Polymers

Research

21 pages, 21678 KiB

Open AccessArticle

The Interplay of Autoclaving with Oxalate as Pretreatment Technique in the View of Bioethanol Production Based on Corn Stover

by Ali Hamdy, Sara Abd Elhafez, Hesham Hamad and Rehab Ali

Polymers 2021, 13(21), 3762; https://doi.org/10.3390/polym13213762 - 30 Oct 2021

Cited by 9 | Viewed by 1981

Abstract

Bio-based treatment technologies are gaining great interest worldwide, and significant efforts are being afforded to develop technology for the use of lignocellulosic biomass. The potential of corn stover (CS) as a feedstock for bioethanol production was investigated by creating an optimal pretreatment condition [...] Read more.

Bio-based treatment technologies are gaining great interest worldwide, and significant efforts are being afforded to develop technology for the use of lignocellulosic biomass. The potential of corn stover (CS) as a feedstock for bioethanol production was investigated by creating an optimal pretreatment condition to maximize glucose production. The current study undertook the impact of novel physico-chemical pretreatment methods of CS, i.e., autoclave-assisted oxalate (CSOA) and ultrasound-assisted oxalate (CSOU), on the chemical composition of CS and subsequent saccharification and fermentation for bioethanol production. The delignification was monitored by physicochemical characterizations such as SEM, XRD, FTIR, CHNs, and TGA. The results evidenced that delignification and enzymatic saccharification of the CS pretreated by CSOA was higher than CSOU. The optimum enzymatic saccharification operating conditions were 1:30 g solid substrate/mL sodium acetate buffer at 50 °C, shaking speed 100 rpm, and 0.4 g enzyme dosage. This condition was applied to produce glucose from CS, followed by bioethanol production by S. cerevisiae using an anaerobic fermentation process after 72 h. S. cerevisiae showed high conversion efficiency by producing a 360 mg/dL bioethanol yield, which is considered 94.11% of the theoretical ethanol yield. Furthermore, this research provides a potential path for waste material beneficiation, such as through utilizing CS. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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10 pages, 1956 KiB

Open AccessArticle

Oxidative Depolymerization of Alkaline Lignin from Pinus Pinaster by Oxygen and Air for Value-Added Bio-Sourced Synthons

by Martin Camus, Olivia Condassamy, Frédérique Ham-Pichavant, Christelle Michaud, Sergio Mastroianni, Gérard Mignani, Etienne Grau, Henri Cramail and Stéphane Grelier

Polymers 2021, 13(21), 3725; https://doi.org/10.3390/polym13213725 - 28 Oct 2021

Cited by 3 | Viewed by 1725

Abstract

In this work, an efficient 3-step process targeting the chemical modification and purification of lignin oligomers from industrial alkaline lignin is described. The oxidative depolymerization process of alkaline lignin with O₂ or Air pressure, without use of metal catalyst, led to the [...] Read more.

In this work, an efficient 3-step process targeting the chemical modification and purification of lignin oligomers from industrial alkaline lignin is described. The oxidative depolymerization process of alkaline lignin with O₂ or Air pressure, without use of metal catalyst, led to the production of two fractions of lignin oligomers named ‘precipitated lignin’ and ‘hydrosoluble lignin’ with 40% and 60% yield, respectively. These fractions were characterized with a wide range of methods including NMR spectroscopy (31P, 2D-HSQC), SEC (in basic media), FTIR. NMR analyses revealed the presence of carboxylic acid functions at a ratio of 1.80 mmol/g and 2.80 mmol/g for the precipitated and hydrosoluble lignin, respectively, values much higher than what is generally found in native lignin (between 0.2 and 0.5 mmol/g). SEC analyses revealed the formation of low molar masses for the precipitated (2200 g/mol) and hydrosoluble fractions (1500 g/mol) in contrast to the alkaline lignin (3900 g/mol). It is worth noting that the hydrosoluble fraction of lignin is soluble in water at any pH. Both processes (oxygen and air) were successfully scaled up and showed similar results in terms of yield and functionalization. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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14 pages, 3662 KiB

Open AccessArticle

Cellulose-Based Films with Ultraviolet Shielding Performance Prepared Directly from Waste Corrugated Pulp

by Guangmei Xia, Qiwen Zhou, Zhen Xu, Jinming Zhang, Xingxiang Ji, Jun Zhang, Haq Nawaz, Jie Wang and Jianfeng Peng

Polymers 2021, 13(19), 3359; https://doi.org/10.3390/polym13193359 - 30 Sep 2021

Cited by 14 | Viewed by 3036

Abstract

As the most important paper packaging materials, corrugated cartons with a tremendous amount of production demonstrate several advantages and have been widely used in daily life. However, waste corrugated cartons (WCCs) are usually recycled and reused to produce new corrugated cartons, and their [...] Read more.

