Ecological bleaching process using ozone as alternative to hydrogen peroxide: A comparative life cycle assessment

• A comparative Life Cycle Assessment (LCA) was conducted for conventional hydrogen peroxide bleaching and ozone-based cotton bleaching. • Optimal ozone bleaching conditions were identified as 30% fabric humidity, 20 min treatment time, and 100 g/Nm³ ozone concentration. • Ozone bleaching achieved a comparable whiteness level to the conventional method. • The main environmental burden in both processes originates from the cotton fabric itself. • The use of ecological cotton further enhances the environmental benefits of ozone bleaching. Sustainability has become a key priority in industrial production. The apparel industry, particularly the cotton bleaching process, faces major sustainability challenges due to its significant contribution to water pollution and chemical waste. This study presents a comparative life cycle assessment (LCA) of two cotton bleaching processes. The conventional method using hydrogen peroxide and an alternative method using ozone. Initially, the bleaching effectiveness of ozone was evaluated relative to hydrogen peroxide. Optimal conditions for ozone bleaching, achieving comparable performance to the conventional process, were determined to be 30% fabric humidity, a treatment duration of 20 minutes, and an ozone concentration of 100 g/Nm³. A comparative LCA was then conducted to assess the environmental performance of both bleaching methods. The functional unit selected was one pair of bleached cotton pants with a whiteness index of 70. Comparative results show that ozone bleaching substantially reduces most environmental impact categories, achieving decreases of 27% in global warming potential (GWP), 84.1% in human toxicity, 27.6% in acidification, 32.3% in eutrophication potential, and 58.1% in freshwater ecotoxicity. In contrast, the conventional hydrogen peroxide process performs approximately 30% better in ozone layer depletion, largely due to the upstream electricity requirements associated with ozone generation. Sensitivity analysis further indicates that integrating renewable electricity particularly wind power substantially enhances the environmental benefits of ozone bleaching.