Preparation of versatile lignin-based adsorbent for the removal of organic dyes and its application in wound healing

In this work, a lignin-based adsorbent with high positive charge and excellent biocompatibility was prepared by grafting quaternary ammonium groups. Firstly, the structure of quaternized lignin (QL) was characterized by 1H NMR, FT-IR, GPC, TGA, zeta potential etc. Then, the effects of adsorbent dosage, ambient temperature, stirring frequency, contact time and initial concentration on the adsorption capacity were studied in detail. The results showed that QL exhibited efficient adsorption for rhodamine B (RB), methylene blue (MB), acid blue 92 (AB-92) and congo red (CR) dyes. All adsorption processes followed the pseudo-second order and Langmuir models. The maximum adsorption capacities of RB, MB, AB-92 and CR were 41.85, 49.47, 110.53 and 134.61 mg/g, respectively. Finally, antimicrobial activity assays and cellular viability assays demonstrated the excellent biocompatibility of QL with no cytotoxic effect. In a murine wound model, QL remarkably accelerated the re-epithelialization formation and dermal closure, indicating that it could promote cell proliferation. The finding of this study provides a facile and eco-friendly strategy to construct hydrophilic and biocompatible versatile lignin-based adsorbent for removing of cationic and anionic dyes, and the adsorbent could also be applied as an effective wound dressing, protecting the organisms in water during the adsorption.