Construction of Bioinspired, Multifunctional, Durable, and Superhydrophobic Sponges for Oil–Water Separation Based on Recycled Flexible Foam

Abstract

Abstract Aiming at simultaneously settling the problem of waste resource recycling, oily wastewater pollution/health risk, flammability, and durability of traditional oil–water separation materials, this work developed the superhydrophobic/superoleophilic sponge materials (P/APP@ZIF-8@PDA@PU), which were inspired by natural lotus leaves and mussels. The results suggested that the water contact angle (WCA) and oil contact angle (OCA) of P/APP@ZIF-8@PDA@PU reached 154.3 ± 1.1° and ∼0°, respectively. The joint action of PDA/APP@ZIF-8 and PDMS in manufacturing hierarchical roughness and reducing the surface energy of sponges was confirmed. Most of all, the oil/water separation flux and efficiency of P/APP@ZIF-8@PDA@PU for n-hexane/water mixture were still as high as 43,263 L m–2 h–1 and 99.3% even after 20 cycles, indicating that P/APP@ZIF-8@PDA@PU possessed good oil–water separation performance and cyclic separation stability. After 20 adsorption/release cycles, the adsorption capacity of P/APP@ZIF-8@PDA@PU was still as high as 23.58 g/g, which demonstrated good resistance to oil clogging. Moreover, P/APP@ZIF-8@PDA@PU possessed good mechanical stability and chemical durability through a series of sandpaper rubbing, tape stripping, acid-alkali-salt immersion, and washing experiments, which could simulate the effectiveness of oil/water separation materials in practical application scenarios. Compared with PU, the total heat release rate (THR) of P/APP@ZIF-8@PDA@PU was reduced by 32.8%, and the combustion time was extended to 65 s before self-extinguishing, which was expected to solve the fire safety problem of PU materials in the process of usage, storage, and transportation. Thus, this paper exploits an effective and fluorine-free route for synchronously achieving the goals of resource recycling and wastewater treatment.