An environmentally friendly and superhydrophobic melamine sponge self-roughened by in-situ controllably grown polydopamine nanoparticle for efficient oil-water separation

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2025-01, Vol.705, p.135567, Article 135567
• Main Authors: Lou, Zhuoyao, Tu, Yuanyuan, Yang, Yihao, Gui, Xuefeng
• Format: Article
• Language: English
• Subjects: Melamine sponge (MS); Oil-water separation; Polydopamine; Self-roughened; Superhydrophobicity
• ISSN: 0927-7757
• DOI: 10.1016/j.colsurfa.2024.135567

The preparation of conventional superhydrophobic sponges inevitably requires the involvement of noxious and non-degradable raw materials，thus threatening ecosystems. As reported herein, an environmentally friendly and superhydrophobic melamine sponge is facilely prepared for efficient oil-water separation, which is completely derived from eco-friendly substances. The formation of a hierarchical structure on the sponge skeleton was achieved via the in-situ controllable growth of polydopamine nanoparticles in mildly alkaline solution. In addition, octadecyl amines (ODA) with long chains of hydrophobic alkyl groups were grafted onto the polydopamine coating to reduce the surface energy through Schiff base or Michael addition reactions. Ultimately, the resulted sponge possessed extreme water repellency with a water contact angle (WCA) of 153.21 ± 1.31° and could retain its superhydrophobicity when it was exposed to solutions with different pH values and high temperature. Moreover, the resultant sponge exhibited fully reversible compressibility with up to 80 % strain and excellent structural stability after 200 cyclic compression tests. Meanwhile, distinct organic liquid absorption experiments were conducted to confirm the resulted sponge with excellent oil absorption capacity (73.46–119.66 g/g) and oil-water separation properties. Therefore, the as-prepared superhydrophobic sponge provides valuable insight into efficient oil-water separation. [Display omitted] •Non-toxic and bio-degradable polydopamine nanoparticles formed in situ and controllably on sponge skeletons•The eco-friendly polydopamine layer provides strong adhesion to the sponge substrate and a secondary reaction platform.•Superhydrophobic sponges are produced free of petroleum resources and the raw materials utilized are all non-toxic.•The sponge featured excellent superhydrophobicity and oil-water separation efficiency.