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  • 1.
    Chinga Carrasco, Gary
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Pasquier, Eva
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Dalheim, Marianne Øksnes
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Wieser, Martin K.
    Elopak ASA, Norway.
    Development of a beverage carton closure cap based on 100% wood pulp fibres2024In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 445, article id 141339Article in journal (Refereed)
    Abstract [en]

    Single-use plastic products have been identified as an environmental challenge. When such products are not recycled, they may end up in nature and thus cause, e.g., marine littering. Thermoformed wood pulp fibre products are gaining more interest to replace fossil plastic products. However, beverage caps made of wood pulp fibres are challenging due to the hygroscopic nature of wood fibres, i.e., they absorb water, deform and loose functionality. Hence, the purpose of this study was to develop a fibre-based beverage cap that could replace plastic tethered cap systems. Both unbleached and bleached Kraft pulp and chemo-thermo-mechanical pulp (CTMP) fibres were tested in thermoforming trials, using tailor-made metal moulds. The results showed that Kraft pulp fibres formed denser structures, with more limited water absorption, compared to CTMP. The mechanical properties of thermoformed specimens were suitable for the application, i.e., the strength, modulus and elongation were between 32 and 36 MPa, 4–4.9 GPa and 1.6–1.9%, respectively, depending on the type of pulp fibre. Additionally, in order to secure that the caps were functional in relevant conditions in contact with liquids (water or milk), the caps were surface modified by silylation and esterification to increase the liquid barrier. The results indicate that surface esterification increased the contact angle to 95°. On the other hand, the surface-modified caps could not entirely limit the liquid absorption over longer periods of time (>∼1 h) when the caps were directly exposed to liquid. However, the liquid barrier was satisfactory when the products were exposed to increased relative humidity in refrigerated conditions (relative humidity >76% and temperature <7 °C). 

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  • 2.
    Dudek, M.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. NTNU Norwegian University of Science and Technology, Norway.
    Øye, G.
    NTNU Norwegian University of Science and Technology, Norway.
    Characterization and assessment of wax and wax inhibitors systems in microfluidic oil-in-water coalescence experiments2022In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 636, article id 128186Article in journal (Refereed)
    Abstract [en]

    During produced water treatment, one of the key underlying phenomena affecting separation performance is coalescence between oil droplets. These processes can be affected by several factors, including chemical composition of fluids, process conditions, droplet characteristics, but also presence of different production chemicals. In this paper, we study the effect of wax and wax inhibitors on the stability of oil droplets in brine with a microfluidic coalescence method. Three wax inhibitors with known chemistries were added to crude oil and solutions of macrocrystalline wax in dodecane. All the systems were characterized with regards to their physicochemical, rheological and interfacial properties, while the microfluidic coalescence measurements were performed below and above the wax appearance temperature. In most cases, higher concentration of the inhibitors lowered the coalescence frequency between the droplets, however the presence of wax often reduced the stabilizing effect of the additives. The most stable emulsions, often by 1–2 orders of magnitude, were obtained for the polycarboxylate wax inhibitor with the lowest molecular weight and exhibiting highest interfacial activity. Styrene block copolymer was also found to prevent coalescence, most likely by changing the mechanical properties of the interface, however this was strongly affected by the concentration of wax in the solution. Higher temperature mostly affected the inhibitor-paraffin or inhibitor-solvent interactions, which resulted in increase or reduction of emulsion stability, depending on the inhibitor. Crude oil systems, more stable than model solutions to begin with, were found to be only slightly affected by the presence of additives. This was mostly attributed to the abundance presence of crude oil indigenous surface-active components. Still, in all cases when an additive was present, the stability of droplets increased. Overall, this study underlines the importance of non-separation related production chemicals within the wider frame of separation processes in upstream petroleum processing. © 2021 The Author(s)

  • 3.
    Heen Blindheim, Fredrik
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    The Effect of Sample Preparation Techniques on Lignin Fourier Transform Infrared Spectroscopy2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 13, article id 2901Article in journal (Refereed)
    Abstract [en]

