Wood–inspired preparation of ligninsulfonate/trimesoylchloride nanofilm with a highly negatively charged surface for removing anionic dyes

Nanofilms with a more negatively charged surface to separate anionic dyes were fabricated via the facile interfacial polymerization of natural ligninsulfonate (SLS) with some anionic groups of -SO³⁻ and trimesoyl chloride (TMC), inspired by the reinforcement structures of wood. The as-prepared nanofilm had low surface roughness and had the surface with high negative zeta potential at the pH range of 3–10. When the pH was 8, the zeta potential was up to − 88.5 mV, and it could still reach approximately − 58.1 mV even at pH of 3. The results indicated that the negatively charged SLS/TMC nanofilm could be efficiently applied for removing anionic dyes. The rejection rates of rose bengal, methyl blue, and reactive brilliant blue were all above 99.5% with a high flux. The retention performance for the separation of the anionic dye solution did not decrease under high and low pH conditions. And excellent anti-organic dye fouling performances were shown of the membrane for the separation of the dye solution owing to the enhancement of the Donnan exclusion between the anionic dye and the membrane surface. Integrating all the findings, this work provides a highly negatively charged SLS/TMC nanofilm, which has a high potential in the purification of dye wastewater, even under some harsh conditions.