As the most important paper packaging materials, corrugated cartons with a tremendous amount of production demonstrate several advantages and have been widely used in daily life. However, waste corrugated cartons (WCCs) are usually recycled and reused to produce new corrugated cartons, and their properties are decreased dramatically after several cycles. Therefore, recycling and converting WCCs into cellulose-based film with high value is attractive and significant. Herein, without any pretreatment, the waste old corrugated cartons were directly dissolved in ionic liquid 1-allyl-3-methylimidazolium chloride, and semitransparent cellulose-based films were successfully fabricated. It was indicated that cellulose-based films displayed better UV-shielding property and hydrophobicity than traditional cellulose films. Interestingly, the cellulose-based films regenerated from deionized water displayed higher tensile strength, elongation at break, and toughness. Their tensile strength could reach 23.16 MPa, exhibiting enormous superiority as wrapping and packaging materials to replace the petrochemical polyethylene membrane (8.95 MPa). Consequently, these renewable, biodegradable, and high-valued cellulose-based films were successfully fabricated to simultaneously realize the valorization of old corrugated cartons and supplement the petrochemical plastics. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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11 pages, 976 KiB

Open AccessArticle

Impact of the Enzyme Charge on the Production and Morphological Features of Cellulose Nanofibrils

by Sergio Henríquez-Gallegos, Gregory Albornoz-Palma, Andrea Andrade, Carolina Soto and Miguel Pereira

Polymers 2021, 13(19), 3238; https://doi.org/10.3390/polym13193238 - 24 Sep 2021

Cited by 10 | Viewed by 1593

Abstract

The available research does not allow specific relationships to be established between the applied enzymatic-mechanical treatment, the degree of polymerization, and the characteristics of the cellulose nanofibrils (CNFs) produced. This work aims to establish specific relationships between the intensity of enzymatic treatment, the [...] Read more.

The available research does not allow specific relationships to be established between the applied enzymatic-mechanical treatment, the degree of polymerization, and the characteristics of the cellulose nanofibrils (CNFs) produced. This work aims to establish specific relationships between the intensity of enzymatic treatment, the degree of polymerization of the cellulose, the morphology of CNFs, and the tensile strength of the CNF films. It is determined that the decrease in the degree of polymerization plays an essential role in the fibrillation processes of the cell wall to produce CNFs and that there is a linear relationship between the degree of polymerization and the length of CNFs, which is independent of the type of enzyme, enzyme charge, and intensity of the applied mechanical treatment. In addition, it is determined that the percentage of the decrease in the degree of polymerization of CNFs due to mechanical treatment is irrespective of the applied enzyme charge. Finally, it is shown that the aspect ratio is a good indicator of the efficiency of the fibrillation process, and is directly related to the mechanical properties of CNF films. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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15 pages, 2865 KiB

Open AccessArticle

Lignin-Containing Coatings for Packaging Materials—Pilot Trials

by Asif Javed, Peter Rättö, Lars Järnström and Henrik Ullsten

Polymers 2021, 13(10), 1595; https://doi.org/10.3390/polym13101595 - 15 May 2021

Cited by 5 | Viewed by 2701

Abstract

One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. [...] Read more.

One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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13 pages, 2901 KiB

Open AccessArticle

Rapid Benzylation of Wood Powder without Heating

by Mitsuru Abe, Masako Seki, Tsunehisa Miki and Masakazu Nishida

Polymers 2021, 13(7), 1118; https://doi.org/10.3390/polym13071118 - 1 Apr 2021

Cited by 5 | Viewed by 1896

Abstract

Converting wood waste into thermoplastic materials is an attractive means of increasing its utilization. A promising method for imparting thermoplasticity to wood is chemical modification, in which the hydroxyl groups in wood are substituted with benzyl groups. In the common method, wood powder [...] Read more.

Converting wood waste into thermoplastic materials is an attractive means of increasing its utilization. A promising method for imparting thermoplasticity to wood is chemical modification, in which the hydroxyl groups in wood are substituted with benzyl groups. In the common method, wood powder is first treated with a highly concentrated aqueous NaOH solution, and then reacted with a benzylation reagent by heating for a long time under stirring. In this study, a 50% aqueous tetra-n-butylphosphonium hydroxide solution was used for the pretreatment of wood powder. This modified alkaline treatment enhanced the efficiency of the subsequent benzylation reaction, which could be conducted without heating over a shorter time. The effects of various conditions on the efficiency of the benzylation reaction were evaluated. Both the alkali pretreatment and the subsequent benzylation required only ~5–10 min of stirring without heating to obtain benzylated wood with a similar degree of benzylation as that achieved by the common method. The chemical structure of the benzylated wood powder was characterized by Fourier-transform infrared and solid-state NMR spectroscopies, and its thermal softening characteristics were evaluated by thermomechanical analysis. Finally, a translucent film could be obtained by hot-pressing the benzylated wood powder. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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17 pages, 4846 KiB