    The characterization and quantification of functional groups in technical lignins are among the chief obstacles of the utilization of this highly abundant biopolymer. Although several techniques were developed for this purpose, there is still a need for quick, cost-efficient, and reliable quantification methods for lignin. In this paper, three sampling techniques for fourier transform infrared (FTIR) spectroscopy were assessed both qualitatively and quantitatively, delineating how these affected the resultant spectra. The attenuated total reflectance (ATR) of neat powders and DMSO-d6 solutions, as well as transmission FTIR using the KBr pelleting method (0.5 wt%), were investigated and compared for eight lignin samples. The ATR of neat lignins provided a quick and easy method, but the signal-to-noise ratios in the afforded spectra were limited. The ATR of the DMSO-d6 solutions was highly concentration dependent, but at a 30 wt%, acceptable signal-to-noise ratios were obtained, allowing for the lignins to be studied in the dissolved state. The KBr pelleting method gave a significant improvement in the smoothness and resolution of the resultant spectra compared to the ATR techniques. Subsequently, the content of phenolic OH groups was calculated from each FTIR mode, and the best correlation was seen between the transmission mode using KBr pellets and the ATR of the neat samples (R2 = 0.9995). Using the titration measurements, the total OH and the phenolic OH group content of the lignin samples were determined as well. These results were then compared to the FTIR results, which revealed an under-estimation of the phenolic OH groups from the non-aqueous potentiometric titration, which was likely due to the differences in the pKa between the lignin and the calibration standard 4-hydroxybenzoic acid. Further, a clear correlation was found between the lower (Formula presented.) and the increased phenolic OH group content via SEC analyses. The work outlined in this paper give complementary views on the characterization and quantification of technical lignin samples via FTIR. © 2023 by the authors.

  • 4.
    Heen Blindheim, Fredrik
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Syverud, Kristin
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Lignin-Based Wax Inhibitors2024In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 38, no 4, p. 2898-2909Article in journal (Refereed)
    Abstract [en]

    This article tested a novel concept for synthesizing green wax inhibitors. Four technical lignins were reacted with stearoyl chloride to produce esterified C18 esterified lignin. The effect of the reaction on the lignin molecular weight, characteristic FTIR spectra, and thermal degradation was surveyed. In addition, wax inhibition testing was performed by rheology on model waxy oils. The grafting reactions increased the mass-average molecular weight of the lignin and in some cases also the polydispersity index. FTIR analysis confirmed the success of esterification reactions as the O-H stretching band decreased, whereas the C-H and C═O stretching bands significantly increased. The thermal degradation was further found to occur at temperatures above 170 °C, indicating that the lignin wax inhibitors were thermally stable enough for crude oil production. The effect on waxy gelation was varied, showing that the low molecular weight waxes benefited more than the high molecular ones. A gelation point reduction of up to 6 °C was found after lignin addition. After the wax type, wax concentration, lignin concentration, and lignin type were varied, it was found that C18 esterified Kraft lignin exhibited the most beneficial effect. The results from viscometry agreed with the observations from the rheometric gelation point. Cross-polarized microscopy was used to map the effect on the wax crystal morphology. A difference was found only in the case of one esterified Kraft lignin, which yielded smaller and more finely dispersed wax crystals. In conclusion, a new wax inhibitor was synthesized by reacting technical lignin with stearoyl chloride. This lignin showed wax inhibitor activity in some of the tested cases. At this point, the length of the pendant alkyl chains (C18) is likely a limiting factor. However, this study attributes the potential for a new concept to synthesize green wax inhibitors. 

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  • 5.
    Opedal, Mihaela Tanase
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Organosolv Lignin as a Green Sizing Agent for Thermoformed Pulp Products2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 50, p. 46583-46593Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the use of organosolv lignin as a sizing agent for thermoformed pulp products as a sustainable material with improved water resistance. For this purpose, an in-house-produced organosolv lignin from softwood (Norway Spruce) was mixed with bleached and unbleached chemi-thermomechanical pulp fibers. In addition, the isolated organosolv lignin was characterized by ATR-FTIR spectroscopy, size-exclusion chromatography, and thermogravimetric analysis. The analysis showed that organosolv lignin was of a high purity and practically ash-free, exhibiting low molecular weight, a glass transition temperature below the thermoforming temperature, and a high content of phenolic OH groups. The mechanical properties and water resistance of the organosolv lignin-sized thermoformed pulp materials were measured. A small decrease in strength and an increase in stiffness and density were observed for the lignin-sized thermoformed materials compared to the reference, that is, unsized materials. The addition of organosolv lignin decreased the wettability and swelling of the thermoformed product. These results are due to the distribution of organosolv lignin on the surface, filling in the pores and cavities, and providing a tighter fit within the thermoformed materials. In conclusion, the results from our study encourage the use of organosolv lignin as a sizing additive to thermoformed products, which can improve the water resistance to use it in sustainable packaging applications.

