Raw cotton fibres (RCFs) are generally scoured and bleached to remove impurities before the dyeing process, which consumes large amounts of chemicals and water. Therefore, the development of an eco-friendly dyeing technology for RCFs that avoids the need for scouring and bleaching pretreatments is highly important for both the economic and ecological reasons. Herein, we report on a green approach for industrial-scale dyeing involving salt-free coloration of RCFs using an eco-friendly ethanol (EtOH)–water (H₂O) mixture. The method involved initially allowing the RCFs to swell in the EtOH–H₂O mixture followed by dyeing in another EtOH–H₂O mixture with 95% of ethanol by volume. The results showed that the swelling solution could be reused for at least five times, and the investigated dyes exhibited superior exhaustion and total fixation levels, indicating the high rate of dye utilization and low levels of effluent discharge. The research elucidated in detail the swelling and dyeing mechanisms of RCFs in relation to the EtOH–H₂O mixture. Additionally, the industrial-scale dyeing of RCFs revealed the successful establishment and verification of the proposed coloration technology. Meanwhile, we designed and established an automatically controllable EtOH recovery system for the reuse of EtOH from the EtOH–H₂O mixture, which accelerates its industrialization. Compared with the conventional dyeing method for RCFs, this eco-friendly approach consumes fewer chemicals and energy. Therefore, the eco-friendly dyeing of RCFs in the EtOH–H₂O mixture without scouring and bleaching pretreatments is a promising approach for protecting the environment by reducing effluent discharge.

中文翻译：

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在乙醇-水混合物中对原棉纤维进行生态友好的染色，而无需洗净和漂白预处理

通常在染色过程之前将原棉纤维（RCF）洗净并漂白以除去杂质，这会消耗大量的化学药品和水。因此，出于经济和生态方面的考虑，开发避免对精练和漂白预处理的需要的用于RCF的环保染色技术是非常重要的。在此，我们报告了一种绿色环保的工业规模染色方法，其中涉及使用生态友好的乙醇（EtOH）-水（H ₂ O）混合物对RCF进行无盐着色。该方法包括首先使RCF在EtOH–H ₂ O混合物中溶胀，然后在另一EtOH–H _2中染色。O与按体积计95％的乙醇混合。结果表明，该溶胀溶液可重复使用至少5次，所研究的染料表现出优异的耗竭和总固着水平，表明染料利用率高，废水排放水平低。该研究详细阐明了RCF与EtOH-H ₂ O混合物的溶胀和染色机理。此外，RCF的工业规模染色显示成功建立并验证了所提出的着色技术。同时，我们设计并建立了一个可自动控制的EtOH回收系统，用于从EtOH–H _2中重复使用EtOH。O混合物，加速其工业化。与传统的RCF染色方法相比，这种环保方法消耗的化学药品和能源更少。因此，EtOH-H ₂ O混合物中RCF的生态友好型染色无需精练和漂白预处理就可以通过减少废水排放来保护环境。