Ola Sundman - Academia.edu (original) (raw)

Papers by Ola Sundman

Journal of membrane science, May 1, 2024

bioRxiv (Cold Spring Harbor Laboratory), Aug 28, 2021

Important structures and functions within living organisms rely on naturally fluorescent polymeri... more Important structures and functions within living organisms rely on naturally fluorescent polymeric molecules such as collagen, keratin, elastin, resilin, or lignin. Theoretical physics predict that fluorescence lifetime of these polymers is related to their chemical composition. We verified this prediction for lignin, a major structural element in plant cell walls and one of the most abundant components of wood. Lignin is composed of different types of phenylpropanoid units, and its composition affects its properties, biological functions, and the utilization of wood biomass. We carried out fluorescence lifetime imaging microscopy (FLIM) measurements of wood cell wall lignin in a population of 90 hybrid aspen trees genetically engineered to display differences in cell wall chemistry and structure. We also measured wood cell wall composition by classical analytical methods in the wood cell walls of these trees. Using statistical modelling and machine learning algorithms, we identified parameters of fluorescence lifetime that predict the content of S-type and G-type lignin units, the two main types of units in the lignin of angiosperm plants. Finally, we show how quantitative measurements of lignin chemical composition by FLIM can reveal the dynamics of lignin biosynthesis in two different biological contexts, including in vivo while lignin is being synthesized in the walls of living cells.

Acid/base and metal ion adsorption properties have been investigated for a range of chemically mo... more Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K+, Na+, Mg2+, Ca2+ and Cu2+, provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca2+ and Cu2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. The interactions occurring between the polycation GaO4Al12(OH)24(H2O)127+ and fibre materials were studied by both adsorption and spectroscopic measurements. These indicate that GaO4Al12(OH)24(H2O)127+ is surprisingly stable in fibre suspensions and that intact GaO4Al12(OH)24(H2O)127+- ions are strongly adsorbed onto the fibres. Also for this ion, specific interactions has to be considered, since the strong adsorption registered was too strong to be explained by Donnan equilibria. In the thesis, the stochiometric composition and an equilibrium constant characterising these interactions is presented.

Cellulose, Nov 10, 2013

The adsorption of four commercial nonionic cellulose derivatives onto two different model surface... more The adsorption of four commercial nonionic cellulose derivatives onto two different model surfaces of cellulose fibres has been studied with surface plasmon reflectance. The model surfaces of cellulose were ultrathin films of either nano fibrillated cellulose or regenerated cellulose on Au(s). Partial least squares models were used in the analysis of the data and it was found that the type of cellulose model surface seems to be most important for both the total adsorption and the initial adsorption rate of the studied cellulose derivatives. It is believed that this can be explained by morphological differences between the surfaces, and it was found that the properties of the cellulose derivatives that affect the adsorption of the two types of cellulose surface differ. For adsorption onto a NFC-based model surface, the type of cellulose derivative and the polydispersity index (PDI) of the cellulose derivative seem to be the two most important variables for the observed adsorption of these cellulose derivatives. For the regenerated cellulose surface the three most important variables are the M n of the cellulose derivatives, the DS NMR of the methyl celluloses, and PDI of the cellulose derivatives. Thus the adsorption of cellulose derivatives on the NFCbased cellulose model surface is strongly affected by the type of substituent, while the same cannot be said for a surface regenerated from N-methylmorpholine-N-oxide. Additionally, the DS NMR of methyl celluloses affects their adsorption differently on the investigated cellulose model surfaces.

Bioresource Technology, Oct 1, 2011

The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolyme... more The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolymers, CDACs, synthesized by cationizing dialdehyde cellulose in mild aqueous solution was studied in a kaolin suspension. In particular, the role of CDAC dosage and solution pH, NaCl concentration, and temperature were clarified. In addition, the initial apparent charge densities (CDs), particle sizes, f-potential, and stability of CDs were determined. CDACs possessed a high flocculation activity in neutral and acidic solutions, but a significant decrease was observed in alkaline solutions (pH >9). This was also seen as a decline in the apparent CD and particle size of the CDACs in alkaline conditions. The measurements also indicated that the apparent CD decreased to a constant level of 3 mmol/g in aqueous solutions. However, no notable decrease in flocculation performance was obtained after several days of storage. Moreover, the variation of NaCl concentration and temperature did not affect the flocculation activity.