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  • 6.
    Pasquier, Eva
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Skunde, Robert
    TU-Berlin, Germany.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. TU-Berlin, Germany.
    Influence of temperature and pressure during thermoforming of softwood pulp2023In: Journal of Bioresources and Bioproducts, ISSN 2369-9698, Vol. 8, no 4, p. 408-420Article in journal (Refereed)
    Abstract [en]

    In this study, the influence of thermoforming conditions on the resulting material properties was investigated, which aimed at developing advanced wood-fiber-based materials for the replacement of fossil plastics. Two bleached softwood pulps were studied, i.e., northern bleached softwood Kraft pulp (NBSK) and chemi-thermomechanical softwood pulp (CTMP). The thermoforming conditions were varied between 2–100 MPa and 150–200 °C, while pressing sheets of 500 g/m² for 10 min to represent thin-walled packaging more closely. As our results showed, the temperature had a more pronounced effect on the CTMP substrates than on the Kraft pulp. This was explained by the greater abundance of lignin and hemicelluloses, while fibrillar dimensions and the fines content may play a role in addition. Moreover, the CTMP exhibited an optimum in terms of tensile strength at intermediate thermoforming pressure. This effect was attributed to two counteracting effects: 1) Improved fiber adhesion due to enhanced densification, and 2) embrittlement caused by the loss of extensibility. High temperatures likely softened the lignin, enabling fiber collapse and a tighter packing. For the Kraft substrates, the tensile strength increased linearly with density. Both pulps showed reduced wetting at elevated thermoforming temperature and pressure, which was attributed to hornification and densification effects. Here, the effect of temperature was again more pronounced for CTMP than for the Kraft fibers. It was concluded that the thermoforming temperature and pressure strongly affected the properties of the final material. The chemical composition of the pulps will distinctly affect their response to thermoforming, which could be useful for tailoring cellulose-based replacements for packaging products. 

  • 7.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Chinga Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Opedal, Mihaela Tanase
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Sustainable Materials from Organosolv Fibers and Lignin, Kraft Fibers, and Their Blends2024In: Polymers, E-ISSN 2073-4360, Vol. 16, no 3, article id 377Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate new materials from organosolv fibers, organosolv lignin, kraft fibers, and their blends. The organosolv fibers showed reprecipitated lignin on the surface, a comparably low fiber length of 0.565 mm on average, and a high fines content of 82.3%. Handsheets were formed and thermopressed at 175 °C and 50 MPa, yielding dense materials (1050–1100 kg/m3) with properties different to that of regular paper products. The thermopressing of organosolv fibers alone produced materials with similar or better tensile strength (σb = 18.6 MPa) and stiffness (E* = 2.8 GPa) to the softwood Kraft reference pulp (σb = 14.8 MPa, E* = 1.8 GPa). The surface morphology was also smoother with fewer cavities. As a result, the thermopressed organosolv fibers exhibited higher hydrophobicity (contact angle > 95°) and had the lowest overall water uptake. Combinations of Kraft fibers with organosolv fibers or organosolv lignin showed reduced wetting and a higher density than the Kraft fibers alone. Furthermore, the addition of organosolv lignin to Kraft fibers greatly improved tensile stiffness and strength (σb = 23.8 MPa, E* = 10.5 GPa), likely due to the lignin acting as a binder to the fiber network. In conclusion, new thermopressed materials were developed and tested, which show promising potential for sustainable fiber materials with improved water resistance.

