Resource utilization of steel slag for fabrication of Fe-MOF-based photothermal superwetting textiles with rapid viscous oil/water separation

The efficient resource utilization of inorganic solid waste steel slag is greatly desired. However, its global utilization rate remains low, underscoring the urgent need for novel and effective processing routes. In this paper, Fe-MOF was successfully synthesized using steel slag as the raw material, which was inserted into the layers of the two-dimensional material MXene to achieve a composite structure, which was then deposited onto a superhydrophilic fiber cloth made from recycled waste cotton pads. The resultant composite material exhibited superior and stable superhydrophilic and underwater superoleophobic properties through complex intermolecular forces of glycyrrhizic acid (GA)-based ligand compounds. The highly hydrophilic GA formed gel-like protecting layer, which strongly maintained the stable superhydrophilic layer of the composite. The introduction of Fe-MOF enhanced the interlayer spacing of MXene and formed heterojunctions at the interface, greatly improving electron transport between the two semiconductors and significantly promoting the photothermal response speed and intensity of the system. Under photothermal action, this composite material can be used for quick separation of viscous oil/water mixtures and emulsion systems, demonstrating excellent oil pollution resistance and cycled usage rate. This composite textile also achieved flame-retardant properties. This paper not only reported a new oil/water separation material but also provided a new pathway for the high-value utilization of steel slag and the recycling of waste cotton pads. Graphical abstract