Search

In recent years, researchers have put much attention on the improvements and upgrades of novel wet strength agent in the papermaking fields, especially in the usage of household paper. Herein, PEI M -KH560 by polyethyleneimine (PEI) and γ-glycidyl ether propyl trimethoxysilane (KH560) was synthesized with five molecular weights (Mw) of PEI at 600, 1800, 10,000, 70,000 and 750,000. Results showed that the molecular weight greatly influenced the physicochemical properties of PEI-KH560, such as the size and thermal stability. The intrinsic cationic charge of PEI-KH560 provided the bonding sites with the paper fibers, forming strengthened fiber-fiber joints. It was shown that the dry, wet strength and hydrophobicity of cellulosic paper sheets were obviously improved. When the m (PEI):m(KH560) is 1:2, the strength of papers after sizing by Mw of PEI at 600 and 1800 is the most obvious, with the dry strength increased by 227.9 % and 187.5 %, and the wet strength increased by 183.8 % and 207.8 %, respectively. The maximum hydrophobicity was found at the PEI 1800 -KH560 with the contact angle value of 130.6°. The resultant environmental-friendly agent (PEI-KH560) obtained in this work provides valuable significance for the preparation of household and food packaging paper., Competing Interests: Declaration of competing interest The authors declare that they have no known competing interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, the base film (CSL) was prepared by blending tunicate cellulose nanocrystals (TCNCs) extracted from tunicate shells, with sodium alginate (SA) and alkali lignin (AL). Then, the mulching film (CSL-WK) was prepared using water-borne polyurethane (WPU) as binder to install low-energy Kaolin on the surface of CSL film. The influences of composition with different concentrations on mechanical properties were studied. The tensile strength and elongation at break of CSL-WK film could reach 86.58 MPa and 50.49 %, respectively. The mulching films were characterized by degradability test, SEM, FTIR, and TGA. TCNCs had good compatibility with SA and AL, and a rough structure was formed on the surface of the film to improve the hydrophobicity. The barrier properties, including ultraviolet resistance, water contact angle, water vapor permeability, water retention, and flame retardancy, were tested. The results showed that CSL-WK films could block 97 % of ultraviolet light, reduce about 25 % of soil water loss, and self-extinguish within 7 s of open flame ignition. Note that the secondary spraying method significantly improved the barrier property of films. This study lays a foundation for the preparation of ecologically friendly, biodegradable, and high barrier mulching film, and expands the application of marine resources., 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. Published by Elsevier B.V.)

A practical method for the preparation of lignin derivatives-light-colored bio-based particles (LC-BP) via the modification of hexamethylene diisocyanate (HDI) is presented in this work. In the mixed EtOH/H 2 O system, the change of solvent polarity induced the self-assembly of the lignosulfonate (LS) with the hydrophobic chromophores encapsulated inside the particles. The color of LS was reduced by the polymerization between the isocyanate groups (-N=C=O) of HDI and hydroxy groups of LS. Compared with the typical lignin-based adsorbent preparation process in the past, this is a simple, direct, and efficient preparation method and the synthetic LC-BP has good chemical stability and resistance to heat, acid and alkali. This effectively solves the problem that LS has high water solubility and is difficult to use directly for wastewater treatment. To investigate the properties, the synthetic LC-BP was characterized by SEM, specific surface area, L*a*b* (CIELAB) color space, FT-IR, XPS, and TGA. The results showed that the LC-BP exhibited obvious advantages in color reduction with a low CIE-L* value. The LC-BP exhibits a scale-like intercalation structure, which makes it a promising candidate for adsorbing tetracycline (TC) from wastewater. The conditions of pH, adsorbent dosages, adsorption time, and initial TC concentration were investigated, and the adsorption performance of LC-BP for TC was significantly better than that of conventional polyurethane particles (PP). The adsorption fitted the Langmuir model and there were hydrogen bonding, π-π conjugated binding, and electrostatic attraction during the absorption process. The adsorption capacity was up to 53.1 mg/g, and the removal rate was 67 %. The utilization of LC-BP, a low-cost, effective, and renewable resource derived from natural biomass, holds immense practical and economic potential in wastewater treatment., 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 © 2023 Elsevier B.V. All rights reserved.)

Cellulose nanocrystal (CNC) hybrid materials with numerous optical states have great potential as anti-counterfeiting labels and information encryption materials. However, it is challenging to construct multicolor emitting materials with tunable behaviors, which can dramatically enhance anti-counterfeiting abilities. Here, free-standing composite films with vivid multi-structural colors and dual-emitting fluorescence are successfully fabricated through a host-guest coassembly strategy. The lanthanide complex and an aggregation-induced emission molecule (tetraphenylethylene derivative, TPEC) are selected as luminescent guests, which are integrated into the chiral nematic structure of CNCs. The obtained photonic films display broadband reflection across the visible spectrum, which may be attributed to the chiral nematic domains with variations in the helical pitches and helical axis orientations. Under 254 nm excitation, the film exhibits bright red emission, while blue-green emission switching occurs under 365 nm excitation. The broad reflection band of the film covers both the green and red fluorescent emission centers, and right circularly polarized luminescence emission with different dissymmetry factors is produced due to the selective reflection of the left chiral nematic structure. A large glum value up to -0.21 at 600 nm was realized. Additionally, CNC-based materials with tailored shapes are further used in anti-counterfeit tags and decorative applications., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2023. Published by Elsevier Ltd.)

