Fabrication of eco-friendly Cu/Co-LDHs-based superhydrophobic sponge and efficiently synchronous removal of microplastic, dyestuff, and oil

Microplastics (MPs) are ubiquitous in aquatic and terrestrial environment, which pose serious threat to ecosystem and human health. Although many approaches have been developed, most of them showed low efficiency and long processing cycle. Herein, a cost-effective and eco-friendly coated sponge (HDTMS/CuCo-LDHs/PDA@Sponge) was successfully fabricated for the first time via the supersaturated coprecipitation methods, integrating of multistage lamellar layered hydroxides (LDHs) structure, polydopamine (PDA) adhesive layer, and hydrophobic agent. Among them, (i) the complexation of PDA can enhance the growth of CuCo-LDHs, (ii) the large surface area of CuCo-LDHs provided plentiful action sites for linkage of PDA and HDTMS molecules, thus self-strengthened the coating much more firmly, (iii) the cooperation of three buildings significantly promoted the adsorption capacity of coatings to various pollutants. The finally coated sponge showed mechanically durable, superhydrophobicity, salt tolerance, and antibacterial activity, which could efficiently and synchronously absorb MPs (polypropylene and polyethylene), dyestuff, and tiny oil, and the removal rates remained almost 100% for these pollutants. Moreover, the large-scale coated sponge (9 cm × 6 cm × 1 cm) could simultaneously adsorb almost 100% MPs (40 mg/L), Sudan Ⅲ (10 mg/L), and dodecane (20 mL/L) within 1 min. The absorption energy between the coatings and MPs were −1699 kcal/mol for PP and −932.8 kcal/mol for PE, respectively. The adsorption mechanism was ascribed to multiple forces, including electrostatic interaction, capillary attraction, hydrogen bond, p-π conjugation, Van der Waals force, lipophilicity, complexation, surface adhesion of PDA, and lipophilicity of HDTMS clusters. The developed superhydrophobic sponge will be a novel strategy to purify wastewater, especially for the high-salinity and microbial-rich marine environment.