Biodegradable, Strong, and Hydrophobic Regenerated Cellulose Films Enriched with Esterified Lignin Nanoparticles.

The scientific community is pursuing significant efforts worldwide to develop environmentally viable film materials from biomass, particularly transparent, high-performance regenerated cellulose (RC) films, to replace traditional plastics. However, the inferior mechanical performance and hydrophilic nature of RC films are generally not suitable for use as a substitute for plastics in practical applications. Herein, lignin homogenization is used to synthesize high-performance composite films. The esterified lignin nanoparticles (ELNPs) with dispersible and binding advantages are prepared through esterification and nanometrization. In the presence of ELNPs, RC films exhibit a higher tensile strength (110.4 MPa), hydrophobic nature (103.6° water contact angle, 36.6% water absorption at 120 min, and 1.127 × 10-12 g cm cm-2 s-1 Pa-1 water vapor permeability), and exciting optical properties (high visible and low ultraviolet transmittance). The films further display antioxidant activity, oxygen barrier ability, and thermostability. The films completely biodegrade at 12 and 30% soil moisture. Overall, this study offers new insights into lignin valorization and regenerated cellulose composite films as novel bioplastic materials.

Effect of Pulping Waste Liquid on the Physicochemical Properties and the Prediction Model of Wheat Straw Residue Granular Fuels.

Herein, wheat straw residue and pulping waste liquid were collected from pulping mill and mixed to prepare bio-based granular fuels by using compression molding technology, and to explore the comprehensive utilization of the industrial waste of pulping and papermaking. The effects of pulping waste liquid on granular fuel properties were analyzed systemically. Further study of the function of pulping waste liquid, cellulose and hemicellulose was used to replace wheat straw residue and avoid the interference factors. Therefore, the prediction models of granular fuels were established with influencing factors that included cellulose, hemicellulose and pulping waste liquid. The granular fuels had the best performance with 18.30% solid content of pulping waste liquid. The highest transverse compressive strength of granular fuel was 102.61 MPa, and the activation energy was 81.71 KJ·mol-1. A series of curve fitting prediction models were established to clarify the forming process of granular fuel, and it turned out that the pulping waste liquid could improve the adhesion between solid particles and increase their compression resistance.

Switchable Deep Eutectic Solvents for Lignin Dissolution and Regeneration.

Deep eutectic solvents (DESs) are promising for lignin dissolution and extraction. However, they usually possess high polarity and are difficult to recycle. To overcome this drawback, a variety of switchable ionic liquids (SILs) composed of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and alcohols was synthesized and screened. According to the thermodynamic modeling suggestions, the selected DBU-HexOH SIL was coupled with hydrogen-bond donors to form switchable-DES (SDES) systems with moderated viscosity, conductivity, and pH while maintaining switchability. The SDESs produced a well-improved lignin and lignin model compound solubility compared with those of SILs; charging CO2 into SDES (SDESCO2) caused a further increase in solubility. The solubility (25 °C) of syringic acid, ferulic acid, and milled wood lignin in SDESCO2 reached 230.57, 452.17, and 279.12 mg/g, respectively. Such SDES-dissolved lignin can be regenerated using acetone as an anti-solvent. The SDES-regenerated lignin exhibited a well-preserved structure with no noticeable chemical modifications. Furthermore, the SDESCO2 lignin possessed a higher molecular weight (Mw = 10,340 g/mol; Mn = 7672 g/mol), improved uniformity (polydispersity index = 1.35), and a higher guaiacyl lignin unit content compared with the original milled wood lignin. The SDES system proposed in the present work could benefit the fractionation of lignin compounds and facilitate downstream industrial processes.

Hollow N-doped carbon nano-mushroom encapsulated hybrid Ni3S2/Fe5Ni4S8 particle anchored to the inner wall of porous wood carbon for efficient oxygen evolution electrocatalysis.

