Color and Color Reversion of Cellulosic and Lignocellulosic Fibers

Castellan, Alain; Grelier, Stéphane

doi:10.1002/9781118773727.ch21

Cited by 4 publications

(4 citation statements)

References 67 publications

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“…Thus, α‐cellulose was less bright than cellulose‐EFB. Pulp brightness depended inversely on yellowness, 46 which is in keeping with the results in Table 3.…”

Section: Resultssupporting

confidence: 87%

“…A whiteness index quantifies how closely a surface mimics a perfect reflecting diffuser, i.e., a surface that neither absorbs nor transmits light, but reflects it equally in all directions. Development of yellowness is generally associated with product degradation 45,46 . A yellowness index is a measure of how much the color of a surface is shifted towards yellow from the preferred white, or colorless.…”

Section: Resultsmentioning

confidence: 99%

“…A lower brightness of α‐cellulose compared to cellulose‐EFB was unexpected, as the former was free of lignin (the section entitled ‘TGA and FTIR’ details the evidence based on FTIR spectral data). Reversion of brightness (i.e., development of yellowness) may be explained at least partly by oxidation of carbohydrates in the sample, in addition to other possible causes 46 . The alkali used (17.5% NaOH) for producing α‐cellulose from cellulose‐EFB was equivalent to nearly 5.3 M NaOH, whereas a much lower concentration (e.g., 1 M at 22 °C) can produce noticeable oxidation of carbohydrate monomers of cellulose 47 .…”

Section: Resultsmentioning

confidence: 99%

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Cellulose from oil palm empty fruit bunch fiber and its conversion to carboxymethylcellulose

Yimlamai

Choorit

Chisti

et al. 2021

J of Chemical Tech & Biotech

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BACKGROUND Higher‐value products, such as cellulose and carboxymethylcellulose (CMC), may be produced from lignocellulosic agroindustrial residues, such as oil palm empty fruit bunch (EFB) fibers that are presently underutilized or discarded. Recovery of cellulose from EFB and its conversion of CMC are discussed as methods of creating value and reducing the environmental impact of EFB. RESULTS Cellulose was recovered from EFB fibers and converted to water soluble CMC. Cellulose isolation used a two‐step sequential treatment involving peracetic acid (PA) (50 g dry EFB L−1 PA, 35 °C, 9 h) for initial delignification, and then alkaline peroxide (AP) (50 g delignified‐EFB L−1 AP, 45 °C, 12 h). This treatment removed 91.5% of lignin in the original EFB fiber. The recovered solids, designated as cellulose‐EFB, were comprised of 83.7 ± 3.4% cellulose, 5.6 ± 0.3% hemicellulose, 1.7 ± 0.0% lignin, and 1.7 ± 0.1% ash. A two‐step process with an initial alkalization {3 g cellulose‐EFB in 99 mL solvent [10:1 by vol mixture of ethanol (95%) and 35% NaOH], 30 °C, 2 h} followed by etherification was used to convert cellulose‐EFB to CMC sodium salt. The conversion yield was 50% of the theoretical maximum. CONCLUSION The best conditions for preparing CMC from cellulose‐EFB were a 2 h treatment with 35% (wt/vol) NaOH during alkalization at 30 °C, followed by etherification at 55 °C. The CMC had a degree of substitution of 0.16 and a water solubility of 6.8 g L−1 at 30 °C. © 2021 Society of Chemical Industry

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“…Thus, α‐cellulose was less bright than cellulose‐EFB. Pulp brightness depended inversely on yellowness, 46 which is in keeping with the results in Table 3.…”

Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Cellulose from oil palm empty fruit bunch fiber and its conversion to carboxymethylcellulose

Yimlamai

Choorit

Chisti

et al. 2021

J of Chemical Tech & Biotech

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“…It was proved previously that alkaline medium facilitates lignin degradation and that some deacidification treatments induced yellowing of ground wood paper [48]. Alkaline darkening of some high-yield pulps was caused by the formation of o-quinones and coniferaldehydes [49]. Unreported additives might also be present in the commercial deacidification dispersions which could additionally induce color changes.…”

Section: Effect On the Paper Colormentioning

confidence: 93%

Nano calcium carbonate versus nano calcium hydroxide in alcohols as a deacidification medium for lignocellulosic paper

et al. 2019

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Deacidification is an established conservation treatment for the prolongation of the acidic paper stability. Several different deacidification systems are in use today, such as the dispersions of alkaline nanoparticles in organic solvents. The aim of the study was to compare the effects of different calcium nanoparticle dispersions in alcohols on lignocellulosic paper. Commercially available nano calcium hydroxide dispersions for paper deacidification, and laboratory prepared nano calcium carbonate dispersions in ethanol and 2-propanol were investigated and compared as to their effectiveness in increasing the stability of paper. The FE-SEM analyses were used to determine the size of Ca(OH) 2 and CaCO 3 particles in the dispersions. The SEM-EDS analyses were performed both on the paper surface and its crosssection in order to ascertain the distribution of calcium ions following the deacidification treatment. An evaluation of the changes of color, molecular weight, pH and alkaline reserve on different lignocellulosic papers was performed. In comparison to untreated samples, our results indicate all the investigated deacidification treatments decrease the degradation rate constant of cellulose, as determined by accelerated degradation. However, the treatments involving nano calcium hydroxides in both alcohols noticeably affect the color of the treated lignocellulosic papers. According to the obtained results, nano calcium carbonate is therefore the more suitable deacidification agent for the lignin containing papers.

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