Open AccessArticle

Monovalent Salt and pH-Induced Gelation of Oxidised Cellulose Nanofibrils and Starch Networks: Combining Rheology and Small-Angle X-ray Scattering

by Kazi M. Zakir Hossain, Vincenzo Calabrese, Marcelo A. da Silva, Saffron J. Bryant, Julien Schmitt, Jennifer H. Ahn-Jarvis, Frederick J. Warren, Yaroslav Z. Khimyak, Janet L. Scott and Karen J. Edler

Polymers 2021, 13(6), 951; https://doi.org/10.3390/polym13060951 - 19 Mar 2021

Cited by 4 | Viewed by 2737

Abstract

Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised [...] Read more.

Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Addition of NaCl caused an increased stiffness of the OCNF:starch (1:1 wt%) blend gels, where salt played an important role in reducing the repulsive OCNF fibrillar interactions. The rheological properties of these hydrogels were unchanged at pH 5.0 to 9.0. However, at lower pH (4.0), the stiffness and viscosity of the OCNF and OCNF:starch gels appeared to increase due to proton-induced fibrillar interactions. In contrast, at higher pH (11.5), syneresis was observed due to the formation of denser and aggregated gel networks. Interactions as well as aggregation behaviour of these hydrogels were explored via ζ-potential measurements. Furthermore, the nanostructure of the OCNF gels was probed using small-angle X-ray scattering (SAXS), where the SAXS patterns showed an increase of slope in the low-q region with increasing salt concentration arising from aggregation due to the screening of the surface charge of the fibrils. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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13 pages, 2226 KiB

Open AccessArticle

Enhancing Lignin Dissolution and Extraction: The Effect of Surfactants

by Elodie Melro, Artur J. M. Valente, Filipe E. Antunes, Anabela Romano and Bruno Medronho

Polymers 2021, 13(5), 714; https://doi.org/10.3390/polym13050714 - 26 Feb 2021

Cited by 9 | Viewed by 2942

Abstract

The dissolution and extraction of lignin from biomass represents a great challenge due to the complex structure of this natural phenolic biopolymer. In this work, several surfactants (i.e., non-ionic, anionic, and cationic) were used as additives to enhance the dissolution efficiency of model [...] Read more.

The dissolution and extraction of lignin from biomass represents a great challenge due to the complex structure of this natural phenolic biopolymer. In this work, several surfactants (i.e., non-ionic, anionic, and cationic) were used as additives to enhance the dissolution efficiency of model lignin (kraft) and to boost lignin extraction from pine sawdust residues. To the best of our knowledge, cationic surfactants have never been systematically used for lignin dissolution. It was found that ca. 20 wt.% of kraft lignin is completely solubilized using 1 mol L⁻¹ octyltrimethylammonium bromide aqueous solution. A remarkable dissolution efficiency was also obtained using 0.5 mol L⁻¹ polysorbate 20. Furthermore, all surfactants used increased the lignin extraction with formic acid, even at low concentrations, such as 0.01 and 0.1 mol L⁻¹. Higher concentrations of cationic surfactants improve the extraction yield but the purity of extracted lignin decreases. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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10 pages, 2992 KiB

Open AccessCommunication

On the Development of All-Cellulose Capsules by Vesicle-Templated Layer-by-Layer Assembly

by Alireza Eivazi, Bruno Medronho, Björn Lindman and Magnus Norgren

Polymers 2021, 13(4), 589; https://doi.org/10.3390/polym13040589 - 16 Feb 2021

Cited by 8 | Viewed by 2945

Abstract

Polymeric multilayer capsules formed by the Layer-by-Layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating [...] Read more.

Polymeric multilayer capsules formed by the Layer-by-Layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating two cellulose derivatives, anionic carboxymethylcellulose (CMC), and cationic quaternized hydroxyethylcellulose ethoxylate (QHECE), onto a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB). The obtained capsules were characterized by dynamic light scattering (DLS), ζ potential measurements, and high-resolution scanning electron microscopy (HR-SEM). DLS measurements reveal that the size of the particles can be tuned from a hundred nanometers with a low polydispersity index (deposition of 2 layers) up to micrometer scale (deposition of 6 layers). Upon the deposition of each cellulose derivative, the particle charge is reversed, and pH is observed to considerably affect the process thus demonstrating the electrostatic driving force for LbL deposition. The HR-SEM characterization suggests that the shape of the core-shell particles formed is reminiscent of the spherical vesicle template. The development of biobased nano- and micro-containers by the alternating deposition of oppositely charged cellulose derivatives onto a vesicle template offers several advantages, such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over particle size and composition of the shell. Full article

(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)

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