Abstract The redox-responsive hydrogel as a carrier has been extensively explored for the application associated with drug delivery and tissue engineering due to its super capacity holding water and unique structure for controllable release. However, similar systems for adsorption and release of dyes have been seldom reported. In this work, a novel redox-responsive hydrogel with the size around 14.9 μm was synthesized towards the adsorption of organic dyes. Carboxymethyl cellulose nanocrystals was activated first; followed by reacting with l -cysteine to generate the amide bonds. The resulting disulfide cross-linked hydrogel can rapidly response to the external oxidizing or reducing stimuli to control the process of adsorption or release of dye, i.e., methylene blue (MB). As an efficient adsorbent, the maximum adsorption capacity of the hydrogel reached 756 mg g−1 at pH 11. The experimental data were also fitted with various kinetic and isotherm models. The results indicated that the pseudo-second-order kinetic and Freundlich isotherm models fitted the MB adsorption data well; whereas the release mechanism was better described by Fickian diffusion. Overall, the redox-responsive hydrogel developed in this work is promising for adsorption and enrichment of organic dyes; and its applications could be further broadened.

中文翻译：

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氧化还原响应性羧甲基纤维素水凝胶用于染料的吸附和控释

摘要 氧化还原响应水凝胶作为载体，由于其超强的持水能力和独特的可控释放结构，在药物递送和组织工程相关应用中得到了广泛的探索。然而，很少有类似的染料吸附和释放系统的报道。在这项工作中，合成了一种尺寸约为 14.9 μm 的新型氧化还原响应水凝胶，用于吸附有机染料。羧甲基纤维素纳米晶首先被活化；然后与 l-半胱氨酸反应生成酰胺键。得到的二硫化物交联水凝胶可以快速响应外部氧化或还原刺激以控制染料，即亚甲基蓝（MB）的吸附或释放过程。作为一种高效的吸附剂，水凝胶的最大吸附容量在 pH 11 时达到 756 mg g-1。实验数据还拟合了各种动力学和等温线模型。结果表明，拟二级动力学模型和Freundlich等温线模型与MB吸附数据拟合良好；而释放机制可以用 Fickian 扩散更好地描述。总体而言，这项工作中开发的氧化还原响应水凝胶有望用于有机染料的吸附和富集；其应用范围还可以进一步扩大。在这项工作中开发的氧化还原响应水凝胶有望用于吸附和富集有机染料；其应用范围还可以进一步扩大。在这项工作中开发的氧化还原响应水凝胶有望用于吸附和富集有机染料；其应用范围还可以进一步扩大。