Biomass pretreatment is an essential strategy to overcome biomass recalcitrance and promote lignocellulosic bioconversion. Here, a reusable organic solvent system (formic acid-methanesulfonic acid) was explored to pretreat poplar under a mild temperature (below 100 °C). The results showed that the co-solvent system could extract basically complete hemicelluloses and part of lignin with original cellulose retained in the pretreated substrates. Meanwhile, sulfonic acid groups were introduced into lignin structure remained in the substrates. The glucose conversion yield of the substrates with a higher concentration of sulfonic acid groups (13.2 mmol/kg) reached 45.9 % by reducing the hydrophobic interaction between lignin and cellulase, showing 89.3 % improvement compared with that of the substrates treated with single formic acid. This progressive study aimed to develop a new strategy to realize sulfonation and promote enzymatic hydrolysis of substrates by using mild organic solvent pretreatment., 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 Elsevier Ltd. All rights reserved.)

In this study, a heat-resistant and high-wettability lithium-ion batteries separator (PI-CPM-PI) composed of cellulose nanofibers (CNF) and aramid fibers (PMIA chopped fiber/PPTA pulp) with the reinforced concrete structure was fabricated via a traditional heterogeneous paper-making process. CNF played crucial roles in optimizing the pore structure and improving the wettability of PI-CPM-PI separator. The effects of composition on separator properties were investigated and the results indicated that the optimal compositions were 0.5 wt% CNF, 0.5 wt% PMIA chopped fiber/PPTA pulp (ratio of 5:5), 0.05 wt% diatomite and 1.5 wt% polyimide. Relevant tests demonstrated that the performance advantages of PI-CPM-PI separators were exhibited at the wettability and thermal stability compared to the commercial separator (PP). Additionally, batteries assembled with PI-CPM-PI separators showed excellent electrochemical and cycling performance (ionic conductivity of 1.041 mS.cm -1 , the first discharge capacity of 158.2 mAh.g -1 at 0.2C and capacity retention ratio of 99.76 % after 100 cycles)., Competing Interests: Declaration of competing interest None., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This work aimed to construct a polysaccharide-based mulch film with good performance for replacing plastic mulch by coating the glutaraldehyde crosslinking chitosan and humic acid/urea complexes (GCS) into cellulose/humic acid (HA/CE) film. By flow-coating with GCS to construct hierarchical networks, GCS-HA/CE film is endowed with the improved property. The influences of composition with different concentrations on mechanical properties were studied, and the optimum concentration was determined. The tensile strength and elongation of GCS-HA/CE film could reach 53.97 MPa and 12.86 % in dry state, respectively. Results suggest that glutaraldehyde crosslinking reduces moisture content, water solubility, and water vapor permeability, but increases contact angle (94.025°). Meanwhile, the thermostability and ultraviolet resistance were improved. The infrared spectroscopy and X-ray diffractometry demonstrated the successfully crosslinked by glutaraldehyde. Morphological analyses present film has excellent compatibility. In addition, GCS-HA/CE film shows good heat preservation, aging resistance, and biodegradability, indicating certain guiding significance for polysaccharide-based mulch film., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Solar desalination devices utilizing sustainable solar energy and the abundant resource of seawater has great potential as a response to global freshwater scarcity. Herein, a bilayered solar evaporator was designed and fabricated utilizing a facile paper sheet forming technology, which was composed of cellulose fibers decorated with Fe 3 O 4 nanoparticles as the top absorbent layer and the original cellulose fibers as the bottom supporting substrate. The characterization of the cellulose fibers decorated with Fe 3 O 4 nanoparticles revealed that the in situ formed Fe 3 O 4 nanoparticles were successfully loaded on the fiber surface and presented a unique rough surface, endowing the absorber layer with highly efficient light absorption and photothermal conversion. Moreover, due to its superhydrophilic property, the cellulose fiber-based bottom substrate conferred ultra-speed water transport capability, which could enable an adequate water supply to combat the water loss caused by continuous evaporation on the top layer. With the advantages mentioned above, our designed bilayered paper-based evaporator achieved an evaporation rate ~1.22 kg m -2 h -1 within 10 min under 1 sun irradiation, which was much higher than that of original cellulose cardboard. Based on the simple and scalable manufacture process, the bilayered paper-based evaporator may have great potential as a highly efficient photothermal conversion material for real-world desalination applications.