Structural design and morphology engineering are considered significant strategies to boost the catalytic performance of electrocatalysts toward the oxygen evolution reaction. Inspired by the natural porosity and abundant functional groups, herein, hollow N-doped carbon nano-mushroom (NCNM) encapsulated hybrid sulfide particles rooted into a carbonized wood (CW) framework were prepared through simple impregnation followed by calcination. The as-prepared self-supporting electrodes present ultrahigh activity and robust stability. Among them, the NiFeS14@NCNM/CW catalyst yields incredible OER activity with an extraordinarily low overpotential of 147 and 250 mV to reach 10 and 50 mA cm-2, respectively, superior to most of the state-of-the-art wood-derived electrocatalysts. Additionally, a steady OER current density is maintained without obvious attenuation after continuous operation for 24 h. The superior electrocatalytic performance of NiFeS14@NCNM/CW is attributed to the synergistic effect of hybridization between Ni3S2 and Fe5Ni4S8, the coordination of one-dimensional (1D) NCNMs and hierarchical three-dimensional (3D) porous CW, modified electronic states by N and S doping, a large electrochemical surface area, and low activation energy. This research provides a novel approach to industrial-scale conversion of abundant biomass into efficient binder-free electrocatalysts for energy-related applications.

Recent advances in sustainable preparation of cellulose nanocrystals via solid acid hydrolysis: A mini-review.

As a green and renewable nanomaterial, cellulose nanocrystals (CNC) have received numerous attention due to the unique structural features and superior physicochemical properties. Conventionally, CNC was isolated from lignocellulosic biomass mostly depending on sulfuric or hydrochloric acid hydrolysis. Although this approach is effective, some critical issues such as severe equipment corrosion, excessive cellulose degradation, serious environmental pollution, and large water usage are inevitable. Fortunately, solid acid hydrolysis is emerging as an economical and sustainable CNC production technique and has achieved considerable progress in recent years. Herein, the preparation of CNC by solid acid hydrolysis was summarized systematically, including organic solid acids (citric, maleic, oxalic, tartaric, p-toluenesulfonic acid) and inorganic solid acids (phosphotungstic, phosphoric, and Lewis acid). The advantages and disadvantages of organic and inorganic solid acid hydrolysis methods were evaluated comprehensively. Finally, the challenges and opportunities in the later exploitation and application of solid acid hydrolysis to prepare CNC in the industrial context are discussed. Considering the future development of this technology in the large-scale CNC production, much more efforts should be made in lowering CNC processing cost, fabricating high-solid-content and re-dispersible CNC, developing value-added applications of CNC, and techno-economic analysis and life cycle assessment on the whole process.

Controlling the nanocellulose morphology by preparation conditions.

Nanocellulose (NC) is the desired building block for novel biomaterials. The morphology of NC is one of the core parameters impacting the functionality and property of engineered functional materials. This work aims to reveal the relationship between the product morphology and sulfuric acid hydrolysis conditions (including acid concentration, temperature and time), and to realize morphological regulation of obtained NC. Three representative products were obtained from microcrystalline cellulose via sulfuric acid hydrolysis, which are cellulose nanocrystals with broad size distribution (W-CNC, 383.9 ± 131.7 nm in length, 6 ± 2.1 nm in height) obtained by 61 % H2SO4, 55 °C and 90 min, cellulose nanospheres (CNS, 61.3 ± 15.9 nm in diameter) obtained by 64 % H2SO4, 35 °C and 75 min, and CNC with narrow size distribution (N-CNC, 276.1 ± 28.7 nm in length, 4.1 ± 0.6 nm in height), obtained by 64 % H2SO4, 45 °C and 45 min. The results showed that the crystallographic form of W-CNC and N-CNC are cellulose I, while cellulose I and II coexist in CNS. Only W-CNC and N-CNC can form chiral nematic structures through evaporation-induced self-assembly strategy and reflected light with specific wavelengths. In addition, the formation mechanism of CNS with cellulose I/II was proposed, which provided a better understanding of NC morphology regulation.