Cellulose Chemistry and Technology, 2015

This paper offers an evaluation of different methods for synthesizing benzyl cellulose and of how... more This paper offers an evaluation of different methods for synthesizing benzyl cellulose and of how they affect characteristics such as solubility, degree of substitution, thermal stability and molecular weight of the products. Benzyl celluloses with degrees of substitution between 0.1 and 2.5 were synthesised from microcrystalline cellulose in (1) aqueous NaOH/Urea and (2) dimethyl sulfoxide/tert-butyl ammonium fluoride (DMSO/TBAF) systems in order to evaluate the different properties of the benzyl celluloses of low degree of substitution. In contrast to previous findings in the literature, both systems yielded soluble benzyl celluloses at degrees of substitution <0.5. Also in contrast to the literature, the low degree of substitution benzyl celluloses from both systems showed similar thermal properties. The filtration of the benzyl celluloses in DMSO/TBAF solutions before precipitation gave significantly higher solubility of the products and increased their thermal stability. The molecular weights of the benzyl celluloses of low degree of substitution (0.4 < DS < 1.25) were similar between the systems and differed in the range of one order of magnitude from the molecular weights of the higher degree of substitution benzyl celluloses. 13 C-NMR data indicated differences in the substitution pattern between the two systems.

Nordic Pulp & Paper Research Journal, Dec 1, 2005

To evaluate the capacity of different thermodynamic models to mimic the build-up of charge on ful... more To evaluate the capacity of different thermodynamic models to mimic the build-up of charge on fully bleached softwood fibres as a function of-log[H + ] and ionic strength (0.01-0.6 M NaCl), the model of an Ideal Monoprotic Acid, the Constant Capacitance Model (CCM), the Basic Stern Model (BSM), and the Diffuse Layer Model (DLM) were compared. The Ideal Monoprotic Acid, IMA, model consistently yielded a too steep increase in the build up of charge with-log[H + ] and thereby indicated the need for applying a surface potential model. The "best" of these, with respect to describing the experimental data, was found to be the Constant Capacitance Model, which utilises an individual equilibrium constant and an individual capacitance value at each ionic strength modelled. However, the Basic Stern Model, which uses only two variables over the entire ionic strength interval, was found to describe data almost as well. Therefore, in modelling applications where a variation in the salt concentration is significant, the Basic Stern Model must be judged as being superior to the Constant Capacitance Model. As for the IMA model, the Diffuse Layer Model, finally, was found to yield a too steep increase in the fibre charge with rising-log[H + ]. Nevertheless, it was found to model the variation of the apparent acidity with ionic strength, relatively well.

Carbohydrate Polymers, Aug 1, 2014

The aim of this work was to study the effect of solution conditions and polysaccharide structure ... more The aim of this work was to study the effect of solution conditions and polysaccharide structure on their Layer-by-Layer (LbL) deposition on nanofibrillated cellulose (NFC). Multilayer build-up of cellulose derivatives and chitosan on NFC model surfaces was studied using Quartz Crystal Microbalance with Dissipation (QCM-D) and Colloidal Probe Microscopy (CPM). The type of cationic polysaccharide was found to significantly affect the multilayer build-up and surface interactions. Cationic cellulose derivative quaternized hydroxyethyl cellulose ethoxylate (HECE) formed highly water-swollen layers with carboxymethyl cellulose (CMC), and the build-up was markedly influenced by both the ionic strength and pH. The ionic strength did not significantly influence the multilayer build-up of chitosan-CMC system, and adsorbed chitosan layers decreased the viscoelasticity of the system. Based on the results, it was also confirmed that electrostatic interaction is not the only driving force in case of the build-up of polysaccharide multilayers on nanofibrillated cellulose.