In view of the deficiencies in the preparation of cellulose gels, such as, cumbersome process, harsh conditions, high consumption of chemicals, secondary pollution caused by side reactions, this work reports a facile approach to make cellulose/multi-walled carbon nanotube (MWCNTs) hydrogels and aerogels via mixing cellulose with N,N'-methylene bisacrylamide (MBA) and MWCNTs in NaOH/urea/H 2 O aqueous solution. The gels were revealed to be formed by an addition reaction between the double bonds of MBA and the hydroxyl groups of cellulose and the intermolecular interactions between cellulose and MWCNTs. The preparation process can be realized at room temperature and atmospheric pressure without the intervention of ultrasonic dispersion, catalyst and initiator. The gelation time, puncture strength and water retention ability of the hydrogels were investigated. Results showed that, compared with pure cellulose hydrogel, cellulose/MWNCTs hydrogels have obviously shorter sol-gel transition time (124-129.2 min), higher puncture strength (29.6022-34.2854 KPa) and water retention ability (274.2619-301.7291 g/g). Cellulose/MWCNTs aerogels possessed three dimensional network with macroporous structure (about 500 μm), low density (0.00546-0.00557 g/cm 3 ), high porosity (99.6360-99.6426 %), good thermal stability (242 °C) and certain absorbency to methylene blue (233.2901-242.1122 mg/g)., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Chiral nematic papers (CNPs) with mesopores structure based on cellulose nanocrystals (CNCs) were fabricated successfully via a swelling and freeze-drying method. The order of the original chiral nematic cellulose nanocrystals film was preserved in CNPs, which was proved by scanning electron microscopy (SEM), polarized optical microscopy (POM) measurements and circular dichroism (CD) spectra. The CNPs exhibited excellent optical responsive properties to different solvents. Inspired by this feature, a colorable ink containing amounts of gel particles was prepared by pulverizing CNPs/water mixture into a suspension. Patterns written in suspension ink with various colors can be formed when soaked with different solvents. Moreover, CNPs displayed an irreversible color response to compression. Additionally, the hydrophilicity of CNPs was tuned by polyethyleneimine. Modified CNPs exhibited different colors under the identical solvent environment when compared to the original one. Aqueous PEI can be used as an ink to depict responsive photonic patterns on CNPs., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Thehighly efficient utilization of lignin is of great importance for the development of the biorefinery industry. Herein, a novel "core-shell" lignin nanoparticle (LNP) with a diameter of around 135 nm was prepared, after the lignin was isolated from the effluent of formic acid fractionation via dialysis. In an attempt to endow composite materials with vital functionalities, the LNP was added to the starch film and the starch/polyvinyl alcohol (PVA) or starch/polyethylene oxide (PEO) composite film. The results showed that the hydrophobicity performance of the synthesized films was enhanced significantly. Specifically, the dynamic water contact angle value of the starch/PVA composite film with 1% (wt) addition of LNPs could be maintained as high as 122° for 180 s; the starch/PEO composite film also achieved an excellent water contact angle above 120°. The addition of LNPs promoted the formation of some rough structures on the film surface, as shown by the scanning electron microscopy images, which could repel the water molecules efficiently and are closely related to the enhanced hydrophobicity of the starch film. What is more, the as-prepared LNP conferred strengthened thermal stability and ultraviolet blocking properties on the starch composite film. The structural combination of the polymer film with LNPs holds the promise for providing advanced functionalities to the composite material with wide applications.

During the traditional autohydrolysis, formation and deposition of "pseudo-lignin" and lignin droplets on the surface of biomass had a detrimental effect on the subsequent biomass conversion. In this study, isothermal phase separation was introduced into autohydrolysis, and the effects of isothermal phase separation on the dissolution of components and enzymatic hydrolysis of bamboo were studied. The research showed that isothermal phase separation after autohydrolysis without cooling had an effective reduction in the deposition of "pseudo-lignin" and lignin droplets on the residues surface. After isothermal phase separation, the contents of sugar (14.05 g/L) and lignin (6.16 g/L) in pre-hydrolysates increased by 20% and 19% compared with control, respectively. Moreover, the efficient removal of "pseudo-lignin" and lignin droplets from cell wall surface could further promote the biological conversion of pretreated biomass (22% higher than that of control) during the subsequent enzymatic hydrolysis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Biografting is a promising and ecofriendly approach to meet various application requirements of products. Herein, a popular green enzyme, laccase, was adopted to graft a hydrophobic phenolic compound (lauryl gallate, LG) onto chitosan (CTS). The resultant chitosan derivate (Lac/LG-CTS) was systematically analyzed by Fourier transform infrared (FTIR), grafting efficiency, scanning probe microscopy (SPM), and X-ray diffraction (XRD). This grafting technique produced a multifunctional chitosan copolymer with remarkably enhanced antioxidant property, hydrophobicity, and moisture barrier property. Furthermore, the swelling capacity and acid solubility of the copolymer film decreased significantly, although the tensile strength and elongation were slightly weakened as compared to those of native chitosan. These results suggest that the Lac/LG-CTS holds great potential as a food-packaging material, preservative agent, or edible coating material.

