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14 pages, 3075 KiB

Open AccessArticle

Lignin Degradation via Chlorine Dioxide at Room Temperature: Chemical Groups and Structural Characterization

by Shuxian Weng, Guixin Zhang, Yun Hu, Caiying Bo, Fei Song, Guodong Feng, Lihong Hu, Yonghong Zhou and Puyou Jia

Int. J. Mol. Sci. 2023, 24(2), 1479; https://doi.org/10.3390/ijms24021479 - 12 Jan 2023

Cited by 5 | Viewed by 2178

Abstract

Lignin degradation is an effective means of achieving the high-value application of lignin, but degradation usually requires the use of high temperatures and harsh reaction-conditions. This study describes a green, mild approach for the degradation of lignin, in which chlorine dioxide (ClO₂ [...] Read more.

Lignin degradation is an effective means of achieving the high-value application of lignin, but degradation usually requires the use of high temperatures and harsh reaction-conditions. This study describes a green, mild approach for the degradation of lignin, in which chlorine dioxide (ClO₂) was used for the oxidative degradation of lignin (IL) in an acidic aqueous suspension at room temperature. The optimal process conditions were: 30 mL of ClO₂ solution (2.5 mg·L⁻¹), pH 4.5 and 3 h. The FT-IR, NMR (¹H NMR, 2D-HSQC and ³¹P NMR), XPS and GPC analyses indicated that lignin could be degraded by ClO₂ relatively well at room temperature, to form quinones and muconic acids. Additionally, DIL was reduced to substances with a high phenolic-hydroxyl (OH) content (RDIL) under the presence of NaBH₄, which further confirmed the composition of DIL and which can be applied to the development of lignin-based phenolic resins, providing a reference for the further modification as well as the utilization of DIL. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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12 pages, 3765 KiB

Open AccessArticle

A Lignin-Based Carbon Anode with Long-Cycle Stability for Li-Ion Batteries

by Shiyue Li, Wenbin Luo, Qi He, Jie Lu, Jian Du, Yehan Tao, Yi Cheng and Haisong Wang

Int. J. Mol. Sci. 2023, 24(1), 284; https://doi.org/10.3390/ijms24010284 - 23 Dec 2022

Cited by 4 | Viewed by 3193

Abstract

Due to its wide source and low cost, biomass-based hard carbon is considered a valuable anode for lithium-ion batteries (LIBs). Lignins, as the second most abundant source in nature, are being intensively studied as candidate anode materials for next generation LIBs. However, direct [...] Read more.

Due to its wide source and low cost, biomass-based hard carbon is considered a valuable anode for lithium-ion batteries (LIBs). Lignins, as the second most abundant source in nature, are being intensively studied as candidate anode materials for next generation LIBs. However, direct carbonization of pure lignin usually leads to low specific surface area and porosity. In this paper, we design a porous carbon material from natural lignin assisted by sacrificing a metal–organic framework (MOF) as the template. The MOF nanoparticles can disperse the lignin particles uniformly and form abundant mesopores in the composites to offer fast transfer channels for Li⁺. The as-prepared carbon anode shows a high specific capacity of 420 mAh g⁻¹ with the capacity retention of 99% after 300 cycles at 0.2 A g⁻¹. Additionally, it keeps the capacity retention of 85% after long cycle of 1000 cycles, indicating the good application value of the designed anode in LIBs. The work provides a renewable and low-cost candidate anode and a feasible design strategy of the anode materials for LIBs. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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13 pages, 3899 KiB

Open AccessArticle

Synthesis of Silver Nanoparticles and Detection of Glucose via Chemical Reduction with Nanocellulose as Carrier and Stabilizer

by Zhiguo Zhang, Guihua Yang, Ming He, Letian Qi, Xincai Li and Jiachuan Chen

Int. J. Mol. Sci. 2022, 23(23), 15345; https://doi.org/10.3390/ijms232315345 - 5 Dec 2022

Cited by 8 | Viewed by 2414

Abstract

The application of silver nanoparticles (AgNPs) in antibacterial materials, glucose detection, etc., is of broad interest for researchers around the world. Nanocellulose with many excellent properties can be used as a carrier and stabilizer to assist in the synthesis of AgNPs. In this [...] Read more.

