Search

This work focuses on the influence of ozone pretreatment on the fractionation and solubilization of sugarcane bagasse and soda bagasse pulp fibers in sodium hydroxide/urea solution, as well as the application of regenerated cellulose for producing edible films. The methodology involved pretreating lignocelluloses with ozone for 20 to 120 min before dissolving in sodium hydroxide/urea solution. The influence of the pretreatment conditions on cellulose dissolution yield was investigated. Regenerated cellulose films were then formed, with and without the addition of 2 % chitosan. Mechanical, physical, structural, thermal, and antimicrobial attributes were determined as a function of ozonation conditions of raw materials and chitosan content. The findings exhibited positive effects of short ozonation on enhancing mechanical strength, cohesion, and hydrophobicity. The prolonged ozonation of 120 min demonstrated optimal improvements in continuity, swelling, and antibacterial resistance of obtained films. Incorporating chitosan enhanced tensile performance, stiffness, and vapor barriers but increased moisture absorption. Tailoring the activation of biomass through ozone pretreatment and chitosan addition resulted in renewable films with adjustable properties to meet diverse packaging requirements, particularly for fruit protective coatings, ensuring the preservation of post-harvest quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microfibrillated cellulose (MFC) is an emerging cellulosic material that has shown enormous potential in various industrial sectors such as food packaging, cosmetics, pharmaceuticals, filler for cement and paper, and others. Yet, there is still the need to improve its processing in order to reach its full potential. Despite research efforts for the production of MFC, the production volumes remain low because the costs of these products are hardly competitive with synthetic polymers. The present study investigates the conversion of bleached Kraft pulp into MFC using three different oxidative treatments: (1) oxidation with sodium periodate followed by oxidation with hydrogen peroxide to enrich the pulp with carboxyl groups; (2) activation of hydrogen peroxide with copper to produce hydroxyl radicals; and (3) use of hydrogen peroxide alone in alkaline medium. Treatments (1) and (2) allowed producing interesting MFC with reduced energy consumption., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

The aim of the present study is to investigate the dissolving ability of a cellulosic substrate using a derivatization method, i.e. cellulose tricarbanilation and the follow-up by dynamic light scattering (DLS), for particle size measurement. The dissolving behavior of six commercial pulps, selected for their different nature and properties, were compared to the Fock test, and the analysis was completed by other methods for substrate characterization: crystallinity (XRD), DPv (in CuED), sugar analysis, molecular weight distribution (MWD) of cellulose by HPSEC-multidetectors (done on the cellulose tricarbanilates), and solubility in NaOH:urea:water. The proposed carbanilation/DLS method resulted practical and suitable for evaluating the dissolving ability of the different pulps – including hemicelluloses-containing kraft pulps – and allowed to discriminate the samples, contrary to the Fock test. Comparison and assessment of the relevance of the different methods are finally discussed. [ABSTRACT FROM AUTHOR]

A cold holocellulose treatment (cHolT) was studied on a bleached kraft pulp (BKP) of Eucalyptus to observe the degradation of polysaccharides in pulp by chlorite at room temperature under conditions of slightly acidic pH and high chlorine charge (313% of active chlorine on BKP). Based on literature data, cellulose depolymerization is expectable by chlorite treatments at 70°C and reinforced chlorite charge, while the addition of dissolved lignin could protect cellulose. In the present study, polysaccharide degradation was followed by TAPPI viscosity, size-exclusion chromatography coupled to multidetectors, pulp yield, kappa number, elemental sugar analysis of pulps, and total organic carbon detection in filtrates. cHolTs were repeated several times without significant polysaccharide degradation, but the insertion of a caustic extraction stage at 70°C induced little degradation. This study opens the way to the setup of inert delignification procedures to be applied on raw or processed lignocellulosic samples from biorefinery studies. [ABSTRACT FROM AUTHOR]

Recovered fibers are reused for manufacturing bright paper after deinking and fiber decolorization. This second process generally starts with an alkaline hydrogen peroxide (H2O2) stage, referred to as P. However, the color-stripping effect of P is often limited due to the low reactivity of H2O2 on the azo groups of dyes. The purpose of this study was to improve the removal of these azo dyes by H2O2. A bleached kraft pulp was dyed with a model azo dye and submitted to activated H2O2 bleaching. Phenanthroline and copper(II)-phenanthroline (Cu-Phen) served as activating compounds. The color-stripping trials were carried out at weak or conventional alkaline pH. The results were mainly evaluated in terms of dye removal index and degree of polymerization of cellulose. The theoretical composition of Cu-Phen in the bleaching conditions was calculated by means of the geochemical software PHREEQC. The results show that Cu-Phen was able to activate H2O2 color stripping, although it was accompanied by additional cellulose degradation. Moreover, the color stripping was more effective under alkaline conditions, in which case CuPhen(OH)2 would be present. Two hypotheses are proposed to explain this activated decolorization: a free radical mechanism and the influence of CuPhen(OH)2 as an activating species. [ABSTRACT FROM AUTHOR]

The ClO2 titration method for in situ measurement of free phenolic groups in pulp has been improved to minimize interferences from other groups susceptible to react with ClO2. The method is based upon the reaction between free phenolic groups and chlorine dioxide at a temperature of 0°C, in the presence of dimethyl sulfoxide. Theoretically, one free phenolic group consumes two molecules of ClO2. The pH of the ClO2 treatment was advantageously fixed at 6.7 using a phosphate buffer, and a new protocol was proposed to avoid any possible interference of quinone groups (either present in pulp or formed during the procedure) on the residual ClO2 titration step. The results obtained on isolated lignin samples were compared to those measured by 31P NMR spectroscopy. The ClO2 method gave substantially higher values, for reasons which deserve further investigation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pure cellulose was produced from a hardwood Kraft pulp. [•] A totally chlorine-free process was applied on the unbleached pulp. [•] Hydrogen peroxide delignification catalyzed by copper phenanthroline was applied. [•] Cold caustic extraction and ozonation were used to complete the process. [•] The bleached cellulose exhibits the quality of a dissolving pulp. [ABSTRACT FROM AUTHOR]