Sustainable Development Path of Traditional High-Pollution Bleaching Process for Animal Fibers: Key Mechanisms, Critical Influencing Factors and Bottlenecks—A Review

Animal fiber is an important raw material for textiles. Dark animal fibers cannot be directly dyed by light colors, which is difficult to meet the demand for color diversity in clothing. Therefore, bleaching is an important step in textile processing of dark animal fiber. Traditional bleaching technology has some problems such as large water consumption, long processing time and heavy metal ion pollution. This characteristic of high energy consumption, high water consumption and high pollution is in sharp contradiction with the global textile industry’s goal of energy conservation and emission reduction. Especially under the backdrop of Carbon Peaking and Carbon Neutrality Goal policy, the traditional bleaching process is now facing severe restrictions from environmental protection regulations. However, there are still deficiencies in systematically and deeply summarizing the bleaching methods for dark animal fibers from the perspectives of sustainability and environmental protection. Herein, the chemical structure of eumelanin and the essence of bleaching were elucidated. The bleaching mechanism of different dark animal fiber bleaching methods was systematically summarized, environmental friendliness and current challenges of these methods were deeply analyzed. Finally, the future outlook is proposed for the rational development of dark animal fiber bleaching method with efficiency and sustainability.