The application of silver nanoparticles (AgNPs) in antibacterial materials, glucose detection, etc., is of broad interest for researchers around the world. Nanocellulose with many excellent properties can be used as a carrier and stabilizer to assist in the synthesis of AgNPs. In this study, cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were used to assist in the synthesis of AgNPs under the reduction of glucose and detection of glucose concentration under different conditions. Transmission electron microscopy (TEM) analysis showed that the AgNPs in the nanocellulose-AgNPs (NC-AgNPs) system were roughly spherical and randomly distributed on the nanocellulose. In the whole reaction system, when the concentration of nanocellulose is 0.11 mg/mL, the concentration of silver ammonia solution is 0.6 mM, and the mixing time is 2.5 h, according to the UV-Vis analysis, the absorbance of CNF-AgNPs at 425 nm exhibited a good linear relationship (R² = 0.9945) with the glucose concentration range (5–50 μM), while the absorbance of CNC-AgNPs at 420 nm showed a good linear relationship (R² = 0.9956) with the glucose concentration range (5–35 μM). The synthesis of NC-AgNPs can be further developed into a sensor with higher sensitivity and higher stability for detecting glucose concentration and a material with antibacterial effects. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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14 pages, 5281 KiB

Open AccessArticle

Phosphorylation of Kapok Fiber with Phytic Acid for Enhanced Flame Retardancy

by Xin-Lin Jiang and Ren-Cheng Tang

Int. J. Mol. Sci. 2022, 23(23), 14950; https://doi.org/10.3390/ijms232314950 - 29 Nov 2022

Cited by 7 | Viewed by 2769

Abstract

Kapok fiber (KF), with the characteristics of a natural hollow structure, light weight, and low density, can be used as acoustic and thermal insulation, buoyancy, adsorption, filling, and composite material. The flame-retardant treatment can expand the functionality and application of KF. In this [...] Read more.

Kapok fiber (KF), with the characteristics of a natural hollow structure, light weight, and low density, can be used as acoustic and thermal insulation, buoyancy, adsorption, filling, and composite material. The flame-retardant treatment can expand the functionality and application of KF. In this work, the phosphorylation of KF using phytic acid (PA) in the presence of urea at a high temperature was used to enhance its flame retardancy. The phosphorylation reaction conditions were discussed, and the surface topography, thermal degradation, heat release, and combustion properties of phosphorylated KF were studied. The Fourier transform infrared spectroscopy and ³¹P solid-state nuclear magnetic resonance spectroscopy analyses confirmed the grafting of PA on cellulose by the formation of phosphate ester bonds. Due to the covalent binding of PA, phosphorylated KF exhibited good washing durability. The surface topography, Raman spectroscopy, thermogravimetric (TG), and microcalorimetry analyses revealed the excellent charring ability of phosphorylated KF. In the TG test in nitrogen, the char residue increased to 42.6% of phosphorylated KF from 8.3% of raw KF at 700 °C. In the vertical combustion, raw KF sheet was almost completely burned out within 30 s, while phosphorylated KF was very difficult to catch fire. In the microcalorimetry analysis, the heat release capacity and total heat release of phosphorylated KF decreased to 67 J/g∙K and 3.9 kJ/g, respectively from 237 J/g∙K and 18.1 kJ/g of raw KF. This work suggests that phosphorylated KF is an excellent flame-retardant material. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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12 pages, 1389 KiB

Open AccessArticle

Transformation of Corn Stover into Furan Aldehydes by One-Pot Reaction with Acidic Lithium Bromide Solution

by Meixiang Gao, Qi Xin, Wan Sun, Jiaqi Xiao and Xianqin Lu

Int. J. Mol. Sci. 2022, 23(23), 14901; https://doi.org/10.3390/ijms232314901 - 28 Nov 2022

Cited by 2 | Viewed by 1864

Abstract

Currently, the production of furan aldehydes from raw biomass suffers from low furfural yield and high energy consumption. In this study, a recyclable and practical method was explored for the preparation of furfural from corn stover by the one-pot reaction by acidic lithium [...] Read more.

Currently, the production of furan aldehydes from raw biomass suffers from low furfural yield and high energy consumption. In this study, a recyclable and practical method was explored for the preparation of furfural from corn stover by the one-pot reaction by acidic lithium bromide solution (ALBS) without pretreatment and enzymolysis. In the ALBS reaction, the furan aldehydes were generated by the degradation of lignocellulose; however, the products were unstable and were further dehydrated to form humins. So, dehydration reaction was inhibited in this study, and the high yield of furan aldehydes was obtained, in which 2.94 g/L of furfural and 2.78 g/L of 5-hydroxymethyl furfural (5-HMF) were generated with high solid loading (10 wt%), the presence of commercial catalyst ZSM-5 and co-solvent tetrahydrofuran (THF) at 140 °C for 200 min. Via this method, almost 100% of hemicellulose was transformed to furfural, and 40.71% of cellulose was transformed to 5-HMF, which was based on the theoretical yield of HMF (8.35 g) from glucose (29.30 g) produced from cellulose. After the reaction, the catalyst ZSM-5 was the main component in the solid residue and kept a suitable performance. THF azeotrope was easily separated from the slurry by evaporation. During the removal of THF, lignin was precipitated from the liquid phase and showed lower molecular weight and abundant active groups, which was a potential feedstock for producing valuable aromatics and polymers. Thus, in a one-pot reaction, the ideal yield of furan aldehydes from raw biomass was obtained on a lab scale, and the catalyst, THF, and LiBr were easily recycled, which provided an option to realize the economical production of sustainable furan aldehydes from raw biomass. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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15 pages, 3131 KiB