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  • 8.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Handiso, Berhane
    NTNU, Norway.
    Øksnes Dalheim, Marianne
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Solberg, Amalie
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Simon, Sébastien
    NTNU, Norway.
    Syverud, Kristin
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. NTNU, Norway.
    Interfacial Adsorption of Oil-Soluble Kraft Lignin and Stabilization of Water-in-Oil Emulsions2024In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 40, no 10, p. 5409-5419Article in journal (Refereed)
    Abstract [en]

    In this paper, the potential of esterified Kraft lignin as a novel oil-soluble surfactant was examined. The lignin was chemically modified by esterification with lauric or stearic acid, making it soluble in solvents such as toluene or n-decane. Adsorption at the oil-water interface was then studied by the Du Noüy ring-method. The oil-soluble lignin behaved similar to water-soluble lignin surfactants, both the qualitative and quantitative progression of interfacial tension. Modeling revealed a surface excess of 7.5-9.0 × 10-7 mol/m2, area per molecule of 185-222 Å2, and a diffusion coefficient within the range 10-10 to 10-14 m2/s; all of which are in line with existing literature on water-soluble lignosulfonates. The data further suggested that the pendant alkyl chains were extended well into the paraffinic solvent. At last, bottle tests showed that the oil-soluble lignin was able to stabilize oil-in-water emulsions. The emulsion stability was affected by the concentration of lignin or NaCl as well as the oil phase composition. Aromatic oils exhibited lower emulsion stability in comparison to the aliphatic oil. In conclusion, a new type of surfactant was synthesized and studied, which may contribute to developing green surfactants and novel approaches to valorize technical lignin.

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  • 9.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Heen Blindheim, Fredrik
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Chinga Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Functional surfaces, films, and coatings with lignin - a critical review2023In: RSC Advances, E-ISSN 2046-2069, Vol. 13, no 18, p. 12529-12553Article in journal (Refereed)
    Abstract [en]

    Lignin is the most abundant polyaromatic biopolymer. Due to its rich and versatile chemistry, many applications have been proposed, which include the formulation of functional coatings and films. In addition to replacing fossil-based polymers, the lignin biopolymer can be part of new material solutions. Functionalities may be added, such as UV-blocking, oxygen scavenging, antimicrobial, and barrier properties, which draw on lignin's intrinsic and unique features. As a result, various applications have been proposed, including polymer coatings, adsorbents, paper-sizing additives, wood veneers, food packaging, biomaterials, fertilizers, corrosion inhibitors, and antifouling membranes. Today, technical lignin is produced in large volumes in the pulp and paper industry, whereas even more diverse products are prospected to be available from future biorefineries. Developing new applications for lignin is hence paramount - both from a technological and economic point of view. This review article is therefore summarizing and discussing the current research-state of functional surfaces, films, and coatings with lignin, where emphasis is put on the formulation and application of such solutions. 

  • 10.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Opedal, Mihaela Tanase
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Green materials from added-lignin thermoformed pulps2022In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 185, article id 115102Article in journal (Refereed)
    Abstract [en]

    In this article, added-lignin thermoformed pulps (ALTP) were explored as a new alternative for green materials. Technical lignin was added to mechanical pulp and subsequently thermoformed, yielding a biobased material with lignin contents above natural levels. This material was tested for its mechanical properties, water-uptake, and density. In addition, FTIR and TGA-DSC were used to characterize the lignin samples, i.e., Soda, Kraft, and hydrolysis lignin, as well as lignosulfonates. The material properties were significantly changed at 20 – 40 wt% added-lignin per dry fiber. Lignin addition increased density and reduced water-uptake and wettability. The effect on mechanical properties could vary, however, pure lignin had a more beneficial effect than hydrolysis lignin containing residual cellulose. Higher stiffness was observed for the pure lignin samples at constant or decreasing tensile strength. In conclusion, ALTP is a promising material for developing new pulp products and plastics-replacements, where the ratio and type of added-lignin may be used to fine-tune the desired characteristics. © 2022 The Authors

  • 11.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Opedal, Mihaela Tanase
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Syverud, Kristin
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ultraviolet Spectrophotometry of Lignin Revisited: Exploring Solvents with Low Harmfulness, Lignin Purity, Hansen Solubility Parameter, and Determination of Phenolic Hydroxyl Groups2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 50, p. 46371-46383Article in journal (Refereed)
    Abstract [en]

