A novel fluorescent lignin-based hydrogel with cellulose nanofibers and carbon dots (CDs) was synthesized for the high-value utilization of lignin and control of hexavalent chromium (Cr(VI)). Its chemical and physical structure was characterized, and its Cr(VI) sorption performance was evaluated. The results demonstrated that 3D porous structures were constructed in this hydrogel. The maximum adsorption capacity of this hydrogel was 599.9 mg/g, and its sorption performance met Freundlich and pseudo-second-order models. Meanwhile, this novel hydrogel exhibited high sensitivity to Cr(VI), with a limit of detection of 11.2 mg/L and a wide linear range from 15 to 200 mg/L. Moreover, its mechanism for efficiently adsorbing and detecting Cr(VI) was analyzed. The results confirmed that the efficient adsorption and detection were due to these 3D porous structures generated by the lignin and cellulose nanofibers modified with CDs. The porous structures provided many active sites and ion transport channels, thereby improving the adsorption, and stabilized the fluorescence signal, thus enhancing the detection.

合成具有纤维素纳米纤维和碳点（CD）的新型荧光木质素基水凝胶，用于木质素的高价值利用和六价铬（Cr（VI））的控制。表征了其化学和物理结构，并评估了其对Cr（VI）的吸附性能。结果表明在该水凝胶中构建了3D多孔结构。该水凝胶的最大吸附容量为599.9 mg / g，其吸附性能符合Freundlich和拟二阶模型。同时，这种新型水凝胶对Cr（VI）表现出高灵敏度，检出限为11.2 mg / L，线性范围为15至200 mg / L。此外，分析了其有效吸附和检测Cr（VI）的机理。结果证实，有效的吸附和检测归因于木质素和CD修饰的纤维素纳米纤维产生的3D多孔结构。多孔结构提供了许多活性位点和离子传输通道，从而改善了吸附并稳定了荧光信号，从而提高了检测效率。