consistently maintained its separation performance during the long-term crude oil–water separation process. The flux decline ratio was below 1 %, and the flux recovery ratio approached 99.4 %. The CCNC–P membranes possessed superior chemical, thermal, and mechanical stability, suggesting significant potential for the industrial treatment of oily wastewater. Density functional theory calculation revealed that the HPO42− group in CCNC–P can strongly adsorb water molecules. The resultant stabilized hydration layer impeded the contact between the membrane surface and oil droplets, while the metal ions scarcely influenced the adsorption of water molecules on CCNC–P. These findings provide new insights into the development of novel oil–water separation membranes with higher anti-fouling capabilities against high-viscosity oils. A facile electrochemical deposition strategy to develop Cu@Cu(OH)2@Ni1-xCoxHPO4·3H2O membranes with outstanding anti-crude oil-fouling property, in which HPO42− group strongly adsorbs water molecules, while the metal ions scarcely influence the adsorption. [Display omitted] •A facile one-step electrochemical deposition method for preparing Cu@Cu(OH)2@Ni1-xCoxHPO4·3H2O (CCNC–P) membranes.•All CCNC–P membranes exhibited outstanding anti-crude oil-fouling capability.•CCNC–P shows robust flux recovery for crude oil/water separation.•HPO42− group instead of metal cations is responsible for the excellent water retention ability of CCNC–P.