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Chinga Carrasco, G., Ruwoldt, J., Pasquier, E., Dalheim, M. Ø. & Wieser, M. K. (2024). Development of a beverage carton closure cap based on 100% wood pulp fibres. Journal of Cleaner Production, 445, Article ID 141339.
Open this publication in new window or tab >>Development of a beverage carton closure cap based on 100% wood pulp fibres
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2024 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 445, article id 141339Article in journal (Refereed) Published
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). 

Place, publisher, year, edition, pages
Elsevier Ltd, 2024
Keywords
Beverages; Caps; Esters; Fibers; Hot Forming; Products; Pulps; Water Absorption; Beverages; Fibers; Thermoforming; Water absorption; Beverage cartons; Condition; Exposed to; Liquid barriers; Pulp fibers; Surface-modification; Surface-modified; Thermo mechanical pulps; Wood pulp fibers; Woodfiber; Esters
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-72941 (URN)10.1016/j.jclepro.2024.141339 (DOI)2-s2.0-85185844082 (Scopus ID)
Note

The authors thank Elopak AS and the Research Council of Norway for funding (NEPP project, Grant: 309441). 

Available from: 2024-04-25 Created: 2024-04-25 Last updated: 2024-04-25Bibliographically approved
Ruwoldt, J., Handiso, B., Øksnes Dalheim, M., Solberg, A., Simon, S. & Syverud, K. (2024). Interfacial Adsorption of Oil-Soluble Kraft Lignin and Stabilization of Water-in-Oil Emulsions. Langmuir, 40(10), 5409-5419
Open this publication in new window or tab >>Interfacial Adsorption of Oil-Soluble Kraft Lignin and Stabilization of Water-in-Oil Emulsions
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2024 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 40, no 10, p. 5409-5419Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
American Chemical Society, 2024
Keywords
Alkanes; Bottles; Emulsions; Esters; Glycerol; Bottles; Emulsions; Esters; Glycerol; Lignin; Organic solvents; Ostwald ripening; Paraffins; Phase interfaces; Sodium chloride; Surface active agents; decane; lignin; oil; solvent; stearic acid; surfactant; toluene; water; water oil cream; American Chemical Society; Chemically modified; Emulsion stability; Interfacial adsorption; Kraft lignin; N-decane; Oil soluble; Soluble surfactants; Water-in-oil emulsions; Watersoluble; adsorption; article; controlled study; diffusion coefficient; emulsion; esterification; nonhuman; pharmaceutics; surface tension; Emulsification
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-72937 (URN)10.1021/acs.langmuir.3c03950 (DOI)2-s2.0-85186374367 (Scopus ID)
Note

This work was carried out as a part of project “LignoWax─Green Wax Inhibitors and Production Chemicals based on Lignin”, grant number 326876. The authors gratefully acknowledge the financial support from the Norwegian Research Council, Equinor ASA, and ChampionX Norge AS. The authors would further like to thank Fredrik Heen Blindheim for help with the FTIR analysis.

Available from: 2024-04-25 Created: 2024-04-25 Last updated: 2024-04-25Bibliographically approved
Heen Blindheim, F., Syverud, K. & Ruwoldt, J. (2024). Lignin-Based Wax Inhibitors. Energy & Fuels, 38(4), 2898-2909
Open this publication in new window or tab >>Lignin-Based Wax Inhibitors
2024 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 38, no 4, p. 2898-2909Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
American Chemical Society, 2024
Keywords
Chlorine Compounds; Copolymerization; Esterification; Esters; Gelation; Molecular Weight; Chlorine compounds; Esterification; Esters; Fourier transform infrared spectroscopy; Gelation; Grafting (chemical); Molecular weight; American Chemical Society; FTIR; Gelation point; Kraft lignin; Lignin molecular weights; Novel concept; Spectra’s; Thermal degradation’; Wax crystals; Wax inhibitors; Lignin
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-72943 (URN)10.1021/acs.energyfuels.3c04768 (DOI)2-s2.0-85184795889 (Scopus ID)
Note

This work was carried out as a part of project “LignoWax – Green Wax Inhibitors and Production Chemicals based on Lignin”, grant number 326876. The authors gratefully acknowledge the financial support from the Norwegian Research Council, Equinor ASA, and ChampionX Norge AS.