Preparation of Dissolving Pulp by Combined Mechanical and Deep Eutectic Solvent Treatment.

Grasses are potential candidate to replace wood as a raw material for pulping and paper making, and several processes have been developed to produce grass pulp. In this study, wheat straw was used as raw material, and the possibility of sequential treatment with a mechanical method and deep eutectic solvent (DES) to prepare high-quality dissolving pulp was explored. Firstly, the wheat straw was mechanically treated, and then the wheat straw was delignified using a choline chloride-lactic acid deep eutectic solvent. The results showed that the optimal treatment conditions of deep eutectic solvent were 110 °C, 6 h, and a solid-liquid ratio (ratio of pulp to DES) of 1:40. The removal rate of lignin was 82.92%, the glucose content of pulp was increased by 11.42%. The DES recovery rate was further calculated, and the results showed that the DES recovery rate was more than 50% with rotary evaporation. The pulp viscosity after bleaching was 472 mL/g, and the α-cellulose accounted for 81.79%. This treatment has advantages in biomass refining, and the total utilization rate of wheat straw reaches 72%. This study confirmed that combined mechanical and deep eutectic solvent treatment can effectively remove lignin from wheat straw to produce high-quality wheat straw dissolving pulp.

In situ growth of a cobalt porphyrin-based covalent organic framework on multi-walled carbon nanotubes for ultrasensitive real-time monitoring of living cell-released nitric oxide.

Nitric oxide (NO), as a critical transcellular messenger, participates in a variety of physiological and pathological processes. However, its real-time detection still faces challenges due to its short half-life and trace amounts. Here, MWCNTs@COF-366-Co was prepared by in situ growth of a cobalt porphyrin-based covalent organic framework (COF-366-Co) on multi-walled carbon nanotubes (MWCNTs), and a unique biosensing platform for ultrasensitive real-time NO determination was established. Remarkably, MWCNTs@COF-366-Co contains plenty of atomically arranged M-N4 active sites for electrocatalysis, which provides more efficient electron transfer pathways and resolves the random arrangement issue of active sites. COF-366-Co with a high surface area contains a large number of exposed active M-N4 sites, providing faster NO transport/diffusion and more efficient electron transfer pathways. Due to the synergy of atomic-level periodic structural features of COF-366-Co and high conductivity of MWCNTs, the MWCNTs@COF-366-Co electrochemical biosensor exhibited excellent NO determination performance in a wide range from 0.09 to 400 µM, with high sensitivity (8.9 µA µM-1 cm-2) and a low limit of detection (16 nM). Moreover, the biosensor has been successfully used to sensitively monitor NO molecules released from human umbilical vein endothelial cells (HUVECs). This research not only designed a multifunctional intelligent biosensor platform, but also provided a broad prospect for continuous dynamic monitoring of the activity of living cells and their released metabolites.

Structural regulatory mechanism of phosphotungstate acid decorated graphene oxide quantum dots-chitosan aerogel and its application in ciprofloxacin degradation.

Chitosan modified AGQD (amine modified graphene oxide quantum dots) and then combined with H3PW12O40 to obtain CSx@AGQD-HPW12 via facile process and applied for CIP removal through pre-adsorption and photocatalytic processes. The application of chitosan could regulate the morphology and photoelectric properties effectively. CS0.5@AGQD-HPW12 was found to have the optimal CIP removal performance among all the products, the corresponding adsorption removal efficiency and pre-adsorption photocatalysis process were 72.1 % and 98.8 %, respectively. Results of toxicity assessment confirmed photocatalytic degradation process could mitigate the ecotoxicity of CIP effectively. The optimal TOC (total organic carbon) removal efficiency was about 52.1 %. Possible pathways for CIP degradation and reaction mechanism were proposed based on the results of intermediates analysis and trapping experiments. This demonstrated a novel approach to chitosan application and an eco-friendly way to remove CIP by adsorption-photocatalysis process.

