Lignin Matrix Research Articles

Lignin hygroexpansion in compression and opposite wood - a molecular dynamics study

Softwood branches develop compression wood (CW) in the lower parts of the branch, while opposite wood (OW) develops on the upper. These wood types differ in structure at several length scales, among others in the chemical composition of their lignin matrix. While OW mostly contains guaiacyl (G) units, CW is known to contain a substantial fraction of 4-hydroxyphenyl (H) lignin. In this study, the impact this difference has on lignin hygroexpansion and interaction with water is studied by the means of atomistic models and molecular dynamics computer simulations of lignin systems at different levels of hydration. It was found that, despite the minor difference in chemical composition, there are differences in swelling, structure and water dynamics. CW lignin is found to have a higher uniaxial swelling coefficient, since the phase separation between lignin and water is more pronounced. This behavior is linked to structural differences, where intermolecular π-π stacking is more common in CW lignin and hydrogen bonding to water more pronounced in OW lignin. These findings are of interest for understanding the role of lignin in CW, and general understanding of moisture interaction with lignin inside wood cell walls.

Improved Graphitization of Lignin by Templating Using Graphene Oxide Additives.

Techniques to improve the graphitization of lignin, the second most abundant natural polymer, are in great demand as a viable means to obtain cost-effective and less energy-intensive graphite for various applications. In this work, we report the effects of two-dimensional nanomaterials, graphene oxide (GO) and its derivative, reduced graphene oxide (RGO), used as templating agents for the graphitization of alkali-derived lignin. The hypothesis is that during heat temperature treatment, the GO additives act as a template that allows the lignin matrix to align on its basal planes through π-π interactions. In addition, possible chemical bonding between the GO additives and lignin may extend the two planar frameworks. Results from X-ray diffraction and Raman spectroscopy showed improved graphitic quality in the lignin-GO and lignin-RGO samples compared to pure lignin at 2500 °C. Transmission electron microscopy images and selected area electron diffraction patterns also revealed ordered nanostructures and defined polycrystalline patterns in the lignin-GO and lignin-RGO samples. This work presents a method to synthesize graphitic-like materials using carbon-based templates with the advantage that there is no need for further purification of the final material as in the case of transition metal catalysts.

Statistical optimisation of enzymatic pre-treatment process of marigold flower waste for enhanced hydrolysis and complete release of lutein ester through Taguchi orthogonal design

ABSTRACT The lutein ester of the marigold flower is entrapped in the matrix of pectin, cellulose, hemicellulose and lignin which cannot be released by moderate acidic, alkaline treatment or enzymatic treatment with a single enzyme. Five different parameters are optimized in the current study for two response factors: lutein ester extraction (LEEP) and floral solid hydrolyzed percentage (FSHP). Three commercially available enzymes, namely pectinase, cellulase, and xylanase, at various temperatures and time intervals were utilised to optimise the enzymatic hydrolysis of flower biomass. An L27 orthogonal Taguchi experimental design was employed, investigating temperature (25–35 °C), time (10–30 days), and enzyme levels (pectinase, cellulase and xylanase at 0–1 mL). The optimal conditions for 100% lutein ester extraction from marigold flower waste were: temperature 35 °C, 20 days, and enzymes 1 mL/200 g each of pectinase (2600 µPG/g), cellulase (20000 CMC U/g), and xylanase (300000 U/g). Thus, it could be concluded that optimisation by the Taguchi method could be used to develop an enzyme cocktail for the hydrolysis of marigold flowers to obtain the best yield of lutein ester. The aim is to enhance the yield of lutein ester through the optimisation of the enzymatic pre-treatment of the marigold flower.