Integrated fractionation process based on autohydrolysis (H) and subsequent formic acid delignification (FAD) has been considered as an effective strategy to separate the main lignocellulosic components in view of the biorefinery. For the better understanding of the structural changes of the lignin during the integrated process, the fractionated aspen lignins were thoroughly characterized by Fourier transform infrared (FT IR), 13 C, two-dimensional heteronuclear single quantum coherence (2D-HSQC) and 31 P nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Compared to the milled wood lignin (MWL), the fractionated lignins had higher amounts of phenolic OH groups as due to the cleavage of β-O-4 linkages and less alcoholic OH groups mainly due to the esterification of the aliphatic OH groups by formic acid. Demethylation action of the lignin was not significant during the FAD process. More syringyl-propane (S) units were extracted during the H-FAD process than guaiacyl-propane (G) units resulting in a higher S/G ratio and more OCH 3 in the fractionated lignins. Furthermore, autohydrolysis of aspen at higher temperature led to more condensation of the fractionated lignins which exhibited higher molecular weight and more β-5 and β-β linkages. The fractionated lignins exhibited high purities due to the breakage of the lignin-carbohydrate bonds., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The removal of lignin is important to the recovery of saccharides from the pre-hydrolysis liquor (PHL) in kraft-based dissolved pulp production. A one-step process for lignin removal from PHL via treatment with horseradish peroxidase (HRP) in the presence of Ca 2+ was proposed, and its principle was studied. The results demonstrated synergy between HRP and Ca 2+ in lignin removal from PHL, whereas NH 4 + had little effect on lignin removal. HRP treatment in the presence of 60 mmol/L of Ca 2+ resulted in a lignin removal of 64.8% accompanied by a saccharide loss of 14.2%. HRP catalyzed both the polymerization and depolymerization of the lignin in the PHL. The HRP-catalyzed lignin polymerization rendered some lignin insoluble enabling it to be directly removed. The HRP-catalyzed depolymerization of lignin decreased its molecular weight with an evident increase in its carboxyl content. The insoluble complexes formed between the lignin with carboxyl and the Ca 2+ facilitated the removal of the depolymerized lignin., 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 © 2020 Elsevier B.V. All rights reserved.)

Artificial antioxidants are synthesized from fossil sources and are now widely used in the polymer, food, and cosmetics industries. The gradual depletion of fossil resources makes it practically significant and necessary to produce green antioxidants from renewable lignocellulosic resources. Herein, short-time hydrothermal (STH) treatment was developed for production of lignin-derived polyphenol antioxidants (LPAs) from poplar wood under conditions of high temperature and high pressure. LPA yields from 21.5 to 37.6 % on the basis of lignin in untreated wood were obtained by STH treatments as result of lignin depolymerization at 190-200 °C and 10 MPa in 5-8 min. Depolymerization reactions were confirmed by the much lower molecular weight of LPA (1076 g mol -1 ) than that of native lignin (4094 g mol -1 ). NMR spectroscopy revealed the structural features of lignin in the isolated LPA, namely syringyl and guaiacyl units with well-preserved interunit linkages. A Folin-Ciocalteu assay indicated that each LPA molecule contained 5.4 phenolic hydroxyl groups on average, much more than other technical lignins. The remarkable antioxidant ability of LPA was verified by the radical-scavenging index of 53.5-67.3, much higher than 0.2-11.1 of the commercial antioxidants butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). STH treatment only requires water and heat for production of high-value antioxidant, which provides a green and sustainable method for the utilization of lignocelluloses., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A type of cellulose solvent, i.e., aqueous N-methylmorpholine- N-O xide (NMMO) solutions, was used to modify cellulose nanocrystal (CNC) photonic films. CNC films can be swollen by NMMO, resulting in red-shifted reflected colors. The swelling effect is supposed to come from NMMO permeation into the crystalline regions of individual CNCs and intercalating in between CNC particles. When NMMO was removed, the reflected colors of CNC films blue shifted because of the reduced helical pitches. NMMO-treated CNC films display reversible responsive colors to humidity changes in several minutes. Increasing NMMO content allows CNC films to enlarge the responsive color range. Aqueous NMMO can be used as an ink to depict responsive photonic patterns on CNC films. This post-treatment approach to producing responsive colors and photonic patterns in CNC films may be applied to the areas of sensor, anti-counterfeiting, and decoration., (Copyright © 2019. Published by Elsevier Ltd.)

Developing actuators with multi-responsibility, large deformation, and predefined shapes is critical for the application of actuators in the field of artificial intelligence. Herein, we report the preparation of a new type of unimorph actuators containing phenol-formaldelyde resin (PFR) and graphene oxide (GO) using the chiral nematic structure of cellulose nanocrystals (CNCs) as the template. The so-obtained PFR/GO films have a unimorph structure with an asymmetric distribution of GO across the film. They exhibit synchronous responses of both photonic properties and actuation to humidifying/dehumidifying. Moreover, PFR/GO films can be forged into desired shapes by aldehyde treatment, and thereby are able to produce complex movements. In addition, the objects with predetermined shapes show good shape recovery capability upon many wetting-drying cycles, especially through the treatment with formaldehyde. A mechanism model for shape predetermination by aldehyde treatment is suggested based on experimental details. By further designing the predetermined shapes and patterns, such PFR/GO actuators may hold great promise for smart actuation devices of highly complex movements.

