Analysis of the effects of catalytic bleaching on cotton

Abstract

Hydrogen peroxide can be catalyzed to bleach cotton fibers at temperatures as low as 308C by incorporating dinuclear tri-l-oxo bridged manganese(IV) complex of the ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (MnTACN) as the catalyst in the bleaching solution. The catalytic system was found to be more selective under the conditions applied than the non-catalytic H 2 O 2 system, showing better bleaching performance while causing slightly lower decrease in degree of polymerization (DP) of cellulose. In order to gain fundamental knowledge of the bleach effect on cotton fibers and cellulose as its main component, especially after catalytic bleaching, X-ray Photoelectron Spectroscopy (XPS) was used to study surface chemical effects. The Washburn method was applied to investigate wetting properties, and liquid porosity was used to obtain pore volume distribution (PVD) plots. Parallel analyzes performed on model cotton fabric, i.e. ''clean'' cotton fabric stained with morin -a pigment regularly found in native cotton fiber, helped to differentiate between pigment oxidation and other bleaching effects produced on the (regular) industrially scoured cotton fabric. Bleaching was not limited to the chemical action but also affected cotton fiber capillary parameters most likely due to the removal of non-cellulosic materials as well as chain-shortened cellulose.

Characterization of chars obtained from cellulose treated with phosphoramidate flame retardants

“…This amount mainly results from some minor nitrogen contamination in our chamber (blank measurements resulted in $ 0.5 at.% N; no other contaminations have been found) but can also be from leftover proteins on the surface of the cotton fibers (even after bleaching, pure cotton cellulose can still contain a surface concentration of non-cellulosic compounds (among them proteins), see Refs. [27,28]). The nitrogen concentration for the cotton cellulose treated with PAHEDE is enhanced, as expected due to nitrogen being part of the chemical structure of PAHEDE.…”

Structure and properties of silk fibroin modified cotton

“…XPS has been extensively used for the analysis of the composition of the outermost surface layers (analysis depth of a few nanometres) of fibers to our knowledge. The chemical shifts of carbon (C1s) in cotton fibers can usually be easily classified into four categories: unoxidized carbon (C-C), carbon with one oxygen bond (C-O), carbon with two oxygen bonds (O-C-O or C=O), and carbon with three oxygen bonds (O=C-O [24]). The relative amounts of carbons with different number bonds to oxygen were determined from carbon C1s spectra using peak-fitting into three symmetric Gaussian components.…”

Effect of TAED activated H2O2 bleaching on the properties and structure of jute fibers

“…The main purpose of bleaching is to remove colored matters and endow the material with a good whiteness [1]. Table I showed that the whiteness of jute could be significantly improved by using bleaching, and the whiteness value of TAED/H 2 O 2 system bleached jute was much more bigger than that of conventional H 2 O 2 bleached jute.…”

“…pigments [1]. Bleaching agents that are extensively utilized in the conventional bleaching process are chlorine and its derivatives owing to their high efficiency and low cost.…”

“…Unfortunately, conventional peroxide bleaching is typically conducted under conditions of high temperature (e.g. 95°C) and pH 11.5, such a harsh chemical treatment causes not only extensive consumption of energy but also can lead to a significant decrease in the degree of polymerization of cellulose [1,[4][5]. For these reasons, activated peroxide systems are desired to save energy and reduce fiber damage.…”