The characteristics of two novel types of technical lignin, namely Ecohelix (EH) and CleanFlow black lignin (CFBL), isolated from two different pulping process side streams, were analyzed. EH and CFBL were analyzed in terms of general composition, chemical functionalities, molar mass distribution, and thermal stability. For comparison, two relevant types of commercially available lignosulfonate and kraft lignin were used. The results showed that EH contains a large amount of sulfonated lignin, together with carbohydrates and ash. As such, it can be considered a lignin-carbohydrate hybrid molecule. CFBL was found to contain 91.5% Klason lignin and the lowest amount of carbohydrates (0.3%). EH showed the highest content of aliphatic OH groups (5.44 mmol/g) and CFBL a high content of phenols (4.73 mmol/g). EH had a molecular weight of 31.4 kDa and a sufficient thermal stability. CFBL had the lowest molecular weight (M-w = 2.0 kDa) and thermal stability of all kraft lignins analyzed in this study. These properties highlighted that EH is a suitable building block for material development and that CFBL is a promising material for the production of biofuel and biochemicals.

Several different methods for the extraction, separation, and purification of wood constituents were combined in this work as a unified process with the purpose of achieving a high overall efficiency of material extraction and utilization. This study aimed to present a laboratory-scale demonstrator biorefinery that illustrated how the different wood constituents could be separated from the wood matrix for later use in the production of new bio-based materials and chemicals by combining several approaches. This study builds on several publications and ongoing activities within the Wallenberg Wood Science Center (WWSC) in Sweden on the theme "From wood to material components." Combining the approaches developed in these WWSC projects - including mild steam explosion, membrane and chromatographic separation, enzymatic treatment and leaching, ionic liquid extraction, and fractionation together with Kraft pulping - formed an outline for a complete materials-biorefinery. The process steps involved were tested as integral steps in a linked process. The scale of operations ranged from the kilogram-scale to the gram-scale. The feasibility and efficiency of these process steps in a biorefinery system were assessed, based on the data, beginning with whole wood.

In this study, new wood-inspired films were developed from microfibrillated cellulose and galactoglucomannan-lignin networks isolated from chemothermomechanical pulping side streams and cross-linked using laccase enzymes. To the best of our knowledge, this is the first time that cross-linked galactoglucomannan-lignin networks have been used for the potential development of composite films inspired by woody-cell wall formation. Their capability as polymeric matrices was assessed based on thermal, structural, mechanical and oxygen permeability analyses. The addition of different amounts of microfibrillated cellulose as a reinforcing agent and glycerol as a plasticizer on the film performances was evaluated. In general, an increase in microfibrillated cellulose resulted in a film with better thermal, mechanical and oxygen barrier performance. However, the presence of glycerol decreased the thermal stability, stiffness and oxygen barrier properties of the films but improved their elongation. Therefore, depending on the application, the film properties can be tailored by adjusting the amounts of reinforcing agent and plasticizer in the film formulation.

In this study we were mirroring suggested in vivo phenomena of lignin-hemicellulose complex formation in vitro, by cross-linking Norway spruce (Picea abies) galactoglucomannans, xylans and lignin moieties to high molecular weight complexes by laccase treatment. We were able to observe the oxidation and cross-linking of non-condensed guaiacyl-type phenolic moieties attached to both of the hemicelluloses by P-31 NMR and size-exclusion chromatography. We suggest that hemicelluloses-lignin complexes form covalently linked structural units during the early stages of lignification via radical enzymatic cross-linking catalyzed by laccase. This work shows that the hemicellulose molecules in wood are covalently linked to two or more lignin units thereby making them suited for forming network structures.

Wood, the most abundant ligno-cellulosic raw material available, is a key potential feedstock for production of more sustainable alternatives to fossil-based materials. However advances within the fields of extraction and treatment processes within what is often referred to as the biorefinery concept is essential to allow for such transition. In this study, several different methods for the extraction and separation of wood constituents have been combined in a single process with the purpose of achieving a high overall efficiency of material extraction and utilisation. The work builds on several activities within the Wallenberg Wood Science Center (WWSC). The aim is to present a laboratory-scale demonstrator that illustrates how the different constituents can be separated from the wood matrix for later use in the production of bio-based materials and chemicals. The process steps involved have been tested as integral steps in a linked process for a scale of operations that range from the kilogram-scale down to the gram-scale. Industrially chipped softwood, containing mainly spruce with some pine, was used as raw material. 

Hemicelluloses with high molecular mass are needed for the manufacture of value added products such as food packaging barrier films. In this work such molecules were recovered from chemithermomechanical pulp (CTMP) process water using an innovative three-stage process comprising membrane separation and enzymatic treatment with laccase. Microfiltration followed by ultrafiltration was found to be a suitable combination in the first stage, providing a concentrated and purified hemicellulose fraction suitable for enzymatic treatment. In both membrane processes a high average flux (260 and 115 l/m(2) h) and a low fouling tendency were observed. A marked increase in the average molecular mass of hemicelluloses with bound lignin moieties was achieved by laccase treatment in the second stage. The enzymatically crosslinked hemicelluloses were finally recovered in the third stage using ultrafiltration. In the final high molecular mass solution the hemicellulose concentration was 54 g/l, the contribution of hemicelluloses to the total solids content 43%, and the viscosity of the solution 27 mPa s. The results demonstrate that a hemicellulose fraction of high quality can be produced from CTMP process water, and that this could constitute a suitable feedstock for the production of, for example, barrier films for renewable packaging.

Hemicelluloses are one of the main constituents of plant cell walls and thereby one of the most abundant biopolymers on earth. They can be obtained as by-products from different wood based processes, most importantly from the mechanical pulping. Hemicelluloses have interesting properties in e.g. barrier film applications. However, their relatively low molecular weight after isolation and co-extraction with lignin has limited their use. In this work, we present a novel technique for increasing the molecular weight of different wood hemicelluloses from mechanical pulping process waters as well as from pre-hydrolysis extracts. This is achieved by enzyme-catalyzed cross-linking of aromatic moieties bound to the hemicelluloses. The cross-linking treatment resulted in significantly improved mechanical properties in barrier films made with spruce galactoglucomannan. To our knowledge, this is the first time that wood hemicelluloses have been cross-linked by utilizing the bound aromatic moieties and creates new possibilities for utilizing this raw material source.