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Bioinspired polydopamine particles-assisted construction of superhydrophobic surfaces for oil/water separation

Shang, Bin, Wang, Yanbing, Peng, Bo, Deng, Ziwei
Journal of colloid and interface science 2016 v.482 pp. 240-251
absorption, ammonia, catalysts, catechol, coatings, cotton, dopamine, energy, ethanol, hydrophobicity, melamine, mussels, netting, nylon, oil spills, oils, pollution, remediation, roughness, solvents, stainless steel
Frequent oil spillages and industrial discharge of oils/organic solvents have induced severe environmental pollution and ecological damage, and a great cost in energy and finance has been consumed to solve the problems raised. Therefore, it is urgent to develop a surface hydrophobic modification that can be applied to materials with desired properties of high separation efficiency, excellent selectivity and stable performance in extreme conditions during the oil/water separation. Herein, with combined bioinspirations from mussel adhesive protein (polydopamine) and superhydrophobic lotus leaf (hierarchical structures), we develop a general way to superhydrophobically modify various commercial materials, aiming for the selective removal of oils/organic solvents from water. In this procedure, immersing commercial materials (e.g. melamine sponge, stainless steel mesh, nylon netting and cotton cloth) into water/ethanol/ammonia mixtures at a low concentration of dopamine (DA, 2mg/mL) allows a polydopamine (PDA) coating with a tunable roughness appearing on the substrate in one step. This is because DA can self-polymerize and form PDA particles with a catalyst of ammonia, attaching to any surfaces due to abundant catechol and amine groups in PDA, and ultimately, resulting in hierarchical structures. The subsequent decoration with 1H, 1H, 2H, 2H-perfluorodecanethiol features the surface superhydrophobic and superoleophilic. This approach is straightforward and economic, and carried out under a mild, environmental-benign circumstance, with nonspecific substrate demands. In addition, the as-prepared superhydrophobic materials exhibit excellent separation performances including high absorption/separation capacity, excellent selectivity, and extraordinary recyclability for collecting various oils/organic solvents from water. These superhydrophobic materials have also verified to be highly chemical resistant, environment stable and mechanically durable. Therefore, this simplicity and versatility of the direct mussel-inspired approach may facilitate the fast development of oil/water separation materials for applications in the field of water remediation, clean-up of oil spills and oil recovery.