Available from: 2024-04-25 Created: 2024-04-25 Last updated: 2024-04-25Bibliographically approved
Ruwoldt, J., Syverud, K. & Opedal, M. T. (2024). Purification of soda lignin. Sustainable Chemistry for the Environment, 6, Article ID 100102.
Open this publication in new window or tab >>Purification of soda lignin
2024 (English)In: Sustainable Chemistry for the Environment, ISSN 2949-8392, Vol. 6, article id 100102Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier B.V., 2024
National Category
Chemical Sciences
Identifiers
urn:nbn:se:ri:diva-73301 (URN)10.1016/j.scenv.2024.100102 (DOI)2-s2.0-85191834330 (Scopus ID)
Note

This work was carried out as a part of project “LignoWax – Green Wax Inhibitors and Production Chemicals based on Lignin”, Grant no. 326876. The authors gratefully acknowledge the financial support from the Norwegian Research Council, Equinor ASA, and ChampionX Norge AS. 

Available from: 2024-06-03 Created: 2024-06-03 Last updated: 2024-06-03Bibliographically approved
Ruwoldt, J., Chinga Carrasco, G. & Opedal, M. T. (2024). Sustainable Materials from Organosolv Fibers and Lignin, Kraft Fibers, and Their Blends. Polymers, 16(3), Article ID 377.
Open this publication in new window or tab >>Sustainable Materials from Organosolv Fibers and Lignin, Kraft Fibers, and Their Blends
2024 (English)In: Polymers, E-ISSN 2073-4360, Vol. 16, no 3, article id 377Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2024
Keywords
added-lignin thermoformed pulps, green materials, Kraft pulp, molded pulp, organosolv fibers, thermoforming, Anatomy, Contact Angle, Fibers, Stiffness, Tensile Strength, Wetting, Morphology, Surface morphology, Added-lignin thermoformed pulp, Fiber length, Fines content, Kraft fibers, Moulded pulp, Organosolv, Organosolv fiber, Organosolv lignin, Sustainable materials, Lignin
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-71954 (URN)10.3390/polym16030377 (DOI)2-s2.0-85184694922 (Scopus ID)
Funder
The Research Council of Norway, 257622
Note

 Correspondence Address: J. Ruwoldt; RISE PFI AS, Trondheim, Høgskoleringen 6B, 7491, Norway; This article was funded by the Research Council of Norway via the FME Centre for environmentally friendly energy research Bio4Fuel, grant number 257622.

Available from: 2024-02-27 Created: 2024-02-27 Last updated: 2024-02-27Bibliographically approved
Ruwoldt, J., Heen Blindheim, F. & Chinga Carrasco, G. (2023). Functional surfaces, films, and coatings with lignin - a critical review. RSC Advances, 13(18), 12529-12553
Open this publication in new window or tab >>Functional surfaces, films, and coatings with lignin - a critical review
2023 (English)In: RSC Advances, E-ISSN 2046-2069, Vol. 13, no 18, p. 12529-12553Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2023
Keywords
Additives, Biomolecules, Biopolymers, Corrosion resistant coatings, Paper and pulp industry, Wood, Coatings and films, Critical review, Films and coatings, Functional coating, Functional films, Functional surfaces, Polyaromatics, Surface coatings, Surface films, Versatile chemistry, Lignin
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:ri:diva-64674 (URN)10.1039/d2ra08179b (DOI)2-s2.0-85156140541 (Scopus ID)
Note

Correspondence Address: Ruwoldt, J.; RISE PFI AS, Norway; Funding details: Norges Forskningsråd; Funding text 1: The authors thank the Research Council of Norway for funding part of this work.

Available from: 2023-05-15 Created: 2023-05-15 Last updated: 2023-10-30Bibliographically approved
Pasquier, E., Skunde, R. & Ruwoldt, J. (2023). Influence of temperature and pressure during thermoforming of softwood pulp. Journal of Bioresources and Bioproducts, 8(4), 408-420
Open this publication in new window or tab >>Influence of temperature and pressure during thermoforming of softwood pulp
2023 (English)In: Journal of Bioresources and Bioproducts, ISSN 2369-9698, Vol. 8, no 4, p. 408-420Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
KeAi Communications Co., 2023
Keywords
Bleaching; Cellulose; Cleaning; Fibers; Hardwoods; Bleaching; Cellulose; Cleaning; Fibers; Hardwoods; Kraft pulp; Lignin; Pulp refining; Softwoods; Thin walled structures; Wood products; Chemi-thermomechanical softwood pulp; Condition; Fiber-based materials; Fibre-based materials; Moulded pulp; Northern bleached softwood kraft pulps; Softwood Pulps; Temperature and pressures; Thermo-mechanical; Tensile strength
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-67944 (URN)10.1016/j.jobab.2023.10.001 (DOI)2-s2.0-85173851362 (Scopus ID)
Note

The research was supported by the basic funding “ Grunnfinansering” of Norwegian Research Institutes by the Norwegian Government . The authors gratefully acknowledge the funding from the Research Council of Norway .

