TY - JOUR
T1 - Alkalization of dissolving cellulose pulp with highly concentrated caustic at low NaOH stoichiometric excess
AU - Albán Reyes, Diana Carolina
AU - Gorzsás, András
AU - Stridh, Kjell
AU - de Wit, Paul
AU - Sundman, Ola
PY - 2017/6/1
Y1 - 2017/6/1
N2 - 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 13C 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 °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.
AB - 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 13C 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 °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.
KW - Alkalinisation
KW - Cellulose ether
KW - Cellulose I
KW - Cellulose II
KW - Mercerisation
KW - Raman spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85013156223&partnerID=8YFLogxK
U2 - 10.1016/j.carbpol.2017.02.045
DO - 10.1016/j.carbpol.2017.02.045
M3 - Article
C2 - 28363542
AN - SCOPUS:85013156223
VL - 165
SP - 213
EP - 220
JO - Carbohydrate Polymers
JF - Carbohydrate Polymers
SN - 0144-8617
ER -