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

Lilian Moriyama,Vanderlei Bagnato,Bruno de Oliveira

doi:10.21577/0103-5053.20170235

Abstract

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.

Highlights

From the field to the consumer, cotton fiber undergoes several processes, such as: weaving or knitting, desizing, scouring, bleaching, dyeing and goods preparation
This study aimed to explore the possibility of using a photonic technique in which hydrogen peroxide in acid pH is photoactivated by different doses of UV to promote raw cotton fabric bleaching
This study showed the viability of the photonic technique applied to hydrogen peroxide in raw cotton samples and a UV light intensity in photobleaching process was evaluated, and increased bleaching is observed with the increase in UV intensity

Summary

Introduction

From the field to the consumer, cotton fiber undergoes several processes, such as: weaving or knitting, desizing, scouring, bleaching, dyeing and goods preparation. Cotton presents some natural pigments that lead it to have a yellowish brown color. This coloration may come from environmental factors like soil, dust, insects and others. The bleaching process is responsible for removing these pigments in order to make the cotton whiter.[1,2,3]. Bleaching agents are used to oxidize or reduce the coloring matter, which is washed out to obtain permanent whiteness. Optical brighteners are added to the process in order to achieve higher whiteness levels

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