    In this article, we explored solvents with lower harmfulness than established systems for UV spectrophotometry of lignin. By measuring the absorptivity in DMSO solvent at 280 nm, the purity of the lignin samples was addressed and compared with Klason and acid-soluble lignin. The general trend was an increasing absorptivity with increasing lignin purity; however, considerable scattering was observed around the sample mean. The Hansen solubility parameter (HSP) of four technical lignins was furthermore determined. The model was in line with the UV measurements, as solvents closer in HSP correlated with a higher absorptivity. Ethylene glycol was identified as a good solvent for lignin with low UV-cutoff. In addition, mixtures of propylene carbonate, water, and ethanol showed good suitability and a low cutoff of 215 nm. While DMSO itself was poorly suited for recording alkali spectra, blending DMSO with water showed great potential. Comparing three methods for determining phenolic hydroxyl units by UV spectrophotometry showed some discrepancies between different procedures and solvents. It appeared that the calibrations established with lignin model compounds may not be fully representative of the lignin macromolecule. More importantly, the ionization difference spectra were highly affected by the solvent of choice, even when using what are considered "good"solvents. At last, a statistical comparison was made to identify the most suitable solvent and method, and the solvent systems were critically discussed. We thus conclude that several solvents were identified, which are less harmful than established systems, and that the solubility of lignin in these is a crucial point to address when conducting UV spectrophotometry. 

  • 12.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Syverud, Kristin
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Opedal, Mihaela Tanase
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Purification of soda lignin2024In: Sustainable Chemistry for the Environment, ISSN 2949-8392, Vol. 6, article id 100102Article in journal (Refereed)
    Abstract [en]

    Purity of technical lignin is one of the main obstacles in the utilization of lignin to value-added chemicals, products, and materials. The objective of this study was to investigate and compare single and two stage purification methods for obtaining soda lignin with high purity. Extensive washing and extraction with water was found effective, increasing the abundance of acid insoluble lignin while reducing its ash content. Extraction with organic solvents was conducted with 2-propanol or blends of n-heptane/1-butanol or cyclohexane/acetone. These solvents were shown to have little effect on the total lignin content, as determined by wet-chemical methods. Two-stage treatments (washing with water followed by solvent extraction) were hence not better than single stage water extraction in terms of the lignin purity. Still, selective removal of low molecular weight components after solvent extraction was noted, reducing the overall polydispersity of the lignin. Evaporation at 40 °C also showed little effect, whereas calcination at 150 °C significantly increased the molecular weight of the soda lignin. The latter effect was explained by thermally induced cross-linking. In addition, the UV absorbance of the calcinated lignin increased, which is likely related to changes in the aromatic structure. Such effect also entailed that UV/vis spectrophotometry was found less reliable in determining the total lignin content. At last, a mathematical model was adapted to predict the total lignin content from FTIR spectrometry. In conclusion, the tested procedures can be used to purify soda lignin and adjust its molecular weight.

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  • 13.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Toven, Kai
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Alternative wood treatment with blends of linseed oil, alcohols and pyrolysis oil2022In: Journal of Bioresources and Bioproducts, ISSN 2369-9698, Vol. 7, no 4, p. 278-287Article in journal (Refereed)
    Abstract [en]

    Linseed oil is a common wood treatment agent, which is often blended with naphthenic oil during its application. In this study, we developed new types of linseed oil blends, where the naphthenic oil was substituted with alcohols and pyrolysis oil. As miscibility tests revealed, linseed oil can be blended indefinitely with primary alcohols containing three carbon atoms or more. In addition, kinetic stability of three-component-mixtures was found, which comprised linseed oil, alcohol and pyrolysis oil. The developed blends were further tested for their viscosity and rate of solvent evaporation. At last, trial impregnations of wood were done to test this new treatment agent. The uptake of treatment oil and the effect on water repellency varied, and substituting white spirit with propanol and pyrolysis oil showed potential. The latter were miscible with 50% (wt) linseed oil at concentrations of 37.5% 1- or 2-propanol and 12.5% pyrolysis oil. Compared with the reference case, treatment with this agent markedly decreased the water-uptake of the wood. Our study hence attributes great potential to the newly developed linseed oil blends, which may introduce additional product characteristics and generate value to byproducts via pyrolysis. © 2022 The Author(s)