Corn stalk modified chitin composite sponge for effective hemostasis and promoting wound healing.

The hemorrhage in daily life was a great challenge for the life health. Before hospitalization and infection, stopping traumatic bleeding timely is an important measure to decrease the death threat. The high crystallinity and low porous structure of chitin (CH) make texture of sole CH sponge not soft enough, which limit its hemostatic properties. In this work, loose corn stalk (CS) was used to modify the structures and properties of sole CH sponge. The novel hemostatic composite sponge of CH/CS4 was prepared by cross-linking and freeze-drying process of chitin and corn stalk suspension. The composite sponge obtained best physical and hemostatic properties at the 1:1 volume ratio of chitin and corn stalk. Thanks to the porous structures, CH/CS4 possessed high water/blood absorption ability (34 ± 2 g/g and 32.7 ± 2 g/g), rapid hemostatic time (31 s) and low blood loss (0.31 g), allowing it to be delivered into the wound bleeding sites to reduce the wound bleeding by robust physical barrier and pressure effect. Furthermore, CH/CS4 displayed excellent hemostatic performance than sole CH and commercial polyvinyl fluoride sponge (PVF). Moreover, CH/CS4 displayed superior wound healing ability and cytocompatibility. Therefore, the CH/CS4 has high potential application in medical hemostatic field.

A morphology control engineered strategy of Ti3C2Tx/sulfated cellulose nanofibril composite film towards high-performance flexible supercapacitor electrode.

2D Ti3C2Tx MXene is an ideal material for fabricating supercapacitor electrodes due to its excellent physical-chemical properties. However, the inherent self-stacking, narrow interlayer spacing, and low general mechanical strength limit its application in flexible supercapacitors. Herein, facile structural engineering strategies by drying (vacuum drying, freeze drying, and spin drying) were proposed to fabricate 3D high-performance Ti3C2Tx/sulfated cellulose nanofibril (SCNF) self-supporting film supercapacitor electrodes. Compared with other composite films, the freeze-dried Ti3C2Tx/SCNF composite film exhibited a looser interlayer structure with more space which was conducive to charge storage and ion transport in the electrolyte. Therefore, the freeze-dried Ti3C2Tx/SCNF composite film exhibited a higher specific capacitance (220 F/g) compared to the vacuum-dried Ti3C2Tx/SCNF composite film (191 F/g) and the spin-dried Ti3C2Tx/SCNF composite film (211 F/g). After 5000 cycles, the capacitance retention rate of the freeze-dried Ti3C2Tx/SCNF film electrode was close to 100 %, showing excellent cycle performance. Meanwhile, the tensile strength of freeze-dried Ti3C2Tx/SCNF composite film (13.7 MPa) was much greater than that of the pure film (7.4 MPa). This work demonstrated a facile strategy for control of Ti3C2Tx/SCNF composite film interlayer structure by drying for fabricating well-designed structured flexible and free-standing supercapacitor electrodes.

Application effect of multi-slice spiral CT angiography combined with MRI in the diagnosis of cerebral aneurysm.

To investigate the clinical value of multi-slice spiral computed tomography (CT) angiography (MSCTA) combined with MRI in the diagnosis of cerebral aneurysm. A total of 90 patients with cerebral aneurysms diagnosed by DSA were selected as the subjects of this study. Another 30 patients with cerebral infarction were selected as negative controls (NC). Before diagnosis, all patients underwent comprehensive examination using MSCTA and MRI. The results of the comparison and the clinical data of all patients were retrospectively analyzed. MSCTA and MRI examinations can clearly show the specific location, shape, size and anatomical relationship with surrounding tissues of cerebral aneurysms. MSCTA diagnosed 82 patients and missed or misdiagnosed 8 patients in the 90 patients with cerebral aneurysm. The diagnostic sensitivity and accuracy of MSCTA were 91.1 (82/90) and 89.2 (107/120), respectively. MRI examination diagnosed 87 patients and missed or misdiagnosed 3 patients in the 90 patients with cerebral aneurysm. The diagnostic sensitivity and accuracy of MRI were 96.7 (87/90) and 96.7 (116/120), respectively. The sensitivity and accuracy of MSCTA combined with MRI were 100.0 (90/90) and 99.2 (119/120), respectively. MSCTA combined with MRI can not only display the whole picture of brain tissue, but also display the size, shape and relationship with the parent vessel of the aneurysm. The combination of MSCTA and MRI has high sensitivity and accuracy in diagnosing intracranial aneurysms, which provides a promising diagnostic protocol for patients with aneurysms.