Carbohydrate Polymers, Oct 1, 2015

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Dissolution of cellulose in newly synthesized ionic liquids was studied.  At 120 °C, [AMMorp][OAc] could dissolve 30 wt%, 28 wt% and 25 wt% of cellulose with degree of polymerization (DPn)-789, 1644 and 2082 respectively, in 20 min.  Importantly, 25 wt% cellulose with very high DP (2082) could be dissolved.  Structure and morphology of regenerated cellulose films were determined.  No discernible changes occurred in terms of the degree of polymerization of the different celluloses after regeneration.  Efficient recovery of [AMMorp][OAc] was demonstrated using water as an antisolvent.

Bioresources, Nov 4, 2022

A cellulose ether that is easier to melt than benzyl cellulose was produced from the lignin degra... more A cellulose ether that is easier to melt than benzyl cellulose was produced from the lignin degradation product veratryl alcohol. Veratryl chloride and bromide were synthesized from the alcohol, and these two chemicals were used to react with Avicel® cellulose to form the novel cellulose ether veratryl cellulose (VC). Spectroscopic characterisation techniques (1 H NMR, FTIR) indicated the successful conversion of Avicel® cellulose to the cellulose ether VC, by both routes, at a degree of substitution of 1.4 to 1.6. Melting measurements of the VC samples showed a gradual softening from approximately 110 °C; the VC was melted below 200 °C. XRD analysis confirmed that the chemical treatments affect the degree of crystallinity. Size exclusion chromatography results showed that the products differ remarkably in molecular weight. The VC synthesized with veratryl chloride degraded almost twice as much as when veratryl bromide were used. The cellulose ethers were soluble in DMSO, DMAc, and CHCl3.

Cellulose Chemistry and Technology, May 5, 2022

With a multivariate approach, we investigate and correlate the effect of mercerization conditions... more With a multivariate approach, we investigate and correlate the effect of mercerization conditions on the properties of a cellulose ether. We have chosen to work with carboxymethylcellulose (CMC) for analytical reasons. As expected, the DS was found to increase when the NaOH/AGU (anhydroglucose unit) stoichiometric ratio (r) was increased (range 1.0-1.3) and [NaOH] was decreased (range 50-30%). However, such changes also favoured the formation of unwanted side products. Decreased (r) and increased [NaOH] resulted in increased heterogeneity, and thus the quantities of insoluble particles and unreacted chemicals also increased. As another result, the prediction between mercerisation and synthesis weakens. Consequently, a DS of 0.18-0.7 was obtained; the measured solubility was much lower than expected. A non-statistical distribution of substituents was further found. Interestingly, the relative importance of substitution at increases with an increased [NaOH].

ACS Sustainable Chemistry & Engineering, Dec 11, 2021

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Applied Surface Science, Jun 1, 2010

Fermentation, Jun 10, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Nordic Pulp & Paper Research Journal, Aug 1, 2006

The aim of this work was to characterize a series of carboxymethylated pulps of various degrees o... more The aim of this work was to characterize a series of carboxymethylated pulps of various degrees of substitution (40-280 µmol/g) with respect to their acid/base and metal adsorption qualities. The study was performed using potentiometric titrations, batch experiments and AAS/AES analyses. With respect to the acid/base properties of the different pulps, the study has shown that the Basic Stern Model and the Constant Capacitance Model both can be used to describe the different pulps in the region of interest. For the most highly substituted pulp, however, the CCM should preferably be used to describe the acid/base properties at low pH. The metal ion adsorption study comprised a simultaneous presence of four metal ion, namely Na + , K + , Ca 2+ and Mg 2+. With respect to these interactions data showed that the Donnan ion exchange model could well explain the simultaneous adsorption of all four metal ions, independently of the degree of "CMC substitution". The fit of the Donnan model to the data was approximately equal independently on whether the Constant Capacitance Model or the Basic Stern Model was used to model the pH-dependent fibre charge. The conclusion to be drawn from this study is that the Donnan model can be applied within a wide range of pulp charge, as long as there are only mono-carboxylate groups on the fibre and these are characterised by a valid acid/base model.

