2011 - Europe Direct Iasi

R.22.
Title
Authors
Institution
Description
R.23.
EUROINVENT 2011
new substances.
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allows us to draw conclusions about the mode of action of
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Environmentally friendly pulping and bleaching of
agricultural residues
Tofanica B.M., Puitel A.C., Gavrilescu D.
"Gheorghe Asachi" Technical University of Iasi
Faculty of Chemical Engineering and Environmental
Protection, Natural and Synthetic Polymers Department
The aim of this study is to investigate the possibilities of
producing chemical pulp with low residual lignin content from
rapeseed stalks by means of conventional sulphur-free pulping
followed by oxygen delignification. Chemical pulping was
carried out by soda-anthraquinone method under varying
conditions. The influence of sodium hydroxide as active alkali
(16, 18, 20 and 22% on oven dried stalks) and maximum
temperature (150°C, 160°C, 170°C) on the cellulose yield, lignin
content and intrinsic viscosity was studied. Time to achieve
maximum temperature (60 minutes), reaction time at maximum
temperature (60 minutes), solid-to-liquid ratio (1:5) and addition
of 0.5% anthraquinone (o.d.) to the alkaline liquor were kept
constant in all experiments. Although using severe cooking
conditions caused reduction of yield and Kappa number, desired
delignification was achieved with addition of 18% of NaOH on
oven dried raw material at 170°C cooking temperature. The
results indicated that active alkali was the most important
parameter, temperature having a minor effect on pulp yield and
residual lignin content. Rapeseed pulp showed cellulosic fibers
yields of 37-48% with Kappa number in range 28-111. Pulps
with lower Kappa numbers (28, 35 and 57) were further
subjected to a bleaching stage, showing that rapeseed pulp was
easily delignified by oxygen delignification to a low Kappa
number (14, 20 and 35) without any significant loss in viscosity.
It was also noted that cellulosic fibers possess similar levels of
delignification and yields as compared to those made from our
earlier study on conventional sulphate pulping of rapeseed stalk.
Innovative Researches
149