Oxidative Degradation Of Cellulose Research Articles

Comparison of Aqueous and Non‐Aqueous Treatments of Cellulose to Reduce Copper‐Catalyzed Oxidation Processes

AbstractSummary. The present paper examines oxidative degradation of cellulose catalyzed by presence of Cu1+and Cu2+ ions in the context of historic paper conservation treatments. Aqueous treatments of degraded papers further spread transition metal ions, such as copper, across the fibre matrix, and therefore augment the detrimental effect of these ions. In the paper industry, the inhibiting effects of magnesium ions on metal‐catalyzed degradation of cellulose contaminated with metal impurities have been observed. Also, magnesium compounds dissolved in alcoholic or aqueous solutions are generally used in paper conservation as deacidification agents. Paper samples with artificially produced copper corrosion served as mock‐ups for examination and comparison of different treatments which focused on the inhibiting effect of magnesium and antioxidants. Analytical examination of molecular weight distribution, carbonyl content, carboxyl content, and surface pH was performed. Results show an inhibiting effect of magnesium on copper‐catalyzed cellulose degradation, although less pronounced than expected.

Oxidative cellulose degradation by cellobiose dehydrogenase from Phanerochaete chrysosporium: A model compound study

AbstractCellobiose dehydrogenase (CDH) is an extracellular enzyme produced by various wood-degrading fungi. It oxidizes cellobiose to cellobionolactone under reduction of molecular oxygen to hydrogen peroxide, and Fe3+to Fe2+. These activated agents can thereafter form highly reactive hydroxyl radicals, which depolymerize wood polymers. In this work, cellulose depolymerization by CDH was studied using a model compound, methyl β-D-glucopyranoside. The formation of glucose, arabinose, gluconic acid, erythrulose and formaldehyde were detected and a mechanism for the reaction is proposed. The biological importance of this enzyme-initiated reaction is discussed.

Photo-induced degradation of cellulose

Irradiation by light is considered to be one of the primary sources of damage exerted upon cellulosic substrates at ambient conditions. Yet, contrary to studies on thermal ageing of cellulose, only limited attention is devoted to light induced degradation of paper. This research demonstrates that extensive oxidative degradation of cellulose, accompanied by formation of hydroxyl radicals, occurs during exposure to light with λ > 340 nm. As demonstrated by size exclusion chromatography, degradation is not random. No high-molecular weight fraction appears in the irradiated sample, meaning that cross-linking is not a dominant process. This justifies the use of viscometry for light-irradiated cellulosic materials. Studies show that the rate of degradation, carbonyl formation and brightness decrease may be reduced by addition of magnesium carbonate.

The effect of metal ions on thermal oxidative degradation of cotton cellulose ammonium phosphate

The thermal oxidative degradation of cellulose, and of cellulose ammonium phosphate and its metal complexes products were studied by thermal analysis, infrared spectroscopy and elemental analysis. The temperature of decomposition was lower for metal complexes of cellulose ammonium phosphate than those samples untreated by metal ions and the values of char yield were greater for treated cellulose than those untreated. This indicates the metal ions can catalyze the reaction of degradation and form more char.

FT-IR and FT-Raman study of hydrothermally degraded groundwood containing paper

Accelerated aging test of paper is used to understand mechanisms of acidic hydrolysis and oxidative degradation of cellulose, hemicellulose and lignin. In recent years FT-IR and FT-Raman spectroscopy have been used together with mass spectrometry and nuclear magnetic resonance as well as chemometrics methods to characterize degradation products of paper. In this work we present FT-IR and FT-Raman spectra of hydrothermally treated sample of acid paper (Paper 3—bleached sulfite softwood pulp) in extreme humid conditions (100% humidity and 100 °C). Degradation reaction is monitored mainly based on CO stretching vibrations formed during the process of carbonyl compounds, however, some changes in CC stretching vibrations are also noticed. We showed that in these conditions paper undergoes oxidation process in which at least three new carbonyl species that can be characterized by their CO stretches are formed. Additionally, during this process, one can observe disappearance of the CC stretching that can be associated with changes that involve, for example, coniferyl alcohol. We also show that water molecules play very important role in this process. Thus, we report here, changes caused by hydrothermal treatment of groundwood containing paper mainly associated with the appearance of new carbonyl species, besides others, as well as rearrangement of existing hydrogen bond network.

