The article introduces a detailed model for carbohydrate chemistry in kraft pulping. This article is continuation to the modeling work carried out for hot water extraction and chemical pulp bleaching. The model includes galactoglucomannan, xylan, and cellulose acid–base equilibria, in addition to peeling, stopping, and alkaline hydrolysis reactions of the same carbohydrates, as well as hexenuronic acid formation and degradation reactions. The Arrhenius parameters were applied from the literature or regressed against experimental data in the present study. The model is very successful in predicting the experimental data of carbohydrate reactions during kraft pulping. Many features of the pulping‐related model can be applied to specific fractionation chemistry considerations. The detailed knowledge on carbohydrates composition at any stage of pulping gives possibility for further development of biorefinery cases based on kraft pulping, such as biofuel and chemicals production.

The purpose of this study was to elucidate the structures and functional properties of tannin- and lignin-derived nano- and microparticles and the coatings prepared from them. Nanoparticles prepared from technical lignins and water-insoluble tannin obtained from softwood bark showed large differences in the suspension testing of antibacterial efficacy against methicillin-resistant Staphylococcus aureus (MRSA) bacteria. A common factor among the most effective lignin nanoparticles was a relatively low molar mass of the lignin, but that alone did not guarantee high efficacy. Tannin nanoparticles showed good antibacterial activity both in suspension testing and as coatings applied onto cellulose. The nanoparticles of nitrogen-modified tannin and the small microparticles of nitrogen-modified kraft lignin exhibited promising flame-retardant parameters when applied as coatings on cellulose. These results illustrate the potential of nano- and microsized particles of unmodified and chemically modified polyphenols to provide functional coatings to cellulosic substrates for environments and applications with high hygiene and fire safety requirements.

Bio-based products can help us to reach sustainability goals and reduce our dependency on fossil-based raw materials. Lignin is an abundantly available bio-based material. Recently, a concept of an alkali–O₂ oxidation (LigniOx) process for feasibly producing lignin dispersants at a kraft pulp mill has been introduced. The oxidation process uses O₂ gas to increase the anionic charge of lignin and the final oxidized lignin can serve as a concrete plasticizer or versatile dispersant. Life cycle assessment (LCA) is a tool widely used to holistically evaluate the environmental benefits of various products. The goal of this study was to evaluate the versatility of the novel lignin dispersants produced from kraft lignin and to compare the environmental performance with the synthetic products using an attributional cradle-to-gate LCA. Results showed that LigniOx impacts were lower than synthetic equivalents for both the end uses—superplasticizer and dispersants—in most of the impact categories. The only negative impact was on eutrophication that arises from fly ash purging at the kraft pulping process even without the integrated LigniOx production. In addition, the production of LigniOx lignin appeared to be more attractive than conventionally recovered kraft-lignin. LigniOx contributed minimally to the total impacts with the majority of impacts arising from the kraft pulping process.

The degradation kinetics of a non-phenolic lignin model compound with α-carbonyl functionality (adlerone) has been studied by varying temperature and concentrations of sodium hydroxide, sodium hydrogen sulfide, and sodium sulfite. The kinetics of adlerone degradation and formation of its reaction products were monitored by UV-Vis spectroscopy and their structures were analyzed by GC/MS. The two step degradation of adlerone was studied in two separate experimental setups. In the first alkali catalyzed step, adlerone is converted to a β-elimination product that reacts further in the second step with hydrogen sulfide or sulfite ion. The Arrhenius kinetic parameters were derived by the KinFit software. The activation energy for the 1^st step was 69.1 kJ mol^-1, and for the 2^nd step with sulfide 42.4 kJ mol^-1 and with sulfite ion 35.8 kJ mol^-1. The reaction mechanisms presented are in line with those published earlier: β-ether bonds of structures having α-carbonyl functionality do not cleave under soda pulping conditions, whereas in kraft and sulfite pulping the cleavage of β-ether bonds proceeds via nucleophile attack and addition. The combination of hydroxyl and sulfite ions gives the fastest cleavage of β-ether bonds in non-phenolic lignin structures with the α-carbonyl functionality.