Modulation of improved lignin structure for conversion of iron oxides on the metal artifact

This research reveals the structural analysis and antioxidant properties of unmodified ethanol organosolv lignin (AH EOL) and modified ethanol organosolv lignin (AHD EOL and AHPB EOL) upon incorporation with 1,5-dihydroxy naphthalene and p-benzoquinone, respectively. The extracted lignin derived from OPF was then evaluated with FTIR NMR, GPC, thermal analyses (TGA and DSC), solubility test, and antioxidant activity. Modified ethanol organosolv lignin incorporated with p-benzoquinone (AHPB EOL) exhibited the smallest lignin matrix, which leads to the highest water solubility and antioxidant activity compared to other ethanol organosolv lignin (EOL) samples (D% AHPB EOL: 24.25 ± 0.13 % > D% AHD EOL: 22.50 ± 0.16 % > D% AH EOL: 20.50 ± 0.22 %). The extracted EOL samples derived from OPF were then utilized in a preliminary rust conversion study of a metal artifact, which indicated that 7 wt% AHPB EOL possessed the highest RT% with 88.81 ± 0.14 %. The XRD and surface analysis of the treated rust also showed that it had transformed the archeological rust into an amorphous phase.

‘Rigid–flexible’ strategy for high-strength, near-room-temperature self-healing, photo-thermally functionalised lignin-reinforced polyurethane elastomers

Lignin is the most abundant and only renewable aromatic polymer in nature. Herein, a flexible matrix and the rigid lignin were rationally integrated to prepare high-strength, near-room-temperature self-healing, processable lignin-reinforced polyurethane elastomers (LZPUs). Reversible hydrogen and oxime–amino ester bonds were introduced into the matrix to provide excellent dynamic properties and abundant ligands for lignin–matrix coordination bonds. Abundant metal coordination bonds were constructed between the matrix and lignin via the introduction of Zn2+, which not only effectively enhances the dispersibility and compatibility, but also provides an excellent energy dissipation mechanism for the LZPUs. One of the prepared elastomers, LZPUs, exhibited a high strength of 40.5 MPa, which is twice that of the blank sample and 1.6 times that of the sample without Zn2+. It maintained kinetic stability at mild temperature, but it exhibited a self-healing efficiency of 91.3 % in strength and 99.8 % in elongation at break after decoupling with trace ethanol (≈ 50 μL) at 35 °C. It exhibited a self-healing efficiency of 93.6 % in strength under 1 sun irradiation (0.1 W cm−2) for 4 h. We believe this elastomer offering high mechanical properties with multi-functionality can be applied in flexible drives and photo-thermal power generation.

Lignin nanoparticle as a vehicle to load, release, and improve the stability and antioxidant activity of curcumin: Comparison between dropping and pouring regimes

Curcumin (Cur) was loaded in lignin nanoparticles (LNP) via an antisolvent method by pouring (P-) and dropping (D-) regimes, respectively, and Cur-loaded LNP (Cur/LNP) were comparatively characterized. The results indicated that P-Cur/LNP (62–92 nm) was much smaller than D-Cur/LNP (134–139 nm). For both regimes, their maximum loading efficiencies were comparable (91 ± 3%), while dropping regime (236.2 mg/g) demonstrated a higher loading capacity than pouring regime (174.6 mg/g). In both regimes, Cur was loaded in an amorphous form via the hydrophobic, hydrogen-bonding, and π-π interactions with lignin matrix and it demonstrated a controlled release in in vitro digestion test. In comparison, Cur in D-Cur/LNP showed higher stabilities against photodegradation, thermal treatment, and 30-d storage than that in P-Cur/LNP, while P-Cur/LNP concluded a higher antioxidant activity than D-Cur/LNP. The present findings attested that LNP was a valuable tool to stabilize and controlled release of lipophilic phytochemicals as well as improve their bioactivities.

Silica Biomineralization with Lignin Involves Si-O-C Bonds That Stabilize Radicals.