  • 14.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. NTNU Norwegian University of Science and Technology, Norway.
    Øye, Gisle
    NTNU Norwegian University of Science and Technology, Norway.
    Effect of Low-Molecular-Weight Alcohols on Emulsion Stabilization with Lignosulfonates2020In: ACS Omega, E-ISSN 2470-1343, Vol. 5, no 46, p. 30168-30175Article in journal (Refereed)
    Abstract [en]

    Lignosulfonates are biobased surfactants and specialty chemicals, which are described as water-soluble polyelectrolyte macromolecules that are generated during the sulfite pulping of lignocellulose biomass. Due to their amphiphilic nature, lignosulfonates have made their way into various applications, such as plasticizers, dispersants, and suspension or emulsion stabilizer. The stabilization efficiency for oil-in-water emulsions is affected, among other aspects, by the presence of alcohols. Low-molecular-weight alcohols can improve the performance of lignosulfonates; however, the effects of such additive have not yet been fully explored. In this article, we hence studied emulsion stability in dependence of alcohol concentration and other parameters, such as salinity. One or two regions of improved stability were found, which occurred at approximately 0.001-0.01 M alcohol in water, and in some cases additionally at 1-3 M. The four lignosulfonate samples responded distinctly to the alcohol additives. Little difference was found for varying lignosulfonate concentration or the alcohol type, that is, methanol, ethanol, or 2-propanol. Adding ethanol at high salinity (720 mM NaCl) showed a destabilizing effect. A decrease in interfacial tension was noted when adding 1 M ethanol or more, but the surface pressure of lignosulfonates decreased progressively at 0.3 M ethanol and above. These effects are counteracting, which could explain why increasing alcohol concentration would either enhance or impair stability. Overall, emulsion stability was affected by concentration effects and not cosurfactant action of the alcohols. Composition changes can influence the dielectric properties of the bulk solvent, further affecting the anionic functional groups, which was evidenced by alcohol addition affecting the lignosulfonates with lower hydrophobicity more strongly and by ethanol exhibiting the destabilizing effect at high salinity. In conclusion, adding low-molecular-weight alcohols may hence influence the behavior of lignosulfonates and render them more accessible for interactions with hydrophobic interfaces. ©

  • 15.
    Simon, Sebastien
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Saadat, Marzieh
    NTNU Norwegian University of Science and Technology, Norway.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. NTNU Norwegian University of Science and Technology, Norway.
    Dudek, Marcin
    NTNU Norwegian University of Science and Technology, Norway.
    Ellis, Ross
    Borregaard AS, Norway.
    Øye, Gisle
    NTNU Norwegian University of Science and Technology, Norway.
    Lignosulfonates in Crude Oil Processing: Interactions with Asphaltenes at the Oil/Water Interface and Screening of Potential Applications2020In: ACS Omega, E-ISSN 2470-1343, Vol. 5, no 46, p. 30189-30200Article in journal (Refereed)
    Abstract [en]

    The goal of this article is to test the potential application of lignosulfonates (LSs) in crude oil production and processing. Three LS samples of varying hydrophobicity and average molecular weight were considered. First, the interfacial tension between brine and xylene and interfacial dilational rheology properties of LS samples were measured. It was found that the most surface-active LS sample has the lowest molecular weight in agreement with the results from the literature. In the presence of asphaltenes, all three LS samples were able to compete with asphaltenes, the most polar crude oil component, at the interface and form mixed LS-asphaltene interfaces. However, only the most surface-active LS sample among the three tested could fully desorb asphaltenes at the highest tested LS concentration (500 ppm). Second, three possible applications were screened. LSs were tested to prevent the formation of w/o crude oil emulsions or to break these. However, the opposite effect was observed, that is, stabilization of water-in-crude oil emulsions. The potential application of LS in produced water (PW) clarification was furthermore considered. The kinetics of PW clarification was found unaffected by the presence of LS, even at very high concentrations (1000 ppm). Finally, the potential of LS for enhanced oil recovery was assessed. The LS flood changed the surface wettability toward water wetness for one of the samples, yet LS injection did not recover additional oil beyond brine recovery. It was concluded that LS has interesting properties, such as the potential to compete with crude oil indigenous components at the oil/water interface. The stabilization action of LS was dominant over any destabilization effect, which led to the conclusion that LSs are more efficient for stabilizing emulsions rather than destabilizing.

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