Organosolv Lignin Barrier Paper Coatings from Waste Biomass Resources

Comprehensive characterization of lignins in the context of their valorization: A combination of NMR/2D-COS IR spectroscopy

The widespread development of lignin valorization is hindered by a number of challenges. In particular, efficient valorization necessitates comprehensive characterization of initial lignins. In this work, the structural features of lignins from birch wood (Bétula péndula), obtained by various methods of hard and mild fractionation of biomass: hydrolysis (Hyd-L), kraft (Kraft-L), soda (Soda-L), and soda-ethanol (SodaEt-L) processes, as well as organosolv processes with dioxane (MWL, DL) and dimethyl sulfoxide (DMSO-L) have been comprehensively studied. The main novelty of this study is the first-time application of Two-Dimensional Correlation Infrared Spectroscopy (2D-COS IR) for rapidly and comprehensively assessing structural transformations of lignins, in combination with 31P NMR. It has been established that changing delignification conditions primarily affects the processes of demethoxylation, dehydration and polymerization/condensation of lignin, and then the breaking of lignin-carbohydrates linkages. An approach to evaluating the potential of different types of lignin for valorization (valorization index), based on their structural characteristics, has been proposed. The applied approach allowed for the arrangement of the studied lignins in order of decreasing valorization index: DMSO-L, MWL, DL, SodaEt-L, Soda-L, Kraft-L.

Sustainable polylactic acid spunlace nonwoven fabrics with lignin/zinc oxide/water-based polyurethane composite coatings

In this paper, polylactic acid spunlace nonwoven fabrics were coated with lignin/zinc oxide/water-based polyurethane composite formulations, including five different ratios of lignin and zinc oxide, via a film applicator and thermally cured. The coated and thermally cured nonwoven fabrics were tested in terms of color values, tensile strength, abrasion resistance, ultraviolet protection, hydrophobicity, antibacterial activity, air, and vapor permeability properties. Characterization studies were conducted by FTIR, DSC, TGA, XRD, and SEM. The ultraviolet protection factor of 215.47 and a water contact angle of 90.27° were obtained with the fabric coated with WPU-1:5 formulation. Nonwoven fabric coated with the WPU-1:5 formulation showed evident antibacterial activity against S. aureus and E. coli bacteria as 89 % and 100 %, respectively. With the addition of lignin/ZnO into water-based polyurethane coating paste, PLA nonwoven fabric exhibited improved antibacterial activity, tensile strength, abrasion resistance, and ultraviolet light protection performance. However, composite coatings decreased air and vapor permeability and hydrophobicity of fabrics, but acceptable results were obtained. The results indicate that polylactic acid nonwoven fabrics, when treated with lignin/ZnO/WPU composite coatings, exhibit enhanced mechanical and functional properties, rendering them promising for applications in protective medical textiles.

Modified 1,4-butanediol organosolv pretreatment on hardwoodandsoftwood for efficient coproduction of fermentable sugars and lignin antioxidants

In this work, 1,4-butanediol (BDO) organosolv pretreatment was modified with different additives for efficient coproduction of fermentable sugars and lignin antioxidants from hardwood poplar and softwood masson pine. It was found additives more greatly improved pretreatment efficacy of softwood than hardwood. 3-hydroxy-2-naphthoic acid (HNA) addition introduced hydrophilic acid groups to lignin structure, while 2-naphthol-7-sulphonate (NS) addition promoted lignin removal, both improving cellulose accessibility for enzymatic hydrolysis. Consequently, BDO pretreatment with 90 mM acid and 2-naphthol-7-sulphonate addition achieved near complete cellulose hydrolysis (97.98%) and maximized sugar yield of 88.23% from masson pine at 2% cellulose and 20 FPU/g enzyme loading. More importantly, the recovered lignin possessed great antioxidant activity (RSI = 2.48), due to increased phenolic OH groups, reduced aliphatic OH groups and molecular weight. Results indicated the modified BDO pretreatment could significantly improve enzymatic saccharification of highly-recalcitrant softwood, while enabling coproduction of high-performance lignin antioxidants for full biomass utilization.

Modification of Paper Surface by All-Lignin Coating Formulations

All-lignin coating formulations were prepared while combining water-soluble cationic kraft lignin (quaternized LignoBoost®, CL) and anionic lignosulphonate (LS). The electrostatic attraction between positively charged CL and negatively charged LS led to the formation of insoluble self-organized macromolecule aggregates that align to films. The structures of the formed layers were evaluated by atomic force microscopy (AFM), firstly on glass lamina using dip-coating deposition and then on handsheets and industrial uncoated paper using roll-to-roll coating in a layer-by-layer mode. Coated samples were also characterized by optical microscopy, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (SEM/EDS), and contact angle measurements. It was suggested that the structure of all-lignin aggregates is the result of the interaction of amphiphilic water-soluble lignin molecules leading to their specifically ordered mutual arrangement depending on the order and the mode of their application on the surface. The all-lignin coating of cellulosic fiber imparts lower air permeability and lower free surface energy to paper, mainly due to a decrease in surface polarity, thus promoting the paper's hydrophobic properties. Moderate loading of lignin coating formulations (5-6 g m-2) did not affect the mechanical strength of the paper.

Invasive Alien Plant Species for Use in Paper and Packaging Materials

Invasive plant species can impede the establishment and growth of native plants and affect several ecosystem properties. These properties include soil cover, nutrient cycling, fire regimes, and hydrology. Controlling invasive plants is therefore a necessary, but usually expensive, step in restoring an ecosystem. The sustainability of materials with an emphasis on the use of local resources plays an important role in the circular economy. The use of alternative fibers from invasive plants promotes local production in smaller paper mills that offer the protection of local species and the reduction of waste and invasive plants. A synthesis of the literature is needed to understand the various impacts of invasive plants and their practical control in the context of papermaking applications and to identify associated knowledge gaps. To improve our understanding of the practical application of invasive species in the paper industry, we reviewed the existing literature on invasive plant species in the area of fiber production, printability, coating solution production, dyes, and extracts, and collected information on the major invasive plant species in Europe and the methods used for various applications.