Open AccessArticle

Effects of the Preferential Oxidation of Phenolic Lignin Using Chlorine Dioxide on Pulp Bleaching Efficiency

by Yi Liu, Baojuan Deng, Jiarui Liang, Jiao Li, Baojie Liu, Fei Wang, Chengrong Qin and Shuangquan Yao

Int. J. Mol. Sci. 2022, 23(21), 13310; https://doi.org/10.3390/ijms232113310 - 1 Nov 2022

Cited by 5 | Viewed by 1906

Abstract

Chlorine dioxide is widely used for pulp bleaching because of its high delignification selectivity. However, efficient and clean chlorine dioxide bleaching is limited by the complexity of the lignin structure. Herein, the oxidation reactions of phenolic (vanillyl alcohol) and non-phenolic (veratryl alcohol) lignin [...] Read more.

Chlorine dioxide is widely used for pulp bleaching because of its high delignification selectivity. However, efficient and clean chlorine dioxide bleaching is limited by the complexity of the lignin structure. Herein, the oxidation reactions of phenolic (vanillyl alcohol) and non-phenolic (veratryl alcohol) lignin model species were modulated using chlorine dioxide. The effects of chlorine dioxide concentration, reaction temperature, and reaction time on the consumption rate of the model species were also investigated. The optimal consumption rate for the phenolic species was obtained at a chlorine dioxide concentration of 30 mmol·L⁻¹, a reaction temperature of 40 °C, and a reaction time of 10 min, resulting in the consumption of 96.3% of vanillyl alcohol. Its consumption remained essentially unchanged compared with that of traditional chlorine dioxide oxidation. However, the consumption rate of veratryl alcohol was significantly reduced from 78.0% to 17.3%. Additionally, the production of chlorobenzene via the chlorine dioxide oxidation of veratryl alcohol was inhibited. The structural changes in lignin before and after different treatments were analyzed. The overall structure of lignin remained stable during the optimization of the chlorine dioxide oxidation treatment. The signal intensities of several phenolic units were reduced. The effects of the selective oxidation of lignin by chlorine dioxide on the pulp properties were analyzed. Pulp viscosity significantly increased owing to the preferential oxidation of phenolic lignin by chlorine dioxide. The pollution load of bleached effluent was considerably reduced at similar pulp brightness levels. This study provides a new approach to chlorine dioxide bleaching. An efficient and clean bleaching process of the pulp was developed. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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15 pages, 1954 KiB

Open AccessArticle

Pretreatment Strategies to Enhance Enzymatic Hydrolysis and Cellulosic Ethanol Production for Biorefinery of Corn Stover

by Wan Sun, Xuezhi Li, Jian Zhao and Yuqi Qin

Int. J. Mol. Sci. 2022, 23(21), 13163; https://doi.org/10.3390/ijms232113163 - 29 Oct 2022

Cited by 14 | Viewed by 3165

Abstract

There is a rising interest in bioethanol production from lignocellulose such as corn stover to decrease the need for fossil fuels, but most research mainly focuses on how to improve ethanol yield and pays less attention to the biorefinery of corn stover. To [...] Read more.

There is a rising interest in bioethanol production from lignocellulose such as corn stover to decrease the need for fossil fuels, but most research mainly focuses on how to improve ethanol yield and pays less attention to the biorefinery of corn stover. To realize the utilization of different components of corn stover in this study, different pretreatment strategies were used to fractionate corn stover while enhancing enzymatic digestibility and cellulosic ethanol production. It was found that the pretreatment process combining dilute acid (DA) and alkaline sodium sulfite (ASS) could effectively fractionate the three main components of corn stover, i.e., cellulose, hemicellulose, and lignin, that xylose recovery reached 93.0%, and that removal rate of lignin was 85.0%. After the joint pretreatment of DA and ASS, the conversion of cellulose at 72 h of enzymatic hydrolysis reached 85.4%, and ethanol concentration reached 48.5 g/L through fed-batch semi-simultaneous saccharification and fermentation (S-SSF) process when the final concentration of substrate was 18% (w/v). Pretreatment with ammonium sulfite resulted in 83.8% of lignin removal, and the conversion of cellulose and ethanol concentration reached 86.6% and 50 g/L after enzymatic hydrolysis of 72 h and fed-batch S-SSF, respectively. The results provided a reference for effectively separating hemicellulose and lignin from corn stover and producing cellulosic ethanol for the biorefinery of corn stover. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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15 pages, 2464 KiB