Plants undergo substantial biomineralization of silicon, which is deposited primarily in cell walls as amorphous silica. The mineral formation could be moderated by the structure and chemistry of lignin, a polyphenol polymer that is a major constituent of the secondary cell wall. However, the reactions between lignin and silica have not yet been well elucidated. Here, we investigate silica deposition onto a lignin model compound. Polyphenyl propanoid was synthesized from coniferyl alcohol by oxidative coupling with peroxidase in the presence of acidic tetramethyl orthosilicate, a silicic acid precursor. Raman, Fourier transform infrared, and X-ray photoelectron spectroscopies detected changes in lignin formation in the presence of silicic acid. Bonds between the Si-O/Si-OH residues and phenoxyl radicals and lignin functional groups formed during the first 3 h of the reaction, while silica continued to form over 3 days. Thermal gravimetric analysis indicated that lignin yields increased in the presence of silicic acid, possibly via the stabilization of phenolic radicals. This, in turn, resulted in shorter stretches of the lignin polymer. Silica deposition initiated within a lignin matrix via the formation of covalent Si-O-C bonds. The silica nucleants grew into 2-5 nm particles, as observed via scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. Additional silica precipitated into an extended gel. Collectively, our results demonstrate a reciprocal relation by which lignin polymerization catalyzes the formation of silica, and at the same time silicic acid enhances lignin polymerization and yield.

Thermogravimetric investigation of anisotropy of dimensional shrinkage of softwood and hardwood during carbonization

Thermogravimetric analysis (TGA) was performed on five softwood and five hardwood thin wood samples in the longitudinal (L) and radial (R) directions. Dimensional changes were monitored using a charge-coupled device camera under a nitrogen flow. A comparison of the TG and derivative TG (DTG) curves revealed that shrinkage in the R direction began when the weight was reduced to 79–92% at 305–330 °C and 87–96% at 275–290 °C for softwoods and hardwoods, respectively. Hemicellulose is mainly degraded in this temperature range. In contrast, shrinkage in the L direction started at temperatures close to the DTG peaks, i.e., 360–380 °C and 345–370 °C, respectively, at which temperatures cellulose is mainly degraded. In general, the R/L shrinkage anisotropy was greater for hardwoods than for softwoods, but the species variation was large and the magnitude was directly related to the difference in the shrinkage onset temperatures between the R and L directions, regardless of the wood species. Therefore, shrinkage anisotropy can be attributed to the relative reactivity of hemicellulose and cellulose in wood cell walls. The shrinkage mechanism during carbonization is discussed in terms of the cell wall ultrastructure, in which cellulose microfibrils are covered by a hemicellulose–lignin matrix, and the orientation of the cells in the L and R directions.

Cell wall water induced dimensional changes of beech and pine wood

Hygroexpansion in timber construction is a phenomenon that occurs as a result of changes in the cell wall structure of wood caused by water. In this study, beech (Fagus sylvatica) and pine (Pinus taeda L.) wood were conditioned at different relative humidities with saturated salt solutions and saturated through vacuum pressure impregnation. The moisture content and dimensions of the samples were evaluated under various adsorption equilibrium states, as well as during drying from water saturation to an air-dried state. The results obtained using the two-dimensional time-domain nuclear magnetic resonance technique revealed two distinct types of cell wall water in both wood species, designated as B-water and C-water, as they displayed different mobilities. With increasing moisture content, the mobility of cell wall water increased; however, B-water maintained a constant level of mobility and formed water clusters when it accumulated in the high humidity region and at slightly above the fiber saturation point (FSP), which is evidence of the occurrence of free-bound water. The B-water, located in the amorphous region of microfibrils and their surrounding hemicellulose, exerted a predominant influence on the dimensional changes of the wood both under equilibrium and nonequilibrium conditions, in comparison to the C-water which located in the matrix of hemicellulose and lignin.