Facile sulfation of cellulose via recyclable ternary deep eutectic solvents for low-cost cellulose nanofibril preparation.

Here we present a new method to treat cellulose with a sulfamic acid-urea-choline chloride (ternary deep eutectic solvent) system, which can realize both swelling and sulfation of cellulose. This can greatly reduce the energy consumption in the process of cellulose nanoization, and use it to successfully prepare food packaging films for eliminating odors. We hope that due its simplicity and resource-efficiency, this method will have a widespread influence on currently used (nano) cellulose modification protocols.

Biomass-Based Hydrothermal Carbons for the Contaminants Removal of Wastewater: A Mini-Review.

The preparation of adsorbents with eco-friendly and high-efficiency characteristics is an important approach for pollutant removal, and can relieve the pressure of water shortage and environmental pollution. In recent studies, much attention has been paid to the potential of hydrothermal carbonization (HTC) from biomass, such as cellulose, hemicellulose, lignin, and agricultural waste for the preparation of adsorbents. Hereby, this paper summarizes the state of research on carbon adsorbents developed from various sources with HTC. The reaction mechanism of HTC, the different products, the modification of hydrochar to obtain activated carbon, and the treatment of heavy metal pollution and organic dyes from wastewater are reviewed. The maximum adsorption capacity of carbon from different biomass sources was also evaluated.

Nanogrinding/ethanol activation facilitating lignin fractionation for preparation of monodispersed lignin nanoparticles.

Lignin nanoparticles (LNPs), as one of green and sustainable biological macromolecules, have attracted great attention owing to their promising potentials in many valorized fields. However, the lignin heterogeneity seriously restricts the controllable preparation of LNPs. Herein, a facile nanogrinding activation combining anhydrous ethanol dissolution process was developed to efficiently homogenize lignin prior to gradient ethanol fractionation. Two lignin fractions were obtained from nanogrinding activation/ethanol dissolution followed by gradient ethanol fractionation: L-fractions and S-fractions. Therefore, monodispersed LNPs with unique concave hollow nanostructure and large particle size, and monodispersed LNPs with solid core nanostructure and small particle size were successfully prepared from L-fractions and S-fractions, respectively, via a GVL/water anti-solvent method. The proposed LNPs formation mechanisms facilitated by nanogrinding activation/ethanol dissolution treatment were demonstrated. This study put forwards a facile and green integrated approach for monodispersed LNPs preparation with controllable morphology and particle size.

Preparation of ultrafine and highly loaded silver nanoparticle composites and their highly efficient applications as reductive catalysts and antibacterial agents.