Open AccessArticle

Supramolecular Deconstruction of Bamboo Holocellulose via Hydrothermal Treatment for Highly Efficient Enzymatic Conversion at Low Enzyme Dosage

by Xinyan Wang, Peng Wang, Yan Su, Qiyao Wang, Zhe Ling and Qiang Yong

Int. J. Mol. Sci. 2022, 23(19), 11829; https://doi.org/10.3390/ijms231911829 - 5 Oct 2022

Cited by 9 | Viewed by 1981

Abstract

Hydrothermal pretreatment (HTP) has long been considered as an efficient and green treatment process on lignocellulosic biomass for bioconversion. However, the variations of cellulose supramolecular structures during HTP as well as their effects on subsequent enzymatic conversion are less understood. In this work, [...] Read more.

Hydrothermal pretreatment (HTP) has long been considered as an efficient and green treatment process on lignocellulosic biomass for bioconversion. However, the variations of cellulose supramolecular structures during HTP as well as their effects on subsequent enzymatic conversion are less understood. In this work, bamboo holocellulose with well-connected cellulose and hemicelluloses polysaccharides were hydrothermally treated under various temperatures. Chemical, morphological, and crystal structural determinations were performed systematically by a series of advanced characterizations. Xylan was degraded to xylooligosaccharides in the hydrolyzates accompanied by the reduced degree of polymerization for cellulose. Cellulose crystallites were found to swell anisotropically, despite the limited decrystallization by HTP. Hydrogen bond linkages between cellulose molecular chains were weakened due to above chemical and crystal variations, which therefore swelled, loosened, and separated the condensed cellulose microfibrils. Samples after HTP present notably increased surface area, favoring the adsorption and subsequent hydrolysis by cellulase enzymes. A satisfying enzymatic conversion yield (>85%) at rather low cellulase enzyme dosage (10 FPU/g glucan) was obtained, which would indicate new understandings on the green and efficient bioconversion process on lignocellulosic biomass. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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13 pages, 2923 KiB

Open AccessArticle

Preparation and Characterization of Degradable Cellulose−Based Paper with Superhydrophobic, Antibacterial, and Barrier Properties for Food Packaging

by Xiaofan Jiang, Qiang Li, Xinting Li, Yao Meng, Zhe Ling, Zhe Ji and Fushan Chen

Int. J. Mol. Sci. 2022, 23(19), 11158; https://doi.org/10.3390/ijms231911158 - 22 Sep 2022

Cited by 29 | Viewed by 3835

Abstract

A great paradigm for foremost food packaging is to use renewable and biodegradable lignocellulose−based materials instead of plastic. Novel packages were successfully prepared from the cellulose paper by coating a mixture of polylactic acid (PLA) with cinnamaldehyde (CIN) as a barrier screen and [...] Read more.

A great paradigm for foremost food packaging is to use renewable and biodegradable lignocellulose−based materials instead of plastic. Novel packages were successfully prepared from the cellulose paper by coating a mixture of polylactic acid (PLA) with cinnamaldehyde (CIN) as a barrier screen and nano silica−modified stearic acid (SA/SiO₂) as a superhydrophobic layer. As comprehensively investigated by various tests, results showed that the as−prepared packages possessed excellent thermal stability attributed to inorganic SiO₂ incorporation. The excellent film−forming characteristics of PLA improved the tensile strength of the manufactured papers (104.3 MPa) as compared to the original cellulose papers (70.50 MPa), enhanced by 47.94%. Benefiting from the rough nanostructure which was surface−modified by low surface energy SA, the contact angle of the composite papers attained 156.3°, owning superhydrophobic performance for various liquids. Moreover, the composite papers showed excellent gas, moisture, and oil bacteria barrier property as a result of the reinforcement by the functional coatings. The Cobb_300s and WVP of the composite papers were reduced by 100% and 88.56%, respectively, and their antibacterial efficiency was about 100%. As the novel composite papers have remarkable thermal stability, tensile strength, and barrier property, they can be exploited as a potential candidate for eco−friendly, renewable, and biodegradable cellulose paper−based composites for the substitute of petroleum−derived packages. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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11 pages, 2949 KiB

Open AccessArticle

Janus Biopolymer Sponge with Porous Structure Based on Water Hyacinth Petiole for Efficient Solar Steam Generation

by Junying Li, Sheng Chen, Cuihuan Li, Mengyao Cao, Jiahui Mu, Haq Nawaz, Zhe Ling and Feng Xu

Int. J. Mol. Sci. 2022, 23(16), 9185; https://doi.org/10.3390/ijms23169185 - 16 Aug 2022

Cited by 10 | Viewed by 2633

Abstract

Solar-driven steam generation for desalination is a facile, sustainable, and energy-saving approach to produce clean freshwater. However, the complicated fabrication process, high cost, potential environmental impact, and salt crystallization of conventional evaporators limit their large-scale application. Herein, we present a sustainable Janus evaporator [...] Read more.