Investigation of chemical, physical and morpho-mechanical properties of banana-plantain stalk fibers for ropes and woven fabrics used in composite and limited-lifespan geotextile

This study aimed to assess the potential of banana-plantain stalk fibers (BPSF) as a raw material for ropes and fabrics used in composites and geotextiles. Fibers were obtained by Biological retting and ropes used for geotextile weaving were obtained by three-strand twisting in order to optimize the mechanical properties of geostalk. The thermal, physical, chemical and mechanical characteristics of the fibers were studied in order to assess the impact of the extraction process on fiber performance. In addition, the microstructure of fibers and ropes was analyzed using Scanning Electron Microscopy (SEM) and the results highlighted the presence of cellulose microfibrils parallel to fiber axis and hemicellulose linked by lignin matrix. These constituents are organized in three concentric layers around the lumen. Elementary chemical analyses using X-ray energy dispersion (EDS), Fourier Transform Infrared (FTIR) and chemical deconstruction using Jayme-Wise protocol were carried out to determine the chemical composition of BPSF, which consists of 51.5 % Carbon, 47.07 % Oxygen and mineral salts that can be highly contribute to soil fertilization after degradation. These chemical constituents represent 40 % cellulose, 21.5 % hemicellulose, 24 % lignin, 0.34 % pectin, 7.2 % lip soluble extractable and 7.36 % water-soluble sugars present in BPSF. Thermal properties of BPSF have been investigated showing the initial degradation around 200 °C. Physical analysis and uniaxial tensile testing were performed to determine the multi-scale physical and mechanical properties of geostalk. Statistical evaluation using Weibull distribution established an increasing rate of physical and mechanical properties from the finest scale to the macroscopic scale. Thus, from the BPSF to the ropes, titer increases from 42.5 ± 4.5 g/km to 7983.4 ± 132 g/km and elongation at break increases from 0.75 ± 0.29 mm for the fibers to 52.42 ± 18.91 mm for geostalk. With mass per unit area of 1869 g/m2, the tensile stress of 1281.05 ± 273 MPa and maximum strength of 15.4 ± 1.74 kN/m, geostalk is a sustainable woven fabric alternative to geosynthetics for soil reinforcement as other limited lifespan geotextiles (geojute, geocoir and geosisal). In addition, the thermal stability and high mechanical properties of fibers and ropes suggest their potential application as reinforced phases in composite materials.

Characterization of Densified Pine Wood and a Zero-Thickness Bio-Based Adhesive for Eco-Friendly Structural Applications.

This study investigates a sustainable alternative for composites and adhesives in high-performance industries like civil and automotive. This study pioneers the development and application of a new methodology to characterize a bio-based, zero-thickness adhesive. This method facilitates precise measurements of the adhesive's strength and fracture properties under zero-thickness conditions. The research also encompasses the characterization of densified pine wood, an innovative wood product distinguished by enhanced mechanical properties, which is subsequently compared to natural pine wood. We conducted a comprehensive characterization of wood's strength properties, utilizing dogbone-shaped samples in the fiber direction, and block specimens in the transverse direction. Butt joints were employed for adhesive testing. Mode I fracture properties were determined via compact tension (CT) and double cantilever beam (DCB) tests for wood and adhesive, respectively, while mode II response was assessed through end-loaded split (ELS) tests. The densification procedure, encompassing chemical and mechanical processes, was a focal point of the study. Initially, wood was subjected to acid boiling to remove the wood matrix, followed by the application of pressure to enhance density. As a result, wood density increased by approximately 100 percent, accompanied by substantial improvements in strength and fracture energy along the fiber direction by about 120 percent. However, it is worth noting that due to the delignification nature of the densification method, properties in the transverse direction, mainly reliant on the lignin matrix, exhibited compromises. Also introduced was an innovative technique to evaluate the bio-based adhesive, applied as a zero-thickness layer. The results from this method reveal promising mechanical properties, highlighting the bio-based adhesive's potential as an eco-friendly substitute for synthetic adhesives in the wood industry.

Cashew Nutshells: A Promising Filler for 3D Printing Filaments.

