Changes in the Properties of Cotton Cellulose by Hydrogen Peroxide Bleaching

Abstract

The cotton contains various impurities such as protein, wax, pectins, coloring matter, even though cotton has been a major source of pure cellulose. The purification processes have been commonly applied to obtain the pure cellulose. However the excessive purification treatments could lead to the damage in the cellulose structure which could result in the degradation of cellulose and the limited application of cotton cellulose. In this study, the changes in cellulose structural properties such as crystallinity and DP(degree of polymerization) by the various conditions of the purification processes were investigated. The less toxic agents such as hydrogen peroxide and sodium silicate were applied for the purification treatment in this study. The increase in the process times, the temperature and the applied amount of chemical agents resulted in the more purified cellulose. The DP of cotton cellulose was increased at the first weak conditions by the reduction of small molecules such as pectin, wax, and so on. Especially the 2 % addition amount of H 2 O 2 with Na 2 SiO 3 resulted in the higher value in the DP and the brightness compared to the 1.5 % addition amount of H 2 O 2 . However, the 4 % addition amount of H 2 O 2 with Na 2 SiO 3 showed the decreased value because of excessive treatment. In case of the changes in the crystallinity (Gjk), the highest value of the crystallinity was obtained by the 2% addition amount of H 2 O 2 on the cotton cellulose, which showed similar with the change in the DP.

Effects of cultivation, washing, and bleaching conditions on bacterial cellulose fabric production

“…2,29 Crystallinity is known to be closely related to the chemical reactivity of cellulose. 7 The crystallinity of ''white BC fabric'' after the bleaching step was 80.6%, as shown in Table 3(c). This crystallinity is about 27% higher than that of ''production BC'' after the cultivation step (Table 3(a)).…”

“…Toxic substances, such as polychlorinated dioxin and furan, are detected in discharged water after bleaching with NaOCl. 6,7 Thus, hydrogen peroxide is used and its effectiveness in bleaching BC fabric without decreasing the fiber strength is evaluated. 6 In a previous study, Gea et al 5 reported a two-step BC purification process that involved washing with an NaOH solution and bleaching with an NaOCl solution.…”