Solar-driven steam generation for desalination is a facile, sustainable, and energy-saving approach to produce clean freshwater. However, the complicated fabrication process, high cost, potential environmental impact, and salt crystallization of conventional evaporators limit their large-scale application. Herein, we present a sustainable Janus evaporator based on a biopolymer sponge from the water hyacinth petiole (WHP) for high-performance solar steam generation. The freeze-dried WHP maintained its original porous structure and aligned channels well, and therefore holds the capability for rapid water transport due to strong capillary action. The WHP coated with carbon nanotubes/ethyl cellulose paste on its surface (WHP-C) gains a good photothermal property, thus achieving an efficient solar steam generation with a rate of 1.50 kg m⁻² h⁻¹ under 1 sun irradiation. Moreover, the WHP-C after hydrophobic modification by fluorocarbon (WHP-CH) is endowed with high water repellency and exhibits good salt resistance during long-term solar desalination. Additionally, we demonstrate that a stable wet surface that enables efficient water supply and vapor escape is also significant to the successive desalination of a solar evaporator. Our work provides new insights into the high-value utilization of biomass waste, i.e., water hyacinth, and the development of sustainable interfacial solar evaporators for the environmentally friendly production of freshwater. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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12 pages, 3008 KiB

Open AccessArticle

Kinetics of Lignin Separation during the Atmospheric Fractionation of Bagasse with p-Toluenesulfonic Acid

by Baojuan Deng, Yadan Luo, Meijiao Peng, Tao Li, Jianwei Su, Yang Wang, Xuelian Xia, Chengqi Feng and Shuangquan Yao

Int. J. Mol. Sci. 2022, 23(15), 8743; https://doi.org/10.3390/ijms23158743 - 6 Aug 2022

Cited by 5 | Viewed by 1895

Abstract

As a green and efficient component separation technology, organic acid pretreatment has been widely studied in biomass refining. In particular, the efficient separation of lignin by p-toluenesulfonic acid (p-TsOH) pretreatment has been achieved. In this study, the mechanism of the [...] Read more.

As a green and efficient component separation technology, organic acid pretreatment has been widely studied in biomass refining. In particular, the efficient separation of lignin by p-toluenesulfonic acid (p-TsOH) pretreatment has been achieved. In this study, the mechanism of the atmospheric separation of bagasse lignin with p-TsOH was investigated. The separation kinetics of lignin was analyzed. A non-simple linear relationship was found between the separation yield of lignin and the concentration of p-TsOH, the temperature and the stirring speed. The shrinking nucleus model for the separation of lignin was established based on the introduction of mass transfer and diffusion factors. A general model of the total delignification rate was obtained. The results showed that the process of lignin separation occurred into two phases, i.e., a fast stage and a slow stage. The results provide a theoretical basis for the efficient separation of lignin by p-TsOH pretreatment. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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11 pages, 1585 KiB

Open AccessArticle

High-Efficiency and High-Quality Extraction of Hemicellulose of Bamboo by Freeze-Thaw Assisted Two-Step Alkali Treatment

by Xin Wang, Jiahao He, Shuyu Pang, Shuangquan Yao, Chunxia Zhu, Jinwei Zhao, Yang Liu, Chen Liang and Chengrong Qin

Int. J. Mol. Sci. 2022, 23(15), 8612; https://doi.org/10.3390/ijms23158612 - 3 Aug 2022

Cited by 11 | Viewed by 2569

Abstract

Hemicellulose is a major component of the complex biomass recalcitrance structure of fiber cell walls. Even though biomass recalcitrance protects plants, it affects the effective utilization of lignocellulosic biomass resources. Therefore, the separation and extraction of hemicellulose is very important. In this study, [...] Read more.