Acid/base and metal ion adsorption properties have been investigated for a range of chemically mo... more Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K + , Na + , Mg 2+ , Ca 2+ and Cu 2+ , provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca 2+ and Cu 2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu 2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu 2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. v

A compilation of the applied experimental conditions when studying metal ion adsorption onto kraf... more A compilation of the applied experimental conditions when studying metal ion adsorption onto kraft fibres, and the resulting conclusion, revealed that the ionic strength conditions used during the experiments were an important dividing factor. At low ionic strengths, the conclusion has regularly been that the Donnan ionexchange model could correctly predict the adsorption while, at higher ionic strengths, it has often been concluded that the formation of specific metal-ion fibre complexes must be assumed. To study this apparent influence from the presence of monovalent sodium ions, Cu K-edge EXAFS spectra of Cu 2+ ions adsorbed to kraft fibres were collected in media of "0" to 100 mM NaCl. Combined with previous data, these measurements confirmed that at very low ionic strength, the importance of specific interactions between the chemically modified cellulose fibres and the Cu(II) ions significantly decreased. For a detailed description of the adsorption phenomenon, both types of interactions must be considered simultaneously. For most technical and engineering applications, however, the Donnan model can be used at low ionic strength conditions, i.e. I ≲ 10 mM. At higher ionic strengths, though, the inclusion of specific complexes in the model is necessary for correctly describing the adsorption of di-and trivalent cations with strong complex forming properties.

Plant Journal, Jul 10, 2020

Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load-beari... more Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load-bearing polymers in wood. CELLULOSE SYNTHASE INTERACTING1 (CSI1) connects CSCs with cortical microtubules, which align with cellulose microfibrils. Mechanical properties of wood are dependent on cellulose microfibril alignment and structure in the cell walls, but the molecular mechanism(s) defining these features is unknown. Herein, we investigated the role of CSI1 in hybrid aspen (Populus tremula × Populus tremuloides) by characterizing transgenic lines with significantly reduced CSI1 transcript abundance. Reduction in leaves (50-80%) caused leaf twisting and misshaped pavement cells, while reduction (70-90%) in developing xylem led to impaired mechanical wood properties evident as a decrease in the elastic modulus and rupture. X-ray diffraction measurements indicate that microfibril angle was not impacted by the altered CSI1 abundance in developing wood fibres. Instead, the augmented wood phenotype of the transgenic trees was associated with a reduced cellulose degree of polymerization. These findings establish a function for CSI1 in wood mechanics and in defining leaf cell shape. Furthermore, the results imply that the microfibril angle in wood is defined by CSI1 independent mechanism(s).

Energy & Fuels, Nov 18, 2010

The previously presented synthetic tetra-acid model compound BP10 was used to investigate the che... more The previously presented synthetic tetra-acid model compound BP10 was used to investigate the chemistry behind the formation of metal naphthenate deposits. The interactions between BP10 and the cations Ba 2þ , Ca 2þ , H þ , Mg 2þ , and Sr 2þ were investigated using potentiometric titrations, metal ion depletion by inductively coupled plasma-atomic emission spectrometry (ICP-AES), pH measurements, and elemental analysis of precipitates, in 20-600 mM NaCl ionic medium. The interactions of BP10 with the monovalent Na þ are discussed on the basis of a previous study. The data given indicate that Ca 2þ shows the strongest affinity toward BP10 and Ba 2þ , and Sr 2þ form approximately equally stable solid phases with BP10, while Mg 2þ is less tightly bound to the tetra-acid. H þ interacts more strongly than the Me 2þ ions, and Na þ shows a rather small affinity for BP10. No soluble complexes could be detected, and all products in the chemical reactions are therefore believed to be solid materials. We suggest that BP10 show the following preference of cations: H þ. Ca 2þ > Ba 2þ ≈ Sr 2þ > Mg 2þ. Na þ. This order could be due to the hydration state and size of the cations. In comparison to typical concentrations found of each in saline water, it is proposed that the dominance of Ca 2þ in naphthenate deposits is dependent upon both availability and selectivity.

