Colorimetric Analysis of Cotton Textile Bleaching through H2O2 Activated by UV Light

The bleaching process is one of the steps of cotton fabric manufacture. Traditionally, the most common bleaching procedure is based on the use of a hydrogen peroxide (H2O2) solution in alkali pH associated with high temperature. In this study, we investigated the possibility of applying a photolysis technique, combining ultraviolet (UV) light and H2O2 in acidic pH to promote raw cotton fabric bleaching, without adding heat and stabilizers to the process. A colorimetric analysis was performed to assess the bleaching procedure in the samples. The experiment consisted in moistening cotton fabric samples with H2O2 and then illuminating them with UV light with different doses, ranging from 0.6 to 36 J cm-2. Our findings have shown that it is important to balance the hydrogen peroxide and the amount of delivered UV light to the cotton fabric in order to achieve a satisfactory whiteness without compromising the fabric mechanical properties.漂白工艺是棉织物制造工序中的重要一环。传统工艺中，最常用的漂白流程以碱性pH环境下的过氧化氢（hydrogen peroxide，H₂O₂）溶液为基础，并配合高温条件。本研究探讨了采用光解技术的可行性：该技术将紫外（ultraviolet light，UV）光与酸性pH环境下的过氧化氢相结合，用于原棉织物漂白，且无需在流程中添加热源与稳定剂。研究通过比色分析法对样品的漂白效果进行评估。实验流程为：先用过氧化氢溶液浸润棉织物样品，随后用不同辐照剂量的紫外光照射样品，剂量范围为0.6至36 J·cm⁻²。研究结果表明，需平衡过氧化氢用量与棉织物所接收的紫外光辐照剂量，方可在不损害织物力学性能的前提下获得令人满意的白度。