Cotton can be coloured by dyeing and printing using either dye or pigment colourants. Pigments are insoluble in water but can be dispersed in a polymer print binder and heat-fixed to the fabric. Vat and sulphur dyes similarly have low solubility in water but through alkali/reduction can be solubilised and exhausted onto the cotton fibre. Following their reoxidation, the dyes are insolubilised in the fibre and, like pigment prints, in general exhibit good wash fastness. In this study, sequential acid/alkali/peroxide or acid/dithionite/peroxide treatments were investigated as a means of removing pigment/polymer prints and common sulphur and vat dyes from coloured cotton fabric. Using the sequential acid/dithionite/peroxide treatment, up to 97% of both sulphur and vat colourants could be “stripped” from dyed cotton producing a white cellulosic feedstock material that could be used for “new” fibre regeneration. By contrast, the “stripping” of the pigment/polymer binder colourant system was less predictable and less complete and is probably a reflection of the different chemical natures of the polymer binder and pigments. This contrasting behaviour highlights the range of chemistries applied to cotton and that developing a universal single treatment to strip out all finishes may be problematic.

中文翻译：

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研究从棉纺织品中去除色素、硫磺和还原着色剂以及对废纤维素回收的影响

棉花可以通过使用染料或颜料着色剂染色和印花来着色。颜料不溶于水，但可以分散在聚合物印花粘合剂中并热固定在织物上。同样，还原染料和硫化染料在水中的溶解度较低，但通过碱/还原可以溶解并吸尽到棉纤维上。再氧化后，染料不溶于纤维，并且像颜料印花一样，通常表现出良好的耐洗牢度。在这项研究中，研究了连续酸/碱/过氧化物或酸/连二亚硫酸盐/过氧化物处理作为从彩色棉织物上去除颜料/聚合物印花和常见硫磺和还原染料的一种手段。使用连续的酸/连二亚硫酸盐/过氧化物处理，多达 97% 的硫磺和瓮着色剂可以从染色棉中“剥离”，生产出可用于“新”纤维再生的白色纤维素原料。相比之下，颜料/聚合物粘合剂着色剂系统的“剥离”不太可预测，也不完全，可能是聚合物粘合剂和颜料不同化学性质的反映。这种对比行为突出了应用于棉花的化学范围，开发一种通用的单一处理方法来去除所有饰面可能会有问题。