Hemicellulose is a major component of the complex biomass recalcitrance structure of fiber cell walls. Even though biomass recalcitrance protects plants, it affects the effective utilization of lignocellulosic biomass resources. Therefore, the separation and extraction of hemicellulose is very important. In this study, an improved two-step alkali pretreatment method was proposed to separate hemicellulose efficiently. Firstly, 16.61% hemicellulose was extracted from bamboo by the weak alkali treatment. Then, the physical freezing and the alkali treatment were carried out by freezing at −20 °C for 12.0 h and thawing at room temperature, heating to 80 °C, and treating with 5.0% sodium hydroxide for 90 min; the extraction yield of hemicellulose reached 73.93%. The total extraction yield of the two steps was 90.54%, and the molecular weight and purity reached 44,865 g·mol^–1 and 89.60%, respectively. It provides a new method for breaking the biomass recalcitrance of wood fiber resources and effectively extracting hemicellulose. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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16 pages, 24024 KiB

Open AccessArticle

Efficient Separation and Recovery of Petroleum Hydrocarbon from Oily Sludge by a Combination of Adsorption and Demulsification

by Mingzhu Yao, Yun Ma, Lu Liu, Chengrong Qin, Haibo Huang, Zhiwei Zhang, Chen Liang and Shuangquan Yao

Int. J. Mol. Sci. 2022, 23(14), 7504; https://doi.org/10.3390/ijms23147504 - 6 Jul 2022

Cited by 5 | Viewed by 2597

Abstract

The treatment of oily sludge (OS) can not only effectively solve environmental pollution but also contribute to the efficient use of energy. In this study, the separation effect of OS was analyzed through sodium lignosulfonate (SL)-assisted sodium persulfate (S/D) treatment. The effects of [...] Read more.

The treatment of oily sludge (OS) can not only effectively solve environmental pollution but also contribute to the efficient use of energy. In this study, the separation effect of OS was analyzed through sodium lignosulfonate (SL)-assisted sodium persulfate (S/D) treatment. The effects of SL concentration, pH, temperature, solid–liquid ratio, revolving speed, and time on SL adsorption solubilization were analyzed. The effects of sodium persulfate dosage, demulsification temperature, and demulsification time on sodium persulfate oxidative demulsification were analyzed. The oil removal efficiency was as high as 91.28%. The results showed that the sediment was uniformly and finely distributed in the S/D-treated OS. The contact angle of the sediment surface was 40°, and the initial apparent viscosity of the OS was 56 Pa·s. First, the saturated hydrocarbons and aromatic hydrocarbons on the sediment surface were adsorbed by the monolayer adsorption on SL. Stubborn, cohesive oil agglomerates were dissociated. Sulfate radical anion (SO₄⁻·) with a high oxidation potential, was formed from sodium persulfate. The oxidation reaction occurred between SO₄⁻· and polycyclic aromatic hydrocarbons. A good three-phase separation effect was attained. The oil recovery reached 89.65%. This provides theoretical support for the efficient clean separation of oily sludge. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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13 pages, 2608 KiB

Open AccessArticle

Porous Carbon Spheres Derived from Hemicelluloses for Supercapacitor Application

by Yuanyuan Wang, Chengshuai Lu, Xuefei Cao, Qiang Wang, Guihua Yang and Jiachuan Chen

Int. J. Mol. Sci. 2022, 23(13), 7101; https://doi.org/10.3390/ijms23137101 - 26 Jun 2022

Cited by 35 | Viewed by 3301

Abstract

With the increasing demand for dissolving pulp, large quantities of hemicelluloses were generated and abandoned. These hemicelluloses are very promising biomass resources for preparing carbon spheres. However, the pore structures of the carbon spheres obtained from biomass are usually poor, which extensively limits [...] Read more.

With the increasing demand for dissolving pulp, large quantities of hemicelluloses were generated and abandoned. These hemicelluloses are very promising biomass resources for preparing carbon spheres. However, the pore structures of the carbon spheres obtained from biomass are usually poor, which extensively limits their utilization. Herein, the carbon microspheres derived from hemicelluloses were prepared using hydrothermal carbonization and further activated with different activators (KOH, K₂CO₃, Na₂CO₃, and ZnCl₂) to improve their electrochemical performance as supercapacitors. After activation, the specific surface areas of these carbon spheres were improved significantly, which were in the order of ZnCl₂ > K₂CO₃ > KOH > Na₂CO₃. The carbon spheres with high surface area of 2025 m²/g and remarkable pore volume of 1.07 cm³/g were achieved, as the carbon spheres were activated by ZnCl₂. The supercapacitor electrode fabricated from the ZnCl₂-activated carbon spheres demonstrated high specific capacitance of 218 F/g at 0.2 A/g in 6 M KOH in a three-electrode system. A symmetric supercapacitor was assembled in 2 M Li₂SO₄ electrolyte, and the carbon spheres activated by ZnCl₂ showed excellent electrochemical performance with high specific capacitance (137 F/g at 0.5 A/g), energy densities (15.4 Wh/kg), and good cyclic stability (95% capacitance retention over 2000 cycles). Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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15 pages, 5499 KiB