Whole valorization of carbohydrate and lignin from biomass was achieved by rapid flow-through fractionation (RFF) within 15 min. Wheat straw was effectively deconstructed into its principle components without degradation by using easily recyclable aqueous formic acid (72 wt %) at 130 °C. The obtained cellulose-rich solid showed a nearly complete glucan recovery and 73.8 % glucose conversion after enzymatic hydrolysis. Xylan also reached full recovery with negligible furfural formation with a sum of 80 % of oligo/mono xylose in spent liquor and 20 % of xylan remaining in the solid. Up to 75.4 % lignin was dissolved in the spent liquor and further fractionated into water-insoluble (WIL) and water-soluble lignin (WSL) by dilution with water. WIL showed a non-condensed and well-preserved structure with 84.5 % β-O-4 remaining, which is believed to be beneficial for catalytic conversion into low-molecular-weight chemicals and fuels. The concentration of employed formic acid was below the formic acid/water azeotrope, and therefore the reaction medium could be restored through simple distillation. Together with the joint valorization of lignin and carbohydrates, the presented RFF is a promising process for sustainable biorefinery., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Formic acid/water binary solvent extraction with formic acid fraction lower than 77.5% (w/w) of azeotrope was used to extract hemicellulose-derived saccharides from poplar wood at various levels of severity. The highest xylose yield of 77.8% and arabinose yield of 93.5% were obtained at 120 °C and 1 h. To reduce cellulose hydrolysis and facilitate downstream xylose crystallization, mild conditions at 90 °C and 4 h was chosen as optimum severity, which led to the highest xylose fraction of 81.7% in all saccharides extracted, with a remarkable xylose yield of 73.1%. Mass balance analysis showed that 5.84% of xylan was degraded, but only 0.25% of xylan ended up as furfural at optimum severity. The proposed extraction process has high feasibility for industrial application since the low formic acid fraction in solvent allows simple recovery and concentration of used solvent., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In this study, the pre-hydrolysis liquor (PHL) was recycled during aspen chip water pre-hydrolysis, and the effects of PHL recycling on the extraction and accumulation of the hemicellulosic saccharides especially that with high molecular weight in the PHL were studied. The results showed that the concentration of hemicellulose saccharides in PHL depended on the pre-hydrolysis temperature and PHL recycling times. Compared to the unrecycled PHL, the concentration of hemicellulosic saccharides in PHL increased significantly when recycling PHL once or twice at 170°C. Furthermore, the amount of high-molecular-weight hemicelluloses (HMHs) in PHL recycled once at 170°C increased from 2.58g/L (unrecycled) to 6.18g/L, but the corresponding average molecular weight of HMHs decreased from 9.2kDa to 7.6kDa. The concentration of hemicellulosic saccharides in PHL decreased with PHL recycling time at 180°C, accompanied by the formation of a significant amount of furfural., (Copyright © 2017. Published by Elsevier Ltd.)