Available from: 2023-11-27 Created: 2023-11-27 Last updated: 2023-11-27Bibliographically approved
Heen Blindheim, F. & Ruwoldt, J. (2023). The Effect of Sample Preparation Techniques on Lignin Fourier Transform Infrared Spectroscopy. Polymers, 15(13), Article ID 2901.
Open this publication in new window or tab >>The Effect of Sample Preparation Techniques on Lignin Fourier Transform Infrared Spectroscopy
2023 (English)In: Polymers, E-ISSN 2073-4360, Vol. 15, no 13, article id 2901Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2023
Keywords
attenuated total reflectance, FTIR, KBr pellet, kraft lignin, lignin, lignin characterization, non-aqueous potentiometric titration, size exclusion chromatography, soda lignin, Amperometry, Pelleting, Potassium Compounds, Reflection, Volumetry, Biopolymers, Fourier transform infrared spectroscopy, Pelletizing, Potentiometers (electric measuring instruments), Signal to noise ratio, Titration, Voltammetry, Fourier transform infrared, Lignin characterizations, Non-aqueous, Potentiometric titrations, Size-exclusion chromatography, Bromine compounds
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-66003 (URN)10.3390/polym15132901 (DOI)2-s2.0-85164698254 (Scopus ID)
Note

Correspondence Address: J. Ruwoldt; RISE PFI AS, Trondheim, Høgskoleringen 6B, 7491, Norway; email: jost.ruwoldt@rise-pfi.no.  This work was carried out as a part of the project “LignoWax—Green Wax Inhibitors and Production Chemicals based on Lignin”, grant number 326876. The authors gratefully acknowledge the financial support from the Norwegian Research Council, Equinor ASA, and ChampionX Norge AS.

Available from: 2023-08-22 Created: 2023-08-22 Last updated: 2024-01-17Bibliographically approved
Ruwoldt, J. & Toven, K. (2022). Alternative wood treatment with blends of linseed oil, alcohols and pyrolysis oil. Journal of Bioresources and Bioproducts, 7(4), 278-287
Open this publication in new window or tab >>Alternative wood treatment with blends of linseed oil, alcohols and pyrolysis oil
2022 (English)In: Journal of Bioresources and Bioproducts, ISSN 2369-9698, Vol. 7, no 4, p. 278-287Article in journal (Refereed) Published
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)

Place, publisher, year, edition, pages
KeAi Communications Co., 2022
Keywords
Linseed oil treatment, Pyrolysis oil, Royal process, Wood impregnation, Wood treatment, Impregnation, Pyrolysis, Wood, ITS applications, Linseed oil, Naphthenic oil, Oil treatment, Primary alcohols, Wood-treatment, Oilseeds
National Category
Energy Engineering
Identifiers
urn:nbn:se:ri:diva-60191 (URN)10.1016/j.jobab.2022.07.002 (DOI)2-s2.0-85136758332 (Scopus ID)
Available from: 2022-09-29 Created: 2022-09-29 Last updated: 2023-07-06Bibliographically approved
Dudek, M., Ruwoldt, J. & Øye, G. (2022). Characterization and assessment of wax and wax inhibitors systems in microfluidic oil-in-water coalescence experiments. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 636, Article ID 128186.
Open this publication in new window or tab >>Characterization and assessment of wax and wax inhibitors systems in microfluidic oil-in-water coalescence experiments
2022 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 636, article id 128186Article in journal (Refereed) Published
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)

Place, publisher, year, edition, pages
Elsevier B.V., 2022
Keywords
Coalescence, Emulsion stability, Microfluidics, Produced water, Production chemicals, Wax inhibitor, Additives, Block copolymers, Drops, Emulsions, Indicators (chemical), Morphology, Ostwald ripening, Physicochemical properties, Separation, Stability, Styrene, Chemical compositions, Inhibitor system, Oil droplets, Oil-in-water, Process condition, Produced water treatments, Production chemical, Separation performance, Wax inhibitors, Emulsification
National Category
Physical Chemistry
Identifiers
urn:nbn:se:ri:diva-57909 (URN)10.1016/j.colsurfa.2021.128186 (DOI)2-s2.0-85121961297 (Scopus ID)
Note

Funding details: Norges Teknisk-Naturvitenskapelige Universitet, NTNU; Funding details: Norges Forskningsråd; Funding text 1: This work was carried out as a part of SUBPRO, a Research-based Innovation Centre within Subsea Production and Processing. The authors gratefully acknowledge the financial support from SUBPRO, which is financed by the Research Council of Norway , major industry partners and NTNU .

Available from: 2022-01-10 Created: 2022-01-10 Last updated: 2023-05-23Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0583-224x

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