Abstract
Basic studies on a high temperature continuous bleaching of cotton sliver were made. Each 0.7g cotton sample was soaked in a 1-3% NaClO2 solution and centrifuged to a liquor ratio 1:1, which was placed in a small titanic autoclave and heated at 110-160°C for several minutes. After cooling, the undecomposed NaClO2 was titrated and the reflectance and DP of the bleached cotton were measured. The bleaching liquor was unbuffered and the pH decreased from 7 to 5. The results are:
(1) An apparent activation energy is obtained to 28.3kcal/mole for the NaClO2 decomposition reaction both in the cases of 1% and 3% solutions from the initial rate of NaClO2 decomposition; the degree of decomposition of NaClO2, e. i., the amount of the decomposed NaClO2 relative to the initial amount, of the 3% solution is larger than that of the 1% solution.
(2) The reflectance increases rapidly and levels off within 1 to 2min. at 140-160°C. An apparent activation energy of the bleaching reaction is 28.6kcal/mole and equal to the activation energy of the NaClO2 decomposition. The reflectance of the bleached cotton increases to 85, the maximum value, from 66, the reflectance of the unbleached cotton. The reflectance retrogrades uuder too severe conditions.
(3) The reflectance at the expense of equal amount of NaClO2 per g cotton is larger when 1% solution is used than when 3% solution is used.