A peptide-mediated and hydroxyl radical HO*-involved oxidative degradation of cellulose by brown-rot fungi.

A special low-molecular-weight peptide named Gt factor, was isolated and purified from the extracellular culture of brown-rot fungi Gloeophyllum trabeum via gel filtration chromatography and HPLC. It has been shown to reduce Fe3+ to Fe2+. Electron paramagnetic resonance (EPR) spectroscopy revealed Gt factor was able to drive H2O2 generation via a superoxide anion O2*- intermediate and mediate the formation of hydroxyl radical HO* in the presence of O2. All the results indicated that Gt factor could oxidize the cellulose, disrupt the inter- and intrahydrogen bonds in cellulose chains by a HO*-involved mechanism. This resulted in depolymerization of the cellulose, which made it accessible for further enzymatic hydrolysis.

Some preventive cellulose antioxidants studied by an aromatic hydroxylation assay

Since the oxidative degradation of cellulose is enhanced in the presence of ferric compounds, the N,N′-(5-nitro,1,3-phenylene)bisglutaramide hydroxylation assay was used to test the efficiency of possible preventive antioxidants: EDTA, DTPA, citrate, desferrioxamine methanesulphonate (desferal) and phytate. The corresponding rate constants and apparent activation energies for hydroxyl radical production in the aqueous systems in the pH interval 6.5–8 were obtained. The rate constants were correlated with the decrease of degree of polymerisation of artificially aged cellulose samples enriched with CaCO 3 and iron in the form of the corresponding complex ( R=0.9891). It is concluded that the catalytic role of iron is similar in both systems and that the hydroxylation assay may provide valuable estimations of the degradation rates of cellulosic materials in the conditions of use. The chelating compounds shown to have an antioxidant effect at 20 °C in the pH interval studied are DTPA, phytate, and desferal, in the order of increasing positive effect.

Smolder of Cellulosic Fabrics. II. Water, Alkali and Inner Oxygen as Variables

Pyrolysis and oxidative decomposition of cellulosic fabric were studied. Alkali metal compounds were found to be essential for sustaining smol dering and to promote oxidative degradation of cellulose and assist cleavage of sugars only in the presence of water. Decomposition activity of cellulose de creased with dehydration. Study of temperature programmed reactions (TPR) in He suggested the production of COx via intermediate oxygen-containing com pounds. Intramolecular redox reactions below 300°C were suggested to explain the formation of a part of CO2. Peroxide groups were found in #6 cotton duck fab ric. They may be responsible for oxidative decomposition of cellulose around 200°C. Two peaks of COx formation rate, obtained from TPR experiments, were attributed to intramolecular redox reaction, followed by decarboxylation, and ox idation of carbohydrates by residual bound oxygen. Water washing may increase the fabric/gas permeability.

The kinetics of the oxidative degradation of cellulose and cellulose doped with chlorides

The kinetic parameters of the thermal decomposition in air of pure α-cellulose and the same cellulose impregnated with calcium chloride, potassium chloride, sodium chloride and zinc chloride have been obtained using an isothermal mass loss method. The results from these experiments can be shown to agree closely with kinetic parameters obtained by other workers using a variety of techniques for the pyrolytic degradation of cellulose. It can be shown that the introduction of each chloride produces a different kinetic behavior as identified by the form of the mass loss curves corresponding to the various theoretical kinetic models. A compensation plot is observed relating the logarithm of the pre-exponential term with the activation energy. It is thought that the activation energies reported here may be associated predominantly with the formation of carbon monoxide and carbon dioxide.

Catalyst-assisted oxidative cellulose degradation in an alkaline medium

Catalyst-assisted oxidative cellulose degradation in an alkaline medium

Mechanism of the oxidative degradation of cellulose in alkaline media—II. Mechanism of the oxidation of cellulose in an alkaline medium by oxygen

Mechanism of the oxidative degradation of cellulose in alkaline media—II. Mechanism of the oxidation of cellulose in an alkaline medium by oxygen

A Non-enzymatic Oxidative Degradation of Cellulose occurring in Preserved Cabbage Tissue

IT is recognized that plant materials preserved in dilute acetic acid exhibit a slow loss of tissue strength as a result of the structural components undergoing hydrolysis. This is caused either directly by the low pH of the medium, or indirectly from the presence of hydrolytic enzymes secreted by micro-organisms previously associated with the tissue1. An additional form of tissue breakdown, which has not apparently attracted previous attention, has been observed in the work recorded here. This is in no way connected with microbial action, and is oxidative in character.

塩素水溶液による木材セルロースの不均一系酸化崩壊

塩素水溶液による木材セルロースの不均一系酸化崩壊

パルプのハイポクロライト漂白に際してセルロースの酸化崩壊に及ぼすヘミセルロースの影響

パルプのハイポクロライト漂白に際してセルロースの酸化崩壊に及ぼすヘミセルロースの影響

Investigation upon Dissolving Pulp

Rayon grade sulfite pulp (RP, α-cellulose 92%), acetate grade sulfite pulp (ACP, α-cellulose 96%) and purified linters (Linters, α-cellulose 99%) were oxidized by ClO2 solution under the following condition : ClO2 (as avail. cl.) add. : 0-40% basis B. D. pulp, temp : 70°C, initial PH : 3-11 (unbuffered), and average D P, copper number, carboxyl content, brightness, methoxyl content and also U. V. absorption spectrum of these treated pulps in ca. 80% H3 PO4 have been determined. The results areas follows : 1. With RP, the rate of oxidative degradation of cellulose by ClO2 solution is very mild, with consequence of selective dissolution of residual lignin without affecting any influence upon functional groups (e. g. carboxyl, carbonyl groups). However, under the presence of extremely high amount of ClO2 in the range of PH (initial) 7 or more, the degradation of cellulose also progressed gradually, 2. On the other hand, linters and ACP are very susceptible to the oxidation by C1O2 and are apt to suffer from appreciable degradation, with consequence of decrease in a-cellulose, Cu-NH3 viscosity, and increase in copper number and carboxyl content.3. From these results it has been found that the noncellulosic material such as lignin and especially hemicellulose associated with cellulose has the protective action against the heterogeneous degradation of cellulose by ClO2 solution. This phenomenon could be explained by preferential consumption of oxidizing agent by noncellulosic material. With this point, further discussion will be published in next report.4. It has been found that the oxidized cellulose and hemicellulose have characteristic U.V. absorption spectrum near 290mμ.

Chemical transformations of cellulose macromolecules caused by oxidants Part 7. Chemical transformations of cellulose due to its oxidation with sodium hypochlorite

1. Chemical changes in the structure of cotton cellulose due to oxidation with sodium hypochlorite at different pH have been investigated by means of specific quantitative micromethods. 2. The following groups have been found in the oxycellulose obtained by hypochlorite oxidation: uronic and non-uronic carboxylic groups, C8 aldehydic groups,α-hydroketonic and lactone groups, and carbonic acid ester (ether) groupings. 3. The oxycelluloses obtained by oxidation in acid and neutral solution have a similar structure, different from that obtained in alkaline solution. 4. A reaction mechanism is advanced for the oxidative degradation of cellulose by action of sodium hypochlorite at various pH. This mechanism satisfactorily explains the chemical behaviour of the oxidation products. 5. The various oxidative processes shown to occur may be utilized for the better control of such processes, and for the preparation of cellulose oxidation products of known properties.