Cashew nutshells from the northern region of Colombia were prepared to assess their potential use as a filler in polymer matrix filaments for 3D printing. After drying and grinding processes, cashew nutshells were characterized using scanning electron microscopy (SEM), attenuated total reflectance Fourier-transform infrared (ATR-FTIR), and thermogravimetric analyses (TGA). Three different filaments were fabricated from polylactic acid pellets and cashew nutshell particles at 0.5, 1.0, and 2.0 weight percentages using a single-screw extruder. Subsequently, single-filament tensile tests were carried out on them. SEM images showed rough and porous particles composed of an arrangement of cellulose microfibrils embedded in a hemicellulose and lignin matrix, the typical microstructure reported for natural fibers. These characteristics observed in the particles are favorable for improving filler-matrix adhesion in polymer matrix composites. In addition, their low density of 0.337 g/cm3 makes them attractive for lightweight applications. ATR-FTIR spectra exhibited specific functional groups attributed to hemicellulose, cellulose, and lignin, as well as a possible transformation to crystalline cellulose during drying treatment. According to TGA analyses, the thermal stability of cashew nutshell particles is around 320 °C. The three polylactic acid-cashew nutshell particle filaments prepared in this work showed higher tensile strength and elongation at break when compared to polylactic acid filament. The characteristics displayed by these cashew nutshell particles make them a promising filler for 3D printing filaments.

A 3D multi-scale hygro-mechanical model of oak wood

A multi-scale framework is proposed for the prediction of the macroscopic hygro-elastic properties of oak wood. The distinctive features of the current multi-scale approach are that: (i) Four different scales of observation are considered, which enables the inclusion of heterogeneous effects from the nano-, micro-, and meso-scales in the effective constitutive behavior of oak at the macro-scale, (ii) the model relies on three-dimensional material descriptions at each considered length scale, and (iii) a moisture-dependent constitutive assumption is adopted at the nano-scale, which allows for recovering the moisture dependency of the material response at higher scales of observation. In the modeling approach, oak wood is assumed as homogeneous at the macro-scale. The meso-scale description considers the cellular structure of individual growth rings with three different densities. At the micro-scale, the heterogeneous nature of cell walls is described by the characteristics of the primary and secondary cell wall layers. Finally, the nano-scale response is determined by cellulose micro-fibrils embedded in a matrix of hemicellulose and lignin. The oak properties at the four length scales are connected via a three-level homogenization procedure, for which, depending on the geometry of the fine-scale configuration, an asymptotic homogenization procedure or Voigt averaging procedure is applied at each level to determine the effective hygro-elastic properties at the corresponding coarse scale. In addition, the moisture adsorption isotherms at each scale are constructed from a volume-weighted averaging of the moisture adsorption characteristics at the scale below. The computational results demonstrate that the macro-scale moisture-dependent, hygro-elastic behavior of oak wood is predicted realistically, thereby revealing the influence of the material density, the micro-fibril orientation, and the hygro-elastic properties from the underlying scales. The computed macro-scale properties of oak are in good agreement with experimental data reported in the literature.

Mechanistic insights into the cinnamaldehyde modification of lignin for sustainable anti-fungal reagent

The limited anti-fungal activity of enzymatic hydrolysis lignin (EHL) has been a challenge in its direct application as a bamboo preservative. To address this issue, the cinnamaldehyde modification of EHL was carried out to introduce anti-fungal structures into the lignin matrix, effectively enhancing its anti-fungal activity. The results demonstrated that the minimal inhibitory concentrations of the modified lignin (EHL-DC) against Aspergillus niger significantly improved from 16 mg/mL to 1 mg/mL, with comparable enhancements in anti-fungal activity against other fungi. As a result of the modification, the EHL-DC is more prone to interact with fungal cell membranes, contributing to a roughened, shrunken hyphal surface and a decrease in mycelial biomass. Multiple characterization methods were employed to better grapple with the EHL-DC chemical changes. The nitrogen content increased from 2.3 % to 8.3 %, and alterations in elemental compositions further support the proposed reaction mechanism and its role in enhancing EHL's anti-fungal activity. This study offers novel insights into the high-value utilization of enzymatic hydrolysis lignin based on green chemistry principles.

Elongated galactan side chains mediate cellulose-pectin interactions in engineered Arabidopsis secondary cell walls.

