A Ni-MOF-integrated magnetic-responsive superhydrophobic sponge for simultaneous capture of microplastics and oils: From experimental validation to DFT-based interaction mechanisms

In recent years, the increasing discharge of microplastics (MPs) and oil pollutants into aquatic environments has posed serious ecological and health concerns, driving the urgent need for efficient and sustainable removal technologies. In response to this challenge, this study successfully prepared a multifunctional superhydrophobic sponge (HFNA) with photothermal conversion capability and magnetic responsiveness via a simple dip-coating method, which can be used for the adsorption of microplastic particles (MPs) and oil pollutants in aquatic environments. By introducing polydopamine (PDA) onto the melamine sponge (MF) skeleton, incorporating high specific surface area Ni-MOF, and adding Fe 3 O 4 with magnetic driving capability, the material’s adsorption capacity toward MPs was enhanced. The HFNA achieved a maximum removal efficiency of 99.3 % for MPs and exhibited excellent removal performance for various oil pollutants, while its photothermal effect effectively reduced crude oil viscosity, improving adsorption efficiency. Subsequently, the adsorption mechanism of the material was further revealed through density functional theory (DFT) calculations. The analysis showed that Ni-MOF and MPs exhibit excellent HOMO-LUMO energy level matching, with a small energy gap (ΔE gap ), facilitating electron transfer from MPs to Ni-MOF. At the same time, electrostatic potential and charge distribution maps indicated the presence of multiple high electron affinity sites on the surfaces of Fe 3 O 4 and Ni-MOF, which help in the enrichment of MPs. Theoretical results were highly consistent with experimental data, establishing a complete correlation mechanism from electronic structure to adsorption performance and material construction, thus providing important theoretical support for the rational design of MOF-based adsorbent materials.