The size of silver nanoparticles (Ag NPs) and loading amount of Ag NPs onto their substrate/carrier are two key factors for their efficient applications. Herein, we present a facile method for in situ synthesizing ultrafine and highly loaded Ag NPs on the surface of tannin-coated catechol-formaldehyde resin (TA-CFR) nanospheres. TA-CFR nanospheres act as green and highly efficient reducing agents for converting silver ions (Ag+) into Ag NPs, and the size of resultant Ag NPs is only âˆ¼ 7.5 nm, and the Ag NPs loading capacity of TA-CFR is as high as 61.5 wt%, both of which contribute to the very high specific surface area of Ag NPs. Consequently, the as-synthesized TA-CFR@Ag composites show high catalytic performance, and the catalytic rate for the reduction of 4-nitrophenol is almost 10 times higher than that of the control. Meanwhile, TA-CFR@Ag composites also possess high antibacterial activity, efficiently inhibiting the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, tannin coating (thickness: ∼ 15 nm) minimizes the aggregation of Ag NPs, and enhances the reusability and stability of resultant Ag NPs, because of their high surface charges (the zeta potential is up to -65.5 ± 1.9 mV) and strong coordination capability with Ag NPs. This work provides a new frontier to develop multifunctional nanomaterials focusing on the green catalyst synthesis and environmental-remedy applications.

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

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.

Effects of Lipase and Xylanase Pretreatment on the Structure and Pulping Properties of Wheat Straw.

Based on the reduction of environmental pollution, a biological enzyme assisted alkali-oxygen pulping method was explored to improve the delignification efficiency and fiber accessibility of wheat straw and improve the properties of wheat straw pulp. In this paper, lipase and xylanase were used to pretreat wheat straw and the effects of different enzyme types and enzyme dosage on the microstructure and pulp properties of wheat straw were investigated and experimented. The results showed that the lipase can remove fat and wax on the surface of wheat straw, while xylanase degraded the hemicellulose components, such as xylan, of wheat straw fiber, destroyed the structure of the lignin-carbohydrate complex, increasing lignin removal as a result and enhancing the impregnating, diffusion and penetration of alkali. Compared with wheat straw without enzyme pretreatment, the skeleton of wheat straw pretreated by enzyme became looser, the internal cavity appeared and the wall cavity became thin and transparent. The fines decreased obviously and the length of fibers increased. After combined pretreatment with lipase (15 U·g-1) and xylanase (15 U·g-1), the pulping performance of wheat straw was improved and the tensile index (97.37 N·m·g-1), brightness (40.9% ISO) and yield (58.10%) of the pulp increased by 12.9%, 19.9% and 9.9%, respectively. It can be seen that enzyme pretreatment is a green and effective approach to improving the alkali-oxygen pulping performance of wheat straw.

Polyphosphazene-Functionalized Microspheres as Efficient Catalysts for the Knoevenagel Reaction under Mild Conditions.

Inspired by the formation of microspheres by hexachlorocyclotriphosphazene and 4, 4'-sulfonyldiphenol, polyphosphazene-functionalized microspheres were developed. Benefits from the supported supper basic phosphazene, the yield exceeded 99 % at room temperature in the manner of second-order reaction kinetics toward Knoevenagel reaction and was still maintained at 99 % after 16 runs. In the experimental temperature from 0 °C to 90 °C, the yield increased from 92 % to 99 %, reflecting that the catalyst had strong applicability under mild conditions. This behavior was conducive to energy conservation. Meanwhile, simple separation and recovery further enhanced this advantage. In addition, the catalyst was also found to be insensitive to aqueous solution or organic solvents such as toluene, THF, EtOH and CH3 CN. This property gave the Knoevenagel reaction a vast choice. All these features exhibit that this novel catalyst is an attractive and applicable alternative in organic synthesis.

Recent advanced application of lignin nanoparticles in the functional composites: A mini-review.

In recent years, lignin nanoparticles (LNP) have gained tremendous and deep research in the field of functional composites because of their many advantages such as abundant, non-toxic, affordable, green, eco-friendly, biodegradable and biocompatible features along with antioxidant, antibacterial and UV-absorbing abilities. At present, numerous pioneering works have been devoted to the development of LNP-based composites with multiple functions. Herein, we comprehensively reviewed the latest research progress correlated with LNP-filled functional composites. This overview focused on the application of LNP as reinforcement, crosslinker, UV-protectant, antioxidant, antimicrobial and adhesive agents for functional composites. Additionally, the challenges and future outlooks for further exploiting and utilization of LNP in the functional composites were discussed.