Journal of membrane science, May 1, 2024

bioRxiv (Cold Spring Harbor Laboratory), Aug 28, 2021

Important structures and functions within living organisms rely on naturally fluorescent polymeri... more Important structures and functions within living organisms rely on naturally fluorescent polymeric molecules such as collagen, keratin, elastin, resilin, or lignin. Theoretical physics predict that fluorescence lifetime of these polymers is related to their chemical composition. We verified this prediction for lignin, a major structural element in plant cell walls and one of the most abundant components of wood. Lignin is composed of different types of phenylpropanoid units, and its composition affects its properties, biological functions, and the utilization of wood biomass. We carried out fluorescence lifetime imaging microscopy (FLIM) measurements of wood cell wall lignin in a population of 90 hybrid aspen trees genetically engineered to display differences in cell wall chemistry and structure. We also measured wood cell wall composition by classical analytical methods in the wood cell walls of these trees. Using statistical modelling and machine learning algorithms, we identified parameters of fluorescence lifetime that predict the content of S-type and G-type lignin units, the two main types of units in the lignin of angiosperm plants. Finally, we show how quantitative measurements of lignin chemical composition by FLIM can reveal the dynamics of lignin biosynthesis in two different biological contexts, including in vivo while lignin is being synthesized in the walls of living cells.

Acid/base and metal ion adsorption properties have been investigated for a range of chemically mo... more Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K+, Na+, Mg2+, Ca2+ and Cu2+, provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca2+ and Cu2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. The interactions occurring between the polycation GaO4Al12(OH)24(H2O)127+ and fibre materials were studied by both adsorption and spectroscopic measurements. These indicate that GaO4Al12(OH)24(H2O)127+ is surprisingly stable in fibre suspensions and that intact GaO4Al12(OH)24(H2O)127+- ions are strongly adsorbed onto the fibres. Also for this ion, specific interactions has to be considered, since the strong adsorption registered was too strong to be explained by Donnan equilibria. In the thesis, the stochiometric composition and an equilibrium constant characterising these interactions is presented.

Cellulose, Nov 10, 2013

The adsorption of four commercial nonionic cellulose derivatives onto two different model surface... more The adsorption of four commercial nonionic cellulose derivatives onto two different model surfaces of cellulose fibres has been studied with surface plasmon reflectance. The model surfaces of cellulose were ultrathin films of either nano fibrillated cellulose or regenerated cellulose on Au(s). Partial least squares models were used in the analysis of the data and it was found that the type of cellulose model surface seems to be most important for both the total adsorption and the initial adsorption rate of the studied cellulose derivatives. It is believed that this can be explained by morphological differences between the surfaces, and it was found that the properties of the cellulose derivatives that affect the adsorption of the two types of cellulose surface differ. For adsorption onto a NFC-based model surface, the type of cellulose derivative and the polydispersity index (PDI) of the cellulose derivative seem to be the two most important variables for the observed adsorption of these cellulose derivatives. For the regenerated cellulose surface the three most important variables are the M n of the cellulose derivatives, the DS NMR of the methyl celluloses, and PDI of the cellulose derivatives. Thus the adsorption of cellulose derivatives on the NFCbased cellulose model surface is strongly affected by the type of substituent, while the same cannot be said for a surface regenerated from N-methylmorpholine-N-oxide. Additionally, the DS NMR of methyl celluloses affects their adsorption differently on the investigated cellulose model surfaces.

Bioresource Technology, Oct 1, 2011

The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolyme... more The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolymers, CDACs, synthesized by cationizing dialdehyde cellulose in mild aqueous solution was studied in a kaolin suspension. In particular, the role of CDAC dosage and solution pH, NaCl concentration, and temperature were clarified. In addition, the initial apparent charge densities (CDs), particle sizes, f-potential, and stability of CDs were determined. CDACs possessed a high flocculation activity in neutral and acidic solutions, but a significant decrease was observed in alkaline solutions (pH >9). This was also seen as a decline in the apparent CD and particle size of the CDACs in alkaline conditions. The measurements also indicated that the apparent CD decreased to a constant level of 3 mmol/g in aqueous solutions. However, no notable decrease in flocculation performance was obtained after several days of storage. Moreover, the variation of NaCl concentration and temperature did not affect the flocculation activity.