The plant secondary cell wall is a thickened matrix of polysaccharides and lignin deposited at the cessation of growth in some cells. It forms the majority of carbon in lignocellulosic biomass, and it is an abundant and renewable source for forage, fiber, materials, fuels, and bioproducts. The complex structure and arrangement of the cell wall polymers mean that the carbon is difficult to access in an economical and sustainable way. One solution is to alter the cell wall polymer structure so that it is more suited to downstream processing. However, it remains difficult to predict what the effects of this engineering will be on the assembly, architecture, and properties of the cell wall. Here, we make use of Arabidopsis plants expressing a suite of genes to increase pectic galactan chain length in the secondary cell wall. Using multi-dimensional solid-state nuclear magnetic resonance, we show that increasing galactan chain length enhances pectin-cellulose spatial contacts and increases cellulose crystallinity. We also found that the increased galactan content leads to fewer spatial contacts of cellulose with xyloglucan and the backbone of pectin. Hence, we propose that the elongated galactan side chains compete with xyloglucan and the pectic backbone for cellulose interactions. Due to the galactan topology, this may result in comparatively weak interactions and disrupt the cell wall architecture. Therefore, introduction of this strategy into trees or other bioenergy crops would benefit from cell-specific expression strategies to avoid negative effects on plant growth.

Impacts of Structure-Directing Agents on the Synthesis of Cu3Mo2O9 for Flexible Lignin-Based Supercapacitor Electrodes

Due to demands for sustainability, the interest in energy storage devices constructed from green materials has increased immensely. These devices currently have yet to be satisfactory. Issues include high production costs and toxicity, limited dependability, and subpar electrochemical performance. In this research, low-cost, plant-based electroactive Cu3Mo2O9 materials were synthesized via co-precipitation followed by an annealing method using two different structure-directing agents, i.e., the commonly used surfactant cetyltrimethylammonium bromide (CTAB) and the biomolecule deoxyribonucleic acid (DNA) as a greener alternative, and these materials were studied for the first time. Further, the Cu3Mo2O9 nanoparticles developed using CTAB and DNA were integrated into the lignin matrix and studied as flexible electrodes for supercapacitor application. Here, the morphological advantages of the nanorods and nanosheets formed by varying the synthesis methods and their effects during supercapacitor studies were studied in detail. After 1200 cycles, the Al/lig-Cu3Mo2O9@DNA supercapacitor exhibited higher capacitive performance when compared to the Al/lig-Cu3Mo2O9@CTAB supercapacitor. The Al/Lig-Cu3Mo2O9@DNA supercapacitor had an initial specific capacitance of 404.64 mF g−1 with a ~70% retention, while the Al/Lig-Cu3Mo2O9@CTAB supercapacitor had an initial specific capacitance of 309.59 mF g−1 with a ~50% retention. This study offers a new approach to creating scalable, low-cost, green composite CuMoO4-based electrodes for flexible supercapacitors.

Antibacterial and high-performance bioplastics derived from biodegradable PBST and lignin

Herein, antibacterial bioplastic derived from lignin, poly(butylene succinate-co-butylene terephthalate) (PBST) was functionalized with the antibacterial lignin- g - (polyhexamethylene guanidine) (Lignin- g -PHMG). The Lignin- g -PHMG was synthesized by a facile grafting reaction. The epoxidized lignin provided sufficient reactive sites for the amine groups on PHMG. The structure of Lignin- g -PHMG was confirmed by Fourier-Transform Infrared Spectra (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). The antibacterial bioplastics were developed by introducing Lignin- g -PHMG into the matrix of PBST and lignin. The composite bioplastics exhibited good mechanical performance, with a tensile strength of 20.69 MPa and an elongation at break of 414.88%, respectively. Moreover, the composite films revealed good antioxidant properties, and a highly efficient scavenging rate of 98.21% was detected for DPPH free radicals. The bacterial inhibition by the bioplastic composite films demonstrated a synergistic antibacterial effect between lignin and Lignin- g -PHMG on E. coli and S. aureus . Furthermore, the inhibition zone test indicated that the bioplastic composite could provide a durable and nonleaching antibacterial performance. Therefore, this study contributes to the conversion of lignin into multifunctional composites with potential antioxidant and antimicrobial applications. • A novel lignin-based antibacterial agent was prepared by graft lignin and PHMG. • Lignin/PBST composites were prepared by melt blending with good overall performance. • Lignin enhanced PBST matrix and facilitate the high value-added application of lignin.

