Enhanced Superhydrophobic Melamine Sponge with Bimetal Organic Framework for Simultaneous Oil-Water Separation and Microplastic Removal

The escalating problem of oily wastewater and microplastic pollution poses a significant threat to our environment. Addressing this challenge has been hampered by the lack of sustainable materials capable of handling multiple pollutants effectively. However, this research introduces a groundbreaking approach for designing a superhydrophobic composite sponge, MS@ZnCo-ZIF@HDTMS. Utilizing a straightforward layer-by-layer self-assembly strategy, this work achieved the robust integration of bimetallic organic framework (ZnCo-ZIF) onto the sponge surface. This integration was facilitated by the adhesive and ion exchange properties of polydopamine (PDA), thereby constructing intricate micro- and nanocomposite structures. The immense specific surface area of ZnCo-ZIF offered numerous absorption sites for the assembly of PDA and hexadecyltrimethoxysilane (HDTMS). Remarkably, the composite sponge exhibits superhydrophobic and superoleophilic properties, demonstrating exceptional oil absorption capacities ranging from 55 g/g to 96 g/g, even after enduring 50 cycles. Moreover, MS@ZnCo-ZIF@HDTMS possesses remarkable mechanical and chemical stability. Its gravity-driven oil-water separation capabilities are noteworthy, achieving a permeate flux of 10,000 L m-2 h-1 and a removal rate of up to 99.2%. Crucially, the superhydrophobic nature of the composite sponge, coupled with capillary effect, Van der Waals forces, hydrogen bonding, and other interactions, enables MS@ZnCo-ZIF@HDTMS to capture a diverse range of microplastics from water relatively swiftly. Therefore, this work not only provides effective candidates for the sustainable treatment of oil and microplastics in water but also opens new avenues for the restoration of aquatic environments.