Cellulose Chemistry and Technology, 2015

This paper offers an evaluation of different methods for synthesizing benzyl cellulose and of how... more This paper offers an evaluation of different methods for synthesizing benzyl cellulose and of how they affect characteristics such as solubility, degree of substitution, thermal stability and molecular weight of the products. Benzyl celluloses with degrees of substitution between 0.1 and 2.5 were synthesised from microcrystalline cellulose in (1) aqueous NaOH/Urea and (2) dimethyl sulfoxide/tert-butyl ammonium fluoride (DMSO/TBAF) systems in order to evaluate the different properties of the benzyl celluloses of low degree of substitution. In contrast to previous findings in the literature, both systems yielded soluble benzyl celluloses at degrees of substitution <0.5. Also in contrast to the literature, the low degree of substitution benzyl celluloses from both systems showed similar thermal properties. The filtration of the benzyl celluloses in DMSO/TBAF solutions before precipitation gave significantly higher solubility of the products and increased their thermal stability. The molecular weights of the benzyl celluloses of low degree of substitution (0.4 < DS < 1.25) were similar between the systems and differed in the range of one order of magnitude from the molecular weights of the higher degree of substitution benzyl celluloses. 13 C-NMR data indicated differences in the substitution pattern between the two systems.

Nordic Pulp & Paper Research Journal, Dec 1, 2005

To evaluate the capacity of different thermodynamic models to mimic the build-up of charge on ful... more To evaluate the capacity of different thermodynamic models to mimic the build-up of charge on fully bleached softwood fibres as a function of-log[H + ] and ionic strength (0.01-0.6 M NaCl), the model of an Ideal Monoprotic Acid, the Constant Capacitance Model (CCM), the Basic Stern Model (BSM), and the Diffuse Layer Model (DLM) were compared. The Ideal Monoprotic Acid, IMA, model consistently yielded a too steep increase in the build up of charge with-log[H + ] and thereby indicated the need for applying a surface potential model. The "best" of these, with respect to describing the experimental data, was found to be the Constant Capacitance Model, which utilises an individual equilibrium constant and an individual capacitance value at each ionic strength modelled. However, the Basic Stern Model, which uses only two variables over the entire ionic strength interval, was found to describe data almost as well. Therefore, in modelling applications where a variation in the salt concentration is significant, the Basic Stern Model must be judged as being superior to the Constant Capacitance Model. As for the IMA model, the Diffuse Layer Model, finally, was found to yield a too steep increase in the fibre charge with rising-log[H + ]. Nevertheless, it was found to model the variation of the apparent acidity with ionic strength, relatively well.

Carbohydrate Polymers, Aug 1, 2014

The aim of this work was to study the effect of solution conditions and polysaccharide structure ... more The aim of this work was to study the effect of solution conditions and polysaccharide structure on their Layer-by-Layer (LbL) deposition on nanofibrillated cellulose (NFC). Multilayer build-up of cellulose derivatives and chitosan on NFC model surfaces was studied using Quartz Crystal Microbalance with Dissipation (QCM-D) and Colloidal Probe Microscopy (CPM). The type of cationic polysaccharide was found to significantly affect the multilayer build-up and surface interactions. Cationic cellulose derivative quaternized hydroxyethyl cellulose ethoxylate (HECE) formed highly water-swollen layers with carboxymethyl cellulose (CMC), and the build-up was markedly influenced by both the ionic strength and pH. The ionic strength did not significantly influence the multilayer build-up of chitosan-CMC system, and adsorbed chitosan layers decreased the viscoelasticity of the system. Based on the results, it was also confirmed that electrostatic interaction is not the only driving force in case of the build-up of polysaccharide multilayers on nanofibrillated cellulose.

Carbohydrate Polymers, Oct 1, 2015

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Dissolution of cellulose in newly synthesized ionic liquids was studied.  At 120 °C, [AMMorp][OAc] could dissolve 30 wt%, 28 wt% and 25 wt% of cellulose with degree of polymerization (DPn)-789, 1644 and 2082 respectively, in 20 min.  Importantly, 25 wt% cellulose with very high DP (2082) could be dissolved.  Structure and morphology of regenerated cellulose films were determined.  No discernible changes occurred in terms of the degree of polymerization of the different celluloses after regeneration.  Efficient recovery of [AMMorp][OAc] was demonstrated using water as an antisolvent.

Bioresources, Nov 4, 2022

A cellulose ether that is easier to melt than benzyl cellulose was produced from the lignin degra... more A cellulose ether that is easier to melt than benzyl cellulose was produced from the lignin degradation product veratryl alcohol. Veratryl chloride and bromide were synthesized from the alcohol, and these two chemicals were used to react with Avicel® cellulose to form the novel cellulose ether veratryl cellulose (VC). Spectroscopic characterisation techniques (1 H NMR, FTIR) indicated the successful conversion of Avicel® cellulose to the cellulose ether VC, by both routes, at a degree of substitution of 1.4 to 1.6. Melting measurements of the VC samples showed a gradual softening from approximately 110 °C; the VC was melted below 200 °C. XRD analysis confirmed that the chemical treatments affect the degree of crystallinity. Size exclusion chromatography results showed that the products differ remarkably in molecular weight. The VC synthesized with veratryl chloride degraded almost twice as much as when veratryl bromide were used. The cellulose ethers were soluble in DMSO, DMAc, and CHCl3.

Cellulose Chemistry and Technology, May 5, 2022

With a multivariate approach, we investigate and correlate the effect of mercerization conditions... more With a multivariate approach, we investigate and correlate the effect of mercerization conditions on the properties of a cellulose ether. We have chosen to work with carboxymethylcellulose (CMC) for analytical reasons. As expected, the DS was found to increase when the NaOH/AGU (anhydroglucose unit) stoichiometric ratio (r) was increased (range 1.0-1.3) and [NaOH] was decreased (range 50-30%). However, such changes also favoured the formation of unwanted side products. Decreased (r) and increased [NaOH] resulted in increased heterogeneity, and thus the quantities of insoluble particles and unreacted chemicals also increased. As another result, the prediction between mercerisation and synthesis weakens. Consequently, a DS of 0.18-0.7 was obtained; the measured solubility was much lower than expected. A non-statistical distribution of substituents was further found. Interestingly, the relative importance of substitution at increases with an increased [NaOH].

ACS Sustainable Chemistry & Engineering, Dec 11, 2021

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Applied Surface Science, Jun 1, 2010

Fermentation, Jun 10, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Nordic Pulp & Paper Research Journal, Aug 1, 2006

The aim of this work was to characterize a series of carboxymethylated pulps of various degrees o... more The aim of this work was to characterize a series of carboxymethylated pulps of various degrees of substitution (40-280 µmol/g) with respect to their acid/base and metal adsorption qualities. The study was performed using potentiometric titrations, batch experiments and AAS/AES analyses. With respect to the acid/base properties of the different pulps, the study has shown that the Basic Stern Model and the Constant Capacitance Model both can be used to describe the different pulps in the region of interest. For the most highly substituted pulp, however, the CCM should preferably be used to describe the acid/base properties at low pH. The metal ion adsorption study comprised a simultaneous presence of four metal ion, namely Na + , K + , Ca 2+ and Mg 2+. With respect to these interactions data showed that the Donnan ion exchange model could well explain the simultaneous adsorption of all four metal ions, independently of the degree of "CMC substitution". The fit of the Donnan model to the data was approximately equal independently on whether the Constant Capacitance Model or the Basic Stern Model was used to model the pH-dependent fibre charge. The conclusion to be drawn from this study is that the Donnan model can be applied within a wide range of pulp charge, as long as there are only mono-carboxylate groups on the fibre and these are characterised by a valid acid/base model.

Acid/base and metal ion adsorption properties have been investigated for a range of chemically mo... more Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K + , Na + , Mg 2+ , Ca 2+ and Cu 2+ , provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca 2+ and Cu 2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu 2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu 2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. v

A compilation of the applied experimental conditions when studying metal ion adsorption onto kraf... more A compilation of the applied experimental conditions when studying metal ion adsorption onto kraft fibres, and the resulting conclusion, revealed that the ionic strength conditions used during the experiments were an important dividing factor. At low ionic strengths, the conclusion has regularly been that the Donnan ionexchange model could correctly predict the adsorption while, at higher ionic strengths, it has often been concluded that the formation of specific metal-ion fibre complexes must be assumed. To study this apparent influence from the presence of monovalent sodium ions, Cu K-edge EXAFS spectra of Cu 2+ ions adsorbed to kraft fibres were collected in media of "0" to 100 mM NaCl. Combined with previous data, these measurements confirmed that at very low ionic strength, the importance of specific interactions between the chemically modified cellulose fibres and the Cu(II) ions significantly decreased. For a detailed description of the adsorption phenomenon, both types of interactions must be considered simultaneously. For most technical and engineering applications, however, the Donnan model can be used at low ionic strength conditions, i.e. I ≲ 10 mM. At higher ionic strengths, though, the inclusion of specific complexes in the model is necessary for correctly describing the adsorption of di-and trivalent cations with strong complex forming properties.

Plant Journal, Jul 10, 2020

Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load-beari... more Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load-bearing polymers in wood. CELLULOSE SYNTHASE INTERACTING1 (CSI1) connects CSCs with cortical microtubules, which align with cellulose microfibrils. Mechanical properties of wood are dependent on cellulose microfibril alignment and structure in the cell walls, but the molecular mechanism(s) defining these features is unknown. Herein, we investigated the role of CSI1 in hybrid aspen (Populus tremula × Populus tremuloides) by characterizing transgenic lines with significantly reduced CSI1 transcript abundance. Reduction in leaves (50-80%) caused leaf twisting and misshaped pavement cells, while reduction (70-90%) in developing xylem led to impaired mechanical wood properties evident as a decrease in the elastic modulus and rupture. X-ray diffraction measurements indicate that microfibril angle was not impacted by the altered CSI1 abundance in developing wood fibres. Instead, the augmented wood phenotype of the transgenic trees was associated with a reduced cellulose degree of polymerization. These findings establish a function for CSI1 in wood mechanics and in defining leaf cell shape. Furthermore, the results imply that the microfibril angle in wood is defined by CSI1 independent mechanism(s).

Energy & Fuels, Nov 18, 2010

The previously presented synthetic tetra-acid model compound BP10 was used to investigate the che... more The previously presented synthetic tetra-acid model compound BP10 was used to investigate the chemistry behind the formation of metal naphthenate deposits. The interactions between BP10 and the cations Ba 2þ , Ca 2þ , H þ , Mg 2þ , and Sr 2þ were investigated using potentiometric titrations, metal ion depletion by inductively coupled plasma-atomic emission spectrometry (ICP-AES), pH measurements, and elemental analysis of precipitates, in 20-600 mM NaCl ionic medium. The interactions of BP10 with the monovalent Na þ are discussed on the basis of a previous study. The data given indicate that Ca 2þ shows the strongest affinity toward BP10 and Ba 2þ , and Sr 2þ form approximately equally stable solid phases with BP10, while Mg 2þ is less tightly bound to the tetra-acid. H þ interacts more strongly than the Me 2þ ions, and Na þ shows a rather small affinity for BP10. No soluble complexes could be detected, and all products in the chemical reactions are therefore believed to be solid materials. We suggest that BP10 show the following preference of cations: H þ. Ca 2þ > Ba 2þ ≈ Sr 2þ > Mg 2þ. Na þ. This order could be due to the hydration state and size of the cations. In comparison to typical concentrations found of each in saline water, it is proposed that the dominance of Ca 2þ in naphthenate deposits is dependent upon both availability and selectivity.