Cellulose

About: Cellulose is a research topic. Over the lifetime, 59060 publications have been published within this topic receiving 1419643 citations. The topic is also known as: Hydroxycellulose & Pyrocellulose.

Pyrolysis Gas Chromatography Mass Spectrometry Studies to Evaluate High-Temperature Aqueous Pretreatment as a Way to Modify the Composition of Bio-Oil from Fast Pyrolysis of Wheat Straw

Abstract: Hot water pretreatment was systematically studied to determine whether reaction selectivity of cellulose toward the production of anhydrosugars and furanics could be improved. Samples of wheat straw and α-cellulose were treated using hot compressed water at temperatures ranging between 150 and 260 °C. The effect of hot water pretreatment on pyrolysis selectivity was measured using pyrolysis gas chromatography mass spectrometry (Py-GC/MS). Various representative peak area ratios were compared and used as an index of pyrolysis selectivity. The chemical and Py-GC/MS analysis of solid residues resulting from hot water pretreatment suggest that, as the temperature increased, the hemicelluloses and amorphous cellulose were solubilized. The relative areas of the Py-GC/MS results associated with levoglucosan increased for both straw and α-cellulose with increasing treatment temperature. The results show that the selectivity of thermochemical reactions toward the production of sugars and furanics can be enhanced i...

β-Glucan synthesis in the cotton fiber: II. Regulation and kinetic properties of β-glucan synthases

Abstract: The regulation and kinetic properties of cellulose synthase as well as [beta]-1,3-glucan synthase have been studied. The cellulose was detected using acetic/nitric acid insolubility as an indicator of cellulose (this product contained only [beta]-1,4-linked glucans; K. Okuda, L. Li, K. Kudlicka, S. Kuga, R.M. Brown, Jr. [1993] Plant Physiol 101: 1131–1142). These studies reveal that (a) [beta]-1,3-glucan synthesis is enhanced up to 31-fold by cellobiose with a Ka of 1.16 mM; (b) cellulose synthesis is increased 12-fold by a combination of cellobiose (Ka = 3.26 mM) and cyclic-3[prime]:5[prime]-GMP (Ka = 100 [mu]M); (c) the common components in the reaction mixture required by both enzymes are cellobiose, calcium, and digitonin; (d) cellulose synthase has an essential requirement for magnesium (Ka = 0.89 mM); (e) cellulose synthase also requires a low concentration of calcium (Ka = 90 [mu]M); (f) the optimal pH for cellulose synthase (7.6–8.0) is slightly higher than that for [beta]-1,3-glucan synthase (7.2–7.6); (g) the Km for UGP-Glc for cotton (Gossypium hirsutum) cellulose synthase is 0.40 mM; (h) the Km for UDP-Glc for for [beta]-1,3-glucan synthase is 0.43 mM.

Growth and Chemical Stability of Copper Nanostructures on Cellulosic Fibers

Abstract: The design of paper products based on copper nanoparticles (NPs) is a challenge because of the intrinsic propensity of Cu to oxidize in contact with air. Here, a comparative study on the growth and chemical stability of Cu NPs in vegetable and bacterial cellulose is described for the first time. Furthermore, comparative studies were performed by using inorganic fillers of distinct dimensionality, Cu NPs and Cu nanowires (NWs), in both types of cellulose. Cu NWs were found to be more resistant to oxidation caused by prolonged air exposure than the Cu NPs. Notably, the cellulosic matrices behave differently for the growth or adsorption of the Cu nanofillers; bacterial cellulose fibers are the most efficient substrate to delay surface oxidation. The data support a role for bacterial cellulose in limiting the oxidation of Cu nanostructures that have been grown or blended in this type of matrix, hence opening up new perspectives for the development of electronic paper technologies that incorporate copper nanophases.

Isolation and characterization of cellulosic fibers from kenaf bast using steam explosion and Fenton oxidation treatment

Abstract: Degumming is the dominant method to isolate cellulosic fibers in the textile industry. High content of lignin is the principle obstacle in bast-fibers degumming. In order to remove lignin efficiently, the treatment using steam explosion coupled with Fenton oxidation was conducted on kenaf bast in this study. The influence and mechanism of the combined treatment of steam explosion and Fenton oxidation were studied. Fiber microstructure, composition proportion and distribution, cellulose Segal crystallinity and polymerization as well as residual lignin structure were analyzed. The results showed that the pretreatment of steam explosion could sufficiently extract most of the hemicellulose from kenaf bast. Also, the Fenton oxidation followed by alkaline boiling could effectively remove the lignin from the fiber, especially from the fiber surface. The refined dry fibers produced only remained 8.82% of hemicellulose and 9.36% of lignin. And the whole treatment process didn’t change the cellulose crystalline structure but could gradually degrade hemicellulose, lignin and other amorphous gummy matter as well as disordered areas in cellulose, leading to the increase of fiber Segal crystallinity from 62.02 to 70.12%. Part of cellulose was damaged with the increase of degumming intensity, resulting in the decrease of the polymerization degree of cellulose. Meanwhile, the structure of residual lignin changed during the degumming stages of steam explosion, Fenton oxidation and alkaline boiling. All the results revealed that the treatment of combined steam explosion and Fenton oxidation is significantly effectual for isolating bast-fibers.