THERMAL BEHAVIOR OF COATED BIO-POLYMERS

Thermal behavior in plastic materials has a strong influence on their performance. In the current research, scientists are using different equipment that highlights the calorimetric behavior of parts by the identification and localization of transitions and exothermic/endothermic reactions that take place during material heating. The paper aims to characterize from a thermal point of view a lignin-based polymer (Arboblend V2 Nature) coated with three distinct micro-ceramic powders: two based on chrome oxide - Cr2O3, Cr2O3 -xSiO2 -yTiO2 (commercial name Amdry 6420 and Metco 136F) and one based on zirconium oxide - ZrO2 18TiO2 10Y2O3 (commercially known as Metco 143). The samples to be covered were obtained by injection in the mold and the coating technique used was a thermal – APS (Atmospheric Plasma Spray). After thermal analysis, all three coated samples reviled thermal stability up to 230°C, the degradation of the lignin matrix taking place around 345°C. Thus, based on this important data the recommendation to be used in practical applications can be made. So, the Arbobelnd V2 Nature bio-polymer coated with ceramic micro-particles works in normal working parameters for temperatures not exceeding 200°C. The paper also highlights in the beginning part the systemic analysis of the coating process in order to underline the factors that significantly influence the output parameters as: structure, morphology, mechanical, tribological, and thermal behavior.

Hydrogenation of CO in the Presence of Fe-Containing Materials Based on Carbon Supports

Hydrothermal carbonization of lignin was used to prepare a precursor of a carbon-containing support to obtain supported iron-containing catalysts for the hydrogenation of carbon monoxide. In the paper, the possibility of forming a carbon support prone to the deposition of metal ions was investigated. Deep structural transformations occurring in the polymer matrix of lignin were demonstrated by FTIR spectroscopy. The thermal stability of the support material was determined by thermal analysis in the region up to 400 °C. The formation of magnetite nanoparticles with a size of about 7‒8 nm at the stage of preliminary calcination of the metal-carbon system was shown by X-ray diffraction analysis (XRD). It was found that the resulting systems have high activity comparable to the activity of the system based on activated carbon: the conversion of carbon monoxide reached 98%, the yield of C5+ hydrocarbons reached 72 g/m3.

3D-Printed Polymer-Infiltrated Ceramic Network with Antibacterial Biobased Silver Nanoparticles.

This work aimed at the antimicrobial functionalization of 3D-printed polymer-infiltrated biomimetic ceramic networks (PICN). The antimicrobial properties of the polymer-ceramic composites were achieved by coating them with human- and environmentally safe silver nanoparticles trapped in a phenolated lignin matrix (Ag@PL NPs). Lignin was enzymatically phenolated and used as a biobased reducing agent to obtain stable Ag@PL NPs, which were then formulated in a silane (γ-MPS) solution and deposited to the PICN surface. The presence of the NPs and their proper attachment to the surface were analyzed with spectroscopic methods (FTIR and Raman) and X-ray photoelectron spectroscopy (XPS). Homogeneous distribution of 13.4 ± 3.2 nm NPs was observed in the transmission electron microscopy (TEM) images. The functionalized samples were tested against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria, validating their antimicrobial efficiency in 24 h. The bacterial reduction of S. aureus was 90% in comparison with the pristine surface of PICN. To confirm that the Ag-functionalized PICN scaffold is a safe material to be used in the biomedical field, its biocompatibility was demonstrated with human fibroblast (BJ-5ta) and keratinocyte (HaCaT) cells, which was higher than 80% in both cell lines.