Open AccessArticle

Comparison of Properties of Poly(Lactic Acid) Composites Prepared from Different Components of Corn Straw Fiber

by Zhongyu Qi, Baiwang Wang, Ce Sun, Minghui Yang, Xiaojian Chen, Dingyuan Zheng, Wenrui Yao, Yang Chen, Ruixiang Cheng and Yanhua Zhang

Int. J. Mol. Sci. 2022, 23(12), 6746; https://doi.org/10.3390/ijms23126746 - 16 Jun 2022

Cited by 24 | Viewed by 2871

Abstract

In recent years, under the pressure of resource shortage and white pollution, the development and utilization of biodegradable wood-plastic composites (WPC) has become one of the hot spots for scholars’ research. Here, corn straw fiber (CSF) was chosen to reinforce a poly(lactic acid) [...] Read more.

In recent years, under the pressure of resource shortage and white pollution, the development and utilization of biodegradable wood-plastic composites (WPC) has become one of the hot spots for scholars’ research. Here, corn straw fiber (CSF) was chosen to reinforce a poly(lactic acid) (PLA) matrix with a mass ratio of 3:7, and the CSF/PLA composites were obtained by melt mixing. The results showed that the mechanical properties of the corn straw fiber core (CSFC) and corn straw fiber skin (CSFS) loaded PLA composites were stronger than those of the CSFS/PLA composites when the particle size of CSF was low. The tensile strength and bending strength of CSFS/CSFC/PLA are 54.08 MPa and 87.24 MPa, respectively, and the elongation at break is 4.60%. After soaking for 8 hours, the water absorption of CSF/PLA composite reached saturation. When the particle size of CSF is above 80 mesh, the saturated water absorption of the material is kept below 7%, and CSF/PLA composite has good hydrophobicity, which is mainly related to the interfacial compatibility between PLA and CSF. By observing the microstructure of the cross section of the CSF/PLA composite, the research found that the smaller the particle size of CSF, the smoother the cross section of the composite and the more unified the dispersion of CSF in PLA. Therefore, exploring the composites formed by different components of CSF and PLA can not only expand the application range of PLA, but also enhance the application value of CSF in the field of composites. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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16 pages, 2790 KiB

Open AccessArticle

Customized Utilization Strategies of Industrial Lignin to Produce Adsorbents and Flocculants Based on Fractionation and Adequate Structural Interpretation

by Lei Wang, Dewei Yang, Xiaohan Li, Xinyi Zhu, Jungang Jiang, Yifan Zhang, Xue Chen and Hongbo Yu

Int. J. Mol. Sci. 2022, 23(12), 6617; https://doi.org/10.3390/ijms23126617 - 14 Jun 2022

Viewed by 1989

Abstract

Lignin, a by-product of pulping and biorefinery, has great potential to replace petrochemical resources for wastewater purification. However, the defects of lignin, such as severe heterogeneity, inferior reactivity and poor solubility, characterize the production process of lignin-based products by high energy consumption and [...] Read more.

Lignin, a by-product of pulping and biorefinery, has great potential to replace petrochemical resources for wastewater purification. However, the defects of lignin, such as severe heterogeneity, inferior reactivity and poor solubility, characterize the production process of lignin-based products by high energy consumption and serious pollution. In this study, several lignin fractions with relatively homogeneous structure were first obtained by organic solvent fractionation, and their structures were fully deciphered by various characterization techniques. Subsequently, each lignin component was custom-valued for wastewater purification based on their structural characteristics. Benefiting from the high reactivity and reaction accessibility, the lignin fraction (lignin-1) refined by dissolving in ethanol and n-butanol could been used as a raw material to produce cationic lignin-based flocculant (LBF) in a copolymerization system using green, cheap and recyclable ethanol as solvent. The lignin fraction (lignin-2) extracted by methanol and dioxane showed low reactivity and high carbon content, which was used to produce lignin-based activated carbon (LAC) with phosphoric acid as activator. Moreover, the influences of synthetic factors on the purification capacity were discussed, and the LBF and LAC produced under the optimal conditions showed distinguished purification effect on kaolin suspension and heavy metal wastewater, respectively. Furthermore, the corresponding purification mechanism and external factors were also elaborated. It is believed that this cleaner production strategy is helpful for the valorization of lignin in wastewater resources. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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16 pages, 2403 KiB

Open AccessArticle

Structural Properties and Hydrolysability of Paulownia elongate: The Effects of Pretreatment Methods Based on Acetic Acid and Its Combination with Sodium Sulfite or Sodium Sulfite

by Hanxing Wang, Ni Chen, Feifan Xie, Erkki Verkasalo and Jie Chu

Int. J. Mol. Sci. 2022, 23(10), 5775; https://doi.org/10.3390/ijms23105775 - 21 May 2022

Cited by 6 | Viewed by 1918

Abstract

The effects of CH₃COOH and Na₂SO₃ pretreatment on the structural properties and hydrolyzability of fast-growing Paulownia elongate were investigated. Acetic acid increased cellulose’s crystallinity and hydrolyzability when combined with alkaline sodium sulfite and sodium hydroxide. The cellulose content [...] Read more.

The effects of CH₃COOH and Na₂SO₃ pretreatment on the structural properties and hydrolyzability of fast-growing Paulownia elongate were investigated. Acetic acid increased cellulose’s crystallinity and hydrolyzability when combined with alkaline sodium sulfite and sodium hydroxide. The cellulose content increased by 21%, the lignin content decreased by 6%, and the product showed better enzymatic digestibility. With a cellulase dose of 30 FPU/g DM, after 72 h hydrolysis, the hydrolysis yields of glucose and xylose were 78% and 83%, respectively, which were 51% and 69% higher than those of untreated materials. When the enzyme dosage was 20 FPU/g DM, after 72 h hydrolysis, the hydrolysis yields of glucose and xylose were 74% and 79%, respectively. The high hydrolyzability, low enzyme loading, and high hydrolysis yield demonstrate the potential of the proposed system for producing platform sugars from fast-growing Paulownia elongate. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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12 pages, 3582 KiB

Open AccessArticle

Biomimetic Robust Starch Composite Films with Super-Hydrophobicity and Vivid Structural Colors

by Yateng Wang, Jianru Fan, Hao Zhao, Xiaoming Song, Zhe Ji, Congxia Xie, Fushan Chen and Yao Meng

Int. J. Mol. Sci. 2022, 23(10), 5607; https://doi.org/10.3390/ijms23105607 - 17 May 2022

Cited by 4 | Viewed by 2652

Abstract

The starch composite films (SCFs) will be one of the best alternative packaging materials to petroleum based plastic films, which mitigates white pollution and energy consumption. However, weak mechanical stability, water resistance, and dyeability has hindered the application of SCFs. Herein, a bioinspired [...] Read more.

The starch composite films (SCFs) will be one of the best alternative packaging materials to petroleum based plastic films, which mitigates white pollution and energy consumption. However, weak mechanical stability, water resistance, and dyeability has hindered the application of SCFs. Herein, a bioinspired robust SCFs with super-hydrophobicity and excellent structural colors were prepared by fiber-reinforcement and assembling SiO₂/Polydimethylsiloxane (PDMS) amorphous arrays on the surface of SCFs. The properties of the designed SCFs were investigated by various methods including scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), a tensile test, contact angle (CA) test, and an optical test. The results showed that the obtained SCFs possessed a higher tensile strength (55.17 MPa) attributed to the formed abundant hydrogen bonds between the molecular chains of the starch, cellulose fiber, and polyvinyl alcohol. Benefiting from the nanostructure with rough surface which were modified by materials with low surface free energy, the contact angle and sliding angle of the film reached up to 154° and 2°, respectively. The colors which were produced by the constructive interference of the coherent scattered light could cover all of the visible regions by tuning the diameters of the SiO₂ nanoparticles. The strategy in the present study not only reinforces the mechanical strength and water resistance of SCFs but also provides an environmentally friendly way to color the them, which shows unprecedented application potential in packaging materials of the starch composite films. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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Review

Jump to: Research

19 pages, 4095 KiB

Open AccessReview

Research Progress on the Preparation and High-Value Utilization of Lignin Nanoparticles

by Kefeng Liu, Yuntang Zhuang, Jiachuan Chen, Guihua Yang and Lin Dai

Int. J. Mol. Sci. 2022, 23(13), 7254; https://doi.org/10.3390/ijms23137254 - 29 Jun 2022

Cited by 16 | Viewed by 5019

Abstract

Lignin nanoparticles, the innovative achievements in the development and utilization of lignin, combine the structural characteristics of nanomaterials and lignin molecules and have a wide range of applications. In this review, we summarize the methods for preparing lignin nanoparticles by solvent exchange method, [...] Read more.

Lignin nanoparticles, the innovative achievements in the development and utilization of lignin, combine the structural characteristics of nanomaterials and lignin molecules and have a wide range of applications. In this review, we summarize the methods for preparing lignin nanoparticles by solvent exchange method, mechanical method, biological enzymatic method, interface polymerization/crosslinking method, and spray freezing method, and emphatically introduce the application prospects of lignin nanoparticles in ultraviolet protection, antibacterial, nano-filler, drug delivery, and adsorption, aiming to provide a certain reference direction for additional high-value applications of lignin nanoparticles. Full article

(This article belongs to the Special Issue Bio-Polymer Materials and Bio-Refinery)

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