umu.sePublikasjoner
Endre søk
Link to record
Permanent link

Direct link
BETA
Albán Reyes, Diana Carolina
Alternativa namn
Publikasjoner (7 av 7) Visa alla publikasjoner
Albán Reyes, D. C., Stridh, K., de Wit, P. P. & Sundman, O. (2019). Is there a diffusion of alkali in the activation of dissolving cellulose pulp at low NAOH stoichiometric excess?. Cellulose (London), 26(2), 1297-1308
Åpne denne publikasjonen i ny fane eller vindu >>Is there a diffusion of alkali in the activation of dissolving cellulose pulp at low NAOH stoichiometric excess?
2019 (engelsk)Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 2, s. 1297-1308Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We conducted a quantitative study, following the degree of activation (i.e. the transformation to alkali cellulose, denoted as DoA) over time for dissolving cellulose pulp treated with different [NaOH] at low NaOH/anhydroglucose unit stoichiometric ratio (denoted as (r) ≤ 2.6). Our quantitative approach was based on Raman spectroscopy data, evaluated by partial least squares regression modelling. The results show strong influence of the (r) on DoA (increasing from DoA= 45% at (r) = 0.8, to DoA = 85% at (r) = 2.6), and its complex dependence on [NaOH]. At (r) = 0.8 the highest DoA (DoA ≳ 60%) was found at 30% [NaOH], while at (r) =1.3 it was found at 20% [NaOH] (DoA ≳ 80%). Although activation of cellulose happens in minutes at the studied temperature (30 °C), it was found that the reaction may be slow when a low (r) is used. A gradual increase of the DoA from ≈ 30% to ≈ 70% in time was seen when samples were activated with 30% [NaOH] at (r) = 0.8. At the same (r), a similar increase of DoA from ≈ 30 % to ≈ 60 % was also observed when 40% [NaOH] was used. Slow diffusion of NaOH through poorly swollen cellulose fibres is proposed as an explanation for this phenomenon. Lastly, solid-state CP/MAS NMR measurements suggest that at a fixed temperature, the Na-Cell allomorph mostly depends on [NaOH]. However, in the transition area between Na-Cell I and Na-Cell II, its influence might be affected by (r). 

sted, utgiver, år, opplag, sider
Springer, 2019
Emneord
Alkali cellulose, Activation, Polymorphs, Cellulose ether, Diffusion
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-153345 (URN)10.1007/s10570-018-2104-9 (DOI)000459455200045 ()
Prosjekter
Bio4Energy
Tilgjengelig fra: 2018-11-16 Laget: 2018-11-16 Sist oppdatert: 2019-08-30bibliografisk kontrollert
Reyes Forsberg, D. C. (2018). Experimental study of alkalinisation of cellulose in industrial relevant conditions. (Doctoral dissertation). Umeå: Umeå universitet
Åpne denne publikasjonen i ny fane eller vindu >>Experimental study of alkalinisation of cellulose in industrial relevant conditions
2018 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Mercerisation of cellulose pulp with a solution of NaOH is the first step of manufacturing cellulose-based value-added products, e.g. viscose fibres and cellulose ethers. During this process, cellulose transforms into a swollen crystalline structure, alkali cellulose (Na-Cell). This increases the reactivity of the cellulose and makes it more accessible for reagents to penetrate and react with the hydroxyl groups. The mercerisation conditions are known to affect the degree of alkalinisation of cellulose as well as the final products. The main objective of this thesis is to investigate how the alkalinisation of softwood sulphite dissolving cellulose pulp is influenced by the co-variation of process variables in the mercerisation in industrial relevant conditions, for both viscose and cellulose ether production. This objective was achieved by quantitative analysis of the effect of simultaneous variation of a set of key parameters on the degree of alkalinisation (i.e. degree of activation, DoA) of the chosen dissolving pulp. Quantitative measurements were performed using Raman spectroscopy data, evaluated by partial least squares (PLS) regression. For mercerisation at viscose production conditions, the effect of studied variables on mass yield was also considered. In the case of mercerisation at ether processing conditions, formation of alkali cellulose at a fixed temperature was included. The knowledge obtained on mercerisation under ether processing conditions was then applied for preparation of the ionic cellulose ether carboxymethylcellulose (CMC).

The overall results show that temperature has a strong effect on DoA and mass yield for mercerised samples under steeping conditions. Measured DoA decreases as the temperature increases from 20 to 70 °C. Mass yield correlates positively with the temperature up to 45-50 °C in the PLS model, after which the relation is negative. The [NaOH] and reaction time show a complex dependence of other variables. At mercerisation conditions for cellulose ether production, the NaOH/AGU stoichiometric ratio, denoted as (r), shows to be very important for DoA, with a positive correlation. At these mercerisation conditions, temperature shows no effect on DoA. The influence of the [NaOH] (which also refers to the concentration of water) shows a complex dependence on (r). As (r) increases and [NaOH] decreases, the measured DoA increases. Prolonged mercerisation time shows no significance in the modelled DoA. However, a gradual increase of the DoA over time was seen when mercerisation was performed with 30% and 40% [NaOH] at (r) = 0.8, suggesting a slow diffusion of NaOH and Na-Cell formation. 13C CP-MAS NMR measurements of samples produced at room temperature show that formation of the Na-Cell allomorph is mainly determined by the [NaOH]. However, in the transition area between Na-Cell I and Na-Cell II, (r) also seems to be of importance.  An increase of DS in the produced CMC samples also shows to be consistent at such conditions with the increase in the measured DoA and with increased (r) and decreased [NaOH]. However, these conditions also favour the formation of by-products. In the synthesised CMC samples, a DS of up to 0.7 was achieved. Measured solubility was lower than expected for any given DS. This, along with the non-statistical distribution of monomer units in the polymer chains, indicates high heterogeneity in the synthesised samples. The distribution of substituents within the AGU shows attachment to hydroxyl oxygens in the order O3 < O2 ≈ O6. The relative importance of the substitution at O3 indicates an increase at this position when [NaOH] increases.

The models presented in this thesis will hopefully serve as a basis for predicting the effects of the studied variables on the DoA, as well as on the mass yield of cellulose pulp when mercerisation conditions are adjusted. Moreover, it is believed that the presented studies can give a better understanding of mercerisation at cellulose ether conditions, hence enabling further development of this process step.

sted, utgiver, år, opplag, sider
Umeå: Umeå universitet, 2018. s. 81
Emneord
Mercerisation, Alkalinisation, Cellulose I, Cellulose II, Alkali cellulose, Viscose, Cellulose ether, Carboxymethylcellulose, Sodium glycolate, Sodium diglycolate, Raman spectroscopy
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-153412 (URN)978-91-7601-987-0 (ISBN)
Disputas
2018-12-14, KB.E3.01 (Lilla hörsalen), KBC-huset, Umeå, 10:00 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2018-11-23 Laget: 2018-11-19 Sist oppdatert: 2019-01-10bibliografisk kontrollert
Reyes, D. C., Gorzsas, A., Stridh, K., de Wit, P. & Sundman, O. (2017). Alkalization of dissolving cellulose pulp with highly concentrated caustic at low NaOH stoichiometric excess. Carbohydrate Polymers, 165, 213-220
Åpne denne publikasjonen i ny fane eller vindu >>Alkalization of dissolving cellulose pulp with highly concentrated caustic at low NaOH stoichiometric excess
Vise andre…
2017 (engelsk)Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 165, s. 213-220Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We present a quantitative study, using Raman spectroscopy combined with multivariate data analysis, to determine the degree of activation of softwood sulphite dissolving cellulose pulp by aqueous sodium hydroxide. We have chosen industrially relevant conditions, including low stoichiometric ratio of NaOH/Anhydroglucose Unit (AGU) <2 and highly concentrated caustic (>= 45% w/w [NaOH]). A design of experiments is used to investigate the effects of simultaneous variation of a set of key parameters on the degree of activation (i.e. transformation to alkali cellulose, denoted as DoA): (a) the NaOH/AGU stoichiometric ratio, denoted (r); (b) the concentration of NaOH, denoted [NaOH]; (c) temperature, denoted (T); and (d) reaction time, denoted (t). Solid-state C-13 CP/MAS NMR spectroscopy was applied to investigate the reproducibility of the experiments and to select the range for (t). According to the model, (r) is found to have a statistically significant effect on DoA (increasing from DoA= 6-30% at the lowest (r)=0.8, to DoA= 48-87% at the highest (r)=1.8), together with [NaOH]. The influence of [NaOH] depends strongly on (r). The other studied variables are found to be insignificant in the model and has a complicated influence on the activation. In particular, (T) is found to be unimportant in the studied range (30-60 degrees C), but increasing (t) from 5 to 25 min shows a positive influence on DoA, depending on both (r) and [NaOH]. A mercerisation mechanism that is controlled by diffusion is proposed to explain these phenomena. 

HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-134689 (URN)10.1016/j.carbpol.2017.02.045 (DOI)000399261900024 ()
Prosjekter
Bio4Energy
Tilgjengelig fra: 2017-06-22 Laget: 2017-06-22 Sist oppdatert: 2019-08-30bibliografisk kontrollert
Albán Reyes, D. C., Eliasson, B., Karlsson, L., de Wit, P., Svedberg, A. & Sundman, O. (2016). Activation of dissolving celluloses pulp for viscose and cellulose ether production. In: Ola Sundman (Ed.), The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives: . Paper presented at The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives, Örnsköldsvik, November 15-16, 2016 (pp. 29-30). Umeå ; Karlstad: Umeå university ; Karlstad university
Åpne denne publikasjonen i ny fane eller vindu >>Activation of dissolving celluloses pulp for viscose and cellulose ether production
Vise andre…
2016 (engelsk)Inngår i: The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives / [ed] Ola Sundman, Umeå ; Karlstad: Umeå university ; Karlstad university , 2016, s. 29-30Konferansepaper, Oral presentation with published abstract (Annet vitenskapelig)
Abstract [en]

Mercerisation of cellulose by alkali treatment is the most common procedure used to activate natural cellulose fibres into many commercial cellulosic materials. During mercerisation, the NaOH solution enters the cellulose fibres, transforming them into a swollen and a highly reactive material called alkali cellulose (Na-Cell). In case NaOH is completely washed out of the cellulose structure, Na-Cell turns into Cellulose II upon drying.

Traditionally the cellulose is mercerised by suspending it in a 15-20 % NaOH solution. The result is a high (15-25 mol/mol) NaOH: Anhydroglucose  molar ratio (r) and mercerisation in these conditions have been extensively studied. However, in modern production of cellulose ethers, the mercerisation conditions are often very different. The main reason is that any excess of water and OH--ions used during the mercerisation can later react with different chemicals in the process, thus forming unwanted by-products e.g. methanol. One way to avoid this kind of side reaction is by using low-water-content mercerisation conditions, i.e. low (r) = 0.8-1.8 mol/mol and high NaOH concentration (45-55% w/w). The traditional mercerisation is a suspension process while the cellulose during the latter process, i.e low-water-content mercerisation conditions, remains quite “dry”. Thus, although the chemical reaction principles of activation of cellulose for both viscose and cellulose ethers processes are the same, the activation conditions used are often very different. Therefore, the different dependencies of process parameters as well as any similarities between the processes are interesting.

The presentation summarises the findings presented in two papers which described the influence of the different parameters on the mercerisation/activation of softwood Sulphite dissolving pulp in viscose production conditions (Albán Reyes et al. 2016) and cellulose derivatives production conditions (Albán Reyes et al.) respectively. In the individual studies this has been done by analysing the degree of transformation (DoT) of dissolving pulp to Na-cellulose (or more correctly cellulose II after washing and upon drying) as a function of simultaneous variation of [NaOH], temperature, and reaction time varied using design of experiment. Also the (r) was varied for samples mercerised at dry conditions. A combination of Raman imaging and multivariate data analysis have been used to study the DoT to Cellulose II.

It was found that the mercerisation under the different conditions was dependent on different parameters. For traditional mercerisation, on the one hand, the temperature was shown to be important for the DoT and showed negative correlation with the data, while [NaOH] showed a positive correlation. On the other hand, at low-water-content mercerisation conditions the (r) was overall most important while the temperature showed no statistical importance in a Partial least squares analysis. Traditional mercerisation gave much higher DoT than the low-water-content mercerisation. Thus,  the data for low-water-content mercerisation was further examined at the different (r). The same chemistry is always expected and the different influences of the parameters seen is understood and discussed in terms of the different physical reaction mechanisms.  

sted, utgiver, år, opplag, sider
Umeå ; Karlstad: Umeå university ; Karlstad university, 2016
Emneord
cellulose, swelling, NaOH, cellulose ether production
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-128501 (URN)
Konferanse
The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives, Örnsköldsvik, November 15-16, 2016
Tilgjengelig fra: 2016-12-05 Laget: 2016-12-05 Sist oppdatert: 2019-01-08bibliografisk kontrollert
Albán Reyes, D. C., Skoglund, N., Svedberg, A., Eliasson, B. & Sundman, O. (2016). The influence of different parameters on the mercerisation of cellulose for viscose production. Cellulose (London), 23(2), 1061-1072
Åpne denne publikasjonen i ny fane eller vindu >>The influence of different parameters on the mercerisation of cellulose for viscose production
Vise andre…
2016 (engelsk)Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 2, s. 1061-1072Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

sted, utgiver, år, opplag, sider
Springer Netherlands, 2016
Emneord
Mercerisation, Cellulose I, Cellulose II, Raman spectroscopy, X-ray diffraction patterns, Multivariate data analysis
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-119633 (URN)10.1007/s10570-016-0879-0 (DOI)000373136400005 ()2-s2.0-84957694846 (Scopus ID)
Prosjekter
bio4Energy
Tilgjengelig fra: 2016-05-11 Laget: 2016-04-25 Sist oppdatert: 2020-01-13bibliografisk kontrollert
Albán Reyes, D. C., Sundman, O., Schröder, U., Karlsson, L., de Wit, P. & Eliasson, B. (2015). Activation of dissolving cellulose pulp at low water content. In: 4th EPNOE International Polysaccharide Conference: Polysaccharides and polysaccharide-based advance materials: from science to industry. Paper presented at 4th EPNOE International Polysaccharide Conference "Polysaccharides and polysaccharide-based advance materials: from science to industry". 2015, Warsaw, Poland.
Åpne denne publikasjonen i ny fane eller vindu >>Activation of dissolving cellulose pulp at low water content
Vise andre…
2015 (engelsk)Inngår i: 4th EPNOE International Polysaccharide Conference: Polysaccharides and polysaccharide-based advance materials: from science to industry, 2015Konferansepaper, Poster (with or without abstract) (Annet vitenskapelig)
Abstract [en]

Mercerisation of cellulose by alkali treatment is the first step in modifying natural cellulose fibres into many commercial cellulosic materials. During treatment, the fiber transforms into a reactive and highly swollen material called alkali cellulose (Na-Cell). In case NaOH is washed out of the cellulose structure, Na-Cell turn into Cellulose II upon drying (Langan et al. 2001).

 

The aim of the present study was to gain a better understanding of the mercerisation of dissolving cellulose pulp at low water content. This has been done by spraying NaOH onto milled cellulose in a kneader, then washing the cellulose to neutrality to stop the reaction. After drying the transformation degree to cellulose II was analysed. The experiments include variation of temperature (30-60°C), reaction time (5 and 25 min), [NaOH] (45-55%), and NaOH:Cellulose molar ratio (0.8- 1.8). A combination of NIR Raman imaging and multivariate data analysis have been used to study the transformation degree.

 

To the authors’ knowledge, this is the first time the influence of NaOH: Cellulose molar ratio on the mercerisation process has been studied in a single model together with temperature, reaction time and [NaOH]. Our results indicate that increased NaOH: Cellulose molar ratio has a significant positive influence on transformation degree of dissolving cellulose pulp at low water content.

Emneord
cellulose ethers, mercerisation
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-128509 (URN)
Konferanse
4th EPNOE International Polysaccharide Conference "Polysaccharides and polysaccharide-based advance materials: from science to industry". 2015, Warsaw, Poland
Tilgjengelig fra: 2016-12-06 Laget: 2016-12-06 Sist oppdatert: 2019-02-28bibliografisk kontrollert
Albán Reyes, D. C., de Wit, P. P. & Sundman, O.Variation of the alkalisation conditions during the synthesis of a cellulose ether.
Åpne denne publikasjonen i ny fane eller vindu >>Variation of the alkalisation conditions during the synthesis of a cellulose ether
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
Abstract [en]

We show the effect of simultaneous variation of i) the NaOH/AGU (anhydroglucose unit) stoichiometric ratio (r), ii) added [NaOH], and iii) mercerization time, on the degree of cellulose substitution (DS), and by-product formation including proportions of insoluble particles and unreacted chemicals, in the synthesis of carboxymethylcellulose (CMC), under conditions resembling those often used for production of non-ionic cellulose ethers and without the use of alcohols. The DS was found to increase when (r) was increased (range 1.0-1.3) and added [NaOH] was decreased (range 50-30%). However, such changes also favoured the formation of unwanted by-products. Decreased (r) and increased [NaOH] resulted in increased the quantities of insoluble particles and unreacted chemicals. In the CMC samples, DS of 0.18-0.7 was obtained. The measured solubility (46%-86%) was lower than expected for a given DS. This, along with a deviation of the substituent distribution from the statistical calculations, indicated a high heterogeneity in the samples. The substitution at hydroxyl positions within the AGU shows the order of < ≈ , and that substitution increases with (r). The relative importance of substitution at increases with an increased [NaOH].

Emneord
Mercerisation, Alkalinisation, Cellulose Ethers, Carboxymethylcellulose, Sodium glycolate, Sodium diglycolate
HSV kategori
Identifikatorer
urn:nbn:se:umu:diva-153349 (URN)
Tilgjengelig fra: 2018-11-16 Laget: 2018-11-16 Sist oppdatert: 2018-11-20
Organisasjoner