A novel nanocomposite based on black wattle (BW) tannin and nanocellulose was prepared and applied in heavy metal ions adsorptive removal from aqueous solutions. Firstly, nanocrystalline cellulose was oxidized by sodium periodate to get dialdehyde nanocellulose (DANC). BW tannin was then covalently immobilized onto DANC, which was used as both the matrix and crosslinker, to obtain tannin-nanocellulose (TNCC) composite. The resulting nanocomposite was characterized using FTIR, AFM, and TG. The successful immobilization was confirmed by the chromogenic reaction between FeCl 3 and TNCC and FT-IR analysis. AFM images revealed that TNCC was ellipsoidal particles with lengths ranging from 100-400nm. Zeta potential measurement showed that TNCC was negative charged at a pH range from 1-12. Compared to the original tannin, the thermal stability of TNCC was slightly increased by the addition of nanocellulose. TNCC demonstrated the maximum adsorption efficiency at pH2 for Cr(VI) and pH 6 for Cu(II) and Pb(II), respectively. The adsorption for these three metal ions followed pseudo second-order kinetics, indicating the chemisorption nature. The adsorption isotherms all fitted well with the Sips model, and the calculated maximum adsorption capacities were 51.846mgg -1 , 53.371mgg -1 and 104.592mgg -1 for Cu(II), Pb(II) and Cr (VI), respectively., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Prehydrolysis of lignocellulose produces abundant hemicellulose-derived saccharides (HDS). To obtain pure HDS for application in food or pharmaceutical industries, the prehydrolysis liquor (PHL) must be refined to remove non-saccharide compounds (NSC) derived from lignin depolymerization and carbohydrate degradation. In this work, activated carbon (AC) adsorption was employed to purify HDS from NSC with emphasis on adsorption selectivity. The adsorption isotherms showed the priority of NSC to be absorbed over HDS at low AC level. However, increase of AC over 90% of NSC removal made adsorption non-selective due to competitive adsorption between NSC and HDS. Size exclusion chromatography showed that the adsorption of oligomeric HDS was dominant while monomeric HDS was inappreciable. The limited selectivity suggested that AC adsorption is infeasibility for HDS purification, but applicable as a pretreatment method., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A combined process of lime treatment and mixed bed ion exchange was proposed to separate hemicellulose-derived saccharides (HDS) from prehydrolysis liquor (PHL) of lignocellulose as value added products. The optimization of lime treatment achieved up to 44.2% removal of non-saccharide organic compounds (NSOC), mainly colloidal substances, with negligible HDS degradation at 0.5% lime level and subsequent neutralization by phosphoric acid. The residual NSOC and calcium ions in lime-treated PHL were eliminated by mixed bed ion exchange. The breakthrough curves of HDS and NSOC showed selective retention toward NSOC, leading to 75% HDS recovery with 95% purity at 17 bed volumes of exchange capacity. In addition, macroporous resin showed higher exchange capacity than gel resin as indicated by the triple processing volume. The remarkable selectivity of the combined process suggested the feasibility for HDS separation from PHL., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The presence of transition metals during the hydrogen peroxide bleaching of pulp results in the decomposition of hydrogen peroxide, which decreases the bleaching efficiency. In this study, chitosans were used as peroxide stabilizer in the alkaline hydrogen peroxide bleaching of aspen chemithermomechanical pulp (CTMP). The results showed that the brightness of the bleached CTMP increased 1.5% ISO by addition of 0.1% chitosan with 95% degree of deacetylation during peroxide bleaching. Transition metals in the form of ions or metal colloid particles, such as iron, copper and manganese, could be adsorbed by chitosans. Chitosans could inhibit the decomposition of hydrogen peroxide catalyzed by different transition metals under alkaline conditions. The ability of chitosans to inhibit peroxide decomposition depended on the type of transition metals, chitosan concentration and degree of deacetylation applied. The addition of chitosan slightly reduced the concentration of the hydroxyl radical formed during the hydrogen peroxide bleaching of aspen CTMP., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Prehydrolysis of wood biomass prior to kraft cooking provides a stream containing hemicellulose-derived saccharides (HDSs) but also undesired non-saccharide compounds (NSCs) that were resulted from lignin depolymerization and carbohydrate degradation. In this study, a combined process consisting of lime treatment, resin adsorption, and gel filtration was developed to separate HDSs from NSCs. The macro-lignin impurities that accounted for 32.2% of NSCs were removed by lime treatment at 1.2% dosage with negligible HDSs loss. The majority of NSCs, lignin-derived phenolics, were eliminated by mixed bed ion exchange resin, elevating NSCs removal to 94.0%. The remaining NSCs, furfural and hydroxymethylfurfural, were excluded from HDSs by gel filtration. Chemical composition analysis showed that xylooligosaccharides (XOS) with the degree of depolymerization from 2 to 6 accounted for 28% of the total purified HDSs., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Saccharides and lignin components in prehydrolysis liquor (PHL) from kraft-based dissolving pulp production was characterized after being fractionated using membrane filtration. The results showed that the membrane filtration provided a method for organics fractionation with considerable recovery rate, but exhibited some disadvantages. Besides the limited ability in purifying oligosaccharides (OS) due to the overlaps of molecular weight distribution with lignin components, the membrane filtration could not improve the homogeneity of OS as indicated by the analysis of chemical compositions and the degree of polymerization (DP), which may be ascribed to the linear conformation of OS. The characterization of lignin components indicated a great potential for polymer industry because of the remarkable content of phenolic hydroxyl groups (PhOH), especially for low molecular weight (LMW) fraction. It was concluded the organics in PHL provided streams of value-added chemicals. However, the practical significance thereof can be realized and maximized only when they are successfully and completely fractionated., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The effects of recycling on the microstructure and properties of bleached aspen chemithermomechanical pulp (CTMP) fibres were systematically investigated. The low-temperature nitrogen adsorption and atomic force microscopy results showed that a substantial amount of large pores and most of the very small pores in the fibre wall closed and the fibre surface became less coarse and porous during recycling. The partial cocrystallisation of cellulose microfibrils took place, as reflected in the increment of the cellulose crystallinity and the width of the crystallite in the 0 0 2 lattice plane. These irreversible structural changes caused significant hornification of the recycled fibres, leading to the loss of swelling and bonding capability. The decrease of the tensile index, burst index, and tear index further demonstrated the deterioration of the fibre properties. However, the single-fibre strength considerably increased after recycling, which was mainly due to the enlarged cellulose aggregates in the fibre wall., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Based on the formation of cellulose hydrogels in NaOH/urea aqueous solvent media, cellulose self-assembly precursor is acquired. It is proved that the water uptake capability of the cellulose hydrogels depends highly on the cross-link degree (CLD) of cellulose. With varying CLD and concentration of cellulose, a variety of morphologies of cellulose self-assemblies, including sheets with perfect morphology, high-aspect-ratio fibers, and disorganized segments and network, are formed through evaporation. Furthermore, cellulose films are fabricated by diecasting and evaporating the cellulose hydrogels, resulting in a 3D-ordered structure of closely stacking of cellulose sheets. The mechanical test indicates both tensile strength and flexibility of the cellulose films are greatly improved, which is attributed to the formation of the orderly stacking of cellulose sheets. The study is expected to lay an important foundation on the preparation of ordered and high-strength cellulose materials., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The specific elimination of lignin derivatives from wood hydrolysate without sugar loss has great practical significance to biorefinery and bioenergy. In the present study, a process consisting of calcium hydroxide and anion exchange resin treatments was developed for the purpose of selective removal of lignin from wood prehydrolysis liquor (PHL). Particular emphasis was made on the ionization of phenolic lignin, and the subsequent binding to metallic salts. It was observed that phenolic hydroxyl groups (PhOH) in lignin played an important role in lignin removal. The results showed that up to 95.2% lignin was removed from PHL with 78.8% sugar recovery. This suggested that the proposed process is highly specific to lignin, and therefore can be envisaged as a great contribution to wood-sugar production or bioenergy conversion., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A precooled aqueous solution of 7 wt% NaOH/12 wt% urea was used to dissolve cellulose up to a concentration of 2 wt%, which was then coagulated in an acetone/water mixture to regenerate cellulose film. The volume ratio of acetone to water (φ) had a dominant influence on film dimensional stability, film-forming ability, micromorphology, and mechanical strength. The film regenerated at φ=2.0 showed excellent performance in both dimensional stability and film-forming ability. Compared to that from pure acetone, the cellulose film from the acetone/water mixture with φ=2.0 was more densely interwoven, since the cellulosic fibrils formed during regeneration had pores with smaller average diameter. The alkali capsulated in the film during film formation could be released at quite a slow rate into the surrounding aqueous solution. The regenerated cellulose film with adjustable structure and properties may have potential applications in drug release and ultra filtration., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Homogenous cellulose/laponite aqueous dispersions and composite films were respectively prepared from the pre-cooling NaOH/urea aqueous systems. Rheological measurements of aqueous dispersions demonstrated a sol-to-gel transition triggered by loading of laponite, reflecting a cross-linkage effect of cellulose/laponite hybrids. Similarly, based on scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) characterizations, as well as mechanical and thermal measurements, the cross-linkage effect of cellulose/laponite hybrids was also found in solid films, which played an important role in improving the tensile strength (σb) of composite films. For instance, the σb exhibited a largest enhancement up to 75.7% at a critical laponite content of 0.100 wt%, indicating that the property of composite film was closely related with the dispersion and interaction state of laponite, i.e. its content in cellulose matrix. These results were expected to provide significant information for fabrication and utility of cellulose-based materials., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Hot water extraction is an important strategy of wood fractionation, by which the hemicelluloses can be separated for value-added products, while the residual solid can still be processed into traditional wood products. In this study, a combined process consisting of specific lignin precipitation and dialysis was proposed to recover hemicellulosic oligosaccharides (OS) from hot water extract (HWE). The results showed that polyaluminium chloride (PAC) precipitation was highly specific to large molecular lignin, leading to 25.1% lignin removal with negligible OS loss through charge neutralization mechanism. The separation was further enhanced by dialysis, reaching 37.6% OS recovery from HWE with remarkable purity of 94.1%. By the proposed process, 56.36 g OS, mainly xylooligosaccharides with two fractions of 5.2 and 0.51 kDa was recovered from one kg dried wood. This process can be envisaged as a great contribution to wood biorefinery., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Thermochemical pretreatment of lignocellulose is crucial to bioconversion in the fields of biorefinery and biofuels. However, the enzyme inhibitors in pretreatment hydrolysate make solid substrate washing and hydrolysate detoxification indispensable prior to enzymatic hydrolysis. Sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) is a relatively new process, but has demonstrated robust performance for sugar and biofuel production from woody biomass in terms of yield and energy efficiency. This study demonstrated the advantage of SPORL pretreatment whereby the presentation of lignosulfonate (LS) renders the hydrolysate non-inhibitory to cellulase (Cel) due to the formation of lignosulfonate-cellulase complexes (LCCs) which can mediate the Cel adsorption between lignin and cellulose, contrary to the conventional belief that pretreatment hydrolysate inhibits the enzymatic hydrolysis unless detoxified., Results: Particular emphasis was made on the formation mechanisms and stability phase of LCCs, the electrostatic interaction between LCCs and lignin, and the redistributed Cel adsorption between lignin and cellulose. The study found that LS, the byproduct of SPORL pretreatment, behaves as a polyelectrolyte to form LCCs with Cel by associating to the oppositely charged groups of protein. Compared to Cel, the zeta potential of LCCs is more negative and adjustable by altering the molar ratio of LS to Cel, and thereby LCCs have the ability to mitigate the nonproductive binding of Cel to lignin because of the enlarged electrostatic repulsion. Experimental results showed that the benefit from the reduced nonproductive binding outweighed the detrimental effects from the inhibitors in pretreatment hydrolysate. Specifically, the glucan conversions of solid substrate from poplar and lodgepole pine were greatly elevated by 25.9% and 31.8%, respectively, with the complete addition of the corresponding hydrolysate. This contradicts the well-acknowledged concept in the fields of biofuels and biorefinery that the pretreatment hydrolysate is inhibitory to enzymes., Conclusions: The results reported in this study also suggest significant advantages of SPORL pretreatment in terms of water consumption and process integration, that is, it should abolish the steps of solid substrate washing and pretreatment hydrolysate detoxification for direct simultaneous saccharification and combined fermentation (SSCombF) of enzymatic and pretreatment hydrolysate, thereby facilitating bioprocess consolidation. Furthermore, this study not only has practical significance to biorefinery and bioenergy, but it also provides scientific importance to the molecular design of composite enzyme-polyelectrolyte systems, such as immobilized enzymes and enzyme activators, as well as to the design of enzyme separation processes using water-soluble polyelectrolytes.

Nanocrystalline cellulose (NCC) isolated from bleached aspen kraft pulp was characterized, and its application as pulp strengthening additive and retention aid was investigated. Results showed that NCC with high crystallinity of more than 80% can be obtained using 64 wt% sulfuric acid. The structure of nanocrystalline cellulose is parallelepiped rod-like, and their cross-sectional dimension is in the nanometer range with a high aspect ratio. The formation of microparticle retention systems during the application of NCC together with cationic polyacrylamide and cationic starch in deinked pulp was able to further improve pulp retention and strength properties without negative influence on the drainage., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Rejects from sulfite pulp mill that otherwise would be disposed of by incineration were converted to ethanol by a combined physical-biological process that was comprised of physical refining and simultaneous saccharification and fermentation (SSF). The energy efficiency was evaluated with comparison to thermochemically pretreated biomass, such as those pretreated by dilute acid (DA) and sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL). It was observed that the structure deconstruction of rejects by physical refining was indispensable to effective bioconversion but more energy intensive than that of thermochemically pretreated biomass. Fortunately, the energy consumption was compensated by the reduced enzyme dosage and the elevated ethanol yield. Furthermore, adjustment of disk-plates gap led to reduction in energy consumption with negligible influence on ethanol yield. In this context, energy efficiency up to 717.7% was achieved for rejects, much higher than that of SPORL sample (283.7%) and DA sample (152.8%)., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

We present a detailed study of a salt-free cationic/anionic (catanionic) surfactant system where a strongly alkaline cationic surfactant (tetradecyltrimethylammonium hydroxide, TTAOH) was mixed with a single-chain fluorocarbon acid (nonadecafluorodecanoic acid, NFDA) and a hyperbranched hydrocarbon acid [di-(2-ethylhexyl)phosphoric acid, DEHPA] in water. Typically the concentration of TTAOH is fixed while the total concentration and mixing molar ratio of NFDA and DEHPA is varied. In the absence of DEHPA and at a TTAOH concentration of 80 mmol·L(-1), an isotropic L(1) phase, an L(1)/L(α) two-phase region, and a single L(α) phase were observed successively with increasing mixing molar ratio of NFDA to TTAOH (n(NFDA)/n(TTAOH)). In the NFDA-rich region (n(NFDA)/n(TTAOH) > 1), a small amount of excess NFDA can be solubilized into the L(α) phase while a large excess of NFDA eventually leads to phase separation. When NFDA is replaced gradually by DEHPA, the mixed system of TTAOH/NFDA/DEHPA/H(2)O follows the same phase sequence as that of the TTAOH/NFDA/H(2)O system and the phase boundaries remain almost unchanged. However, the viscoelasticity of the samples in the single L(α) phase region becomes higher at the same total surfactant concentration as characterized by rheological measurements. Cryo-transmission electron microscopic (cryo-TEM) observations revealed a microstructural evolution from unilamellar vesicles to multilamellar ones and finally to gaint onions. The size of the vesicle and number of lamella can be controlled by adjusting the molar ratio of NFDA to DEHPA. The dynamic properties of the vesicular solutions have also been investigated. It is found that the yield stress and the storage modulus are time-dependent after a static mixing process between the two different types of vesicle solutions, indicating the occurrence of a dynamic fusion between the two types of vesicles. The microenvironmental changes induced by aggregate transitions were probed by (19)F NMR as well as (31)P NMR measurements. Upon replacement of NFDA by DEHPA, the signal from the (19)F atoms adjacent to the hydrophilic headgroup disappears and that from the (19)F atoms on the main chain becomes sharper. This could be interpreted as an increase of microfluidity in the mixed vesicle bilayers at higher content of DEHPA, whose alkyl chains are expected to have a lower chain melting point. Our results provide basic knowledge on vesicle formation and their structural evolution in salt-free catanionic surfactant systems containing mixed ion pairs, which may contribute to a deeper understanding of the rules governing the formation and properties of surfactant self-assembly.

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H(2)O(2), enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment.