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The Effect of Chemical and Biopulping Process on Bagasse Pulp.

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Dev. Chem. Eng. Mineral Process. 13(5/6),pp. 639-644, 2005.
The Effect of Chemical and Biopulping
Process on Bagasse Pulp
Antares& Y. Sudaryanto, Setiyadi, H. Wibowo, Yogi,
and Y. Purnomo
Department of Chemical Engineering, Widya Mandala Catholic
University,Jl. Kalijudan 3 7, Surabaya 60114, Indonesia
The amount of sugarcane bagasse in Indonesia is abundant while the utilization is
still limited. One of the alternatives f i r bagasse utilization is as pulp material. To
minimize the waste from the pulping process, the effect of using a chemical process
(with nitric acid) and a biopulping process (using Fusarium solani) were studied and
measured by the percentage of a-cellulose content in bagasse pulp. In the chemical
process, the nitric acid concentration and the reaction time were varied. llre pulping
process was conducted at constant temperature of 102°C and the mixture was
agitated at 900 rpm. The highest percentage of a-cellulose content in pulp was
79.28%, obtained at the concentration of 3.5% for a reaction time of 3.5 hours. At
higher concentrations and longer cooking times, the a-cellulose decreased due to the
cellulose degradation. In the biopulping process, the incubation temperature was kept
at 30°C. The highestpercentage of a-cellulose was 65.80% obtained at an incubation
time of 25 days. When compared to nitric acid pulping, biopulping is less eflcient.
However it has one advantage that it only uses a small amount of chemicals and,
therefore, creates less pollutants.
Introduction
In Indonesia, the amount of bagasse in the waste from a sugarcane factory is
abundant. However, the utilization of bagasse is still limited. One of the alternatives
to be explored is using bagasse as a non-wood-pulp raw material. As the amount of
paper production is increasing, this alternative is advantageous because it helps to
slow deforestation caused by the h g h demand for wood pulp.
In the paper industry, pulping is the first processing step. The pulping process
aims to remove as much lignin as possible, and avoid the decomposition of cellulose
during the process. Cellulose is a linear polymer with glucose as repeating unit, while
* Author for correspondence (resti@mail.wima.ac.id).
639
Antaresti, Y. Sudatyanto, Setiyadi, H. Wibowo, Yogi and Y.Purnomo
lignin is a polymer with irregular patterns of the repeating unit. Unlike cellulose,
which has an aliphatic structure, lignin has an aromatic structure. The hydrogen
bonding in cellulose determines the strength of the paper produced. In plants, lignh
binds the cellulose and hemicellulose and to remove lignin usually requires the use of
strong chemicals. These conditions lead to the decomposition of cellulose, which
affects the paper strength.
There are various pulping processes that have been used in industry. The most
common process is chemical pulping using sulfate which is known as Kraft pulping.
This process has many advantages compared to other processes but the waste is
difficult to treat. To solve this problem, it is necessary to find an efficient and
environmentally friendly pulping process.
Much research has been conducted using various chemicals to replace sulfate
pulping. One of them uses nitric acid, which is actually an old method. A study using
nitric acid for grass pulping showed that the waste liquor can be used as fertilizer
[Agra and Warnijati, 19741. Nitric acid process is also often mentioned as an ideal
process for small-scale pulp production, but the process efficiency should be further
improved so that it can be more competitive [Leslie and Kyrklund, 19801.
A recent method which is gaining more attention uses microorganisms, commonly
fungi, for the pulping process. This process is known as biopulping. In the biopulping
process, the fungi which will be used should have a lignin-degrading enzyme. There
are many kind of enzymes which are involved in the lignin degradation process such
as manganese peroxidase, lignin peroxidase and laccasse.
Many studies showed that white rot h g i can be used for biopulping, but it is still
not feasible for application on an industrial scale due to the long processing time. To
shorten the processing time it is important to find a strain which has better capability
in selectively degrading lignin. FIIsarium solani, which has been studied for toxic
organic chemical degradation, also secreted extracellular enzyme which can degrade
lignin [Rodriquez et al., 19961. Based on their study, F. solani has the prospect to be
applied in biopulping.
In our research, the efficiencies of chemical pulping using nitric acid and
biopulping using F. solani as applied to bagasse were compared. The efficiency was
measured in terms of the percentage of a-cellulose content, which is an important
element of pulp that will influence the strength of the paper produced. In the nitric
acid process, the concentration and reaction time were varied to obtain an optimum
result. The concentrations of nitric acid used were from 2.5% to 8.5%, while the
reaction time was varied from 1.5 hours to 3.5 hours. While in the biopulping process,
the incubation period was varied from 5 to 25 days.
Materials Used and Experimental Methods
(i) Materials
The bagasse used in this work was supplied by Candi Sugarcane Factory, Sidoarjo
and Gempolkerep Sugarcane Factory, Mojokerto. It was sun-dried, shredded and
sieved to size of 40 mesh before it was processed. The chemicals used were analysis
reagent grade. F. solani was obtained from the Faculty of Mathematics and Science,
Airlangga University, Surabaya, Indonesia.
645
The Effect of Chemical and Biopulping Process on Bagasse Pulp
(ii) Methods
Nitric acid pulping process
Nitric acid solution was poured into a three-necked flask which was equipped with a
condenser, thermometer and agitator. The solution was heated and after the
temperature reached approx. 102"C, a measured amount of bagasse was poured into
the flask. During the process, the temperature was kept at 102°C and agitation rate at
900 rpm. The concentrations of nitric acid were varied from 2.5% to 8.5%, while the
reaction time was varied from 1.5 hours to 3.5 hours. After the reaction was
completed, the liquor was filtered. The cake was mixed with 2% sodium hydroxide
and heated at 70°C for 5 minutes to remove the degraded lignin. Pulp was separated
fiom the liquor by filtration. The percentage of a-cellulose content was analyzed
based on the weight of dried pulp.
Biopulping
Culture media consisting of NaN03 (2 g), KlHP04 (1 g), MgS04 (0.5 g), KC1 (0.5 g),
FeS04 (0.01 g), sucrose (10 g). were dissolved in 1 liter of distilled water. A
measured amount of bagasse was added into the liquid media and sterilized for the
starter inoculum media. F. solani was inoculated into the media and incubated for 5
to 7 days at 30°C. After the starter was ready, it was poured into a 300 ml flask which
contained sterilized bagasse and incubated for 5 to 25 days at room temperature of
approx. 30°C. During incubation the flask was sealed. The liquor was removed from
the pulp by filtration. The cake was mixed with 2% sodium hydroxide and heated at
70°C for 5 minutes to remove the degraded lignin. The percentage of a-cellulose
content was again analyzed based on the weight of dned pulp.
Results and Discussion
(i) Nitric acid pulping
The effect of nitric acid pulping on the percentage of a-cellulose content in bagasse
pulp can be seen in Figure 1, the percentage of a-cellulose content in pulp increases
as the reaction time increases. As the nitric acid concentration increases from 2.5% to
3.5%, the a-cellulose content increases but at higher concentration the a-cellulose
content starts to decrease. The hlghest percentage of a-cellulose content was 79.28%
obtained at the concentration of 3.5% for reaction time of 3.5 hours.
In the pulping process in order to get a higher a-cellulose content, the lignin must
be removed from the raw material. Nitric acid can hydrolyze both lignin and
cellulose. As the reaction proceeds to longer times, the amount of lignin which is
broken down by nitric acid will increase. The nitrated lignin is partially water soluble
and therefore alkali treatment is necessary after the pulping process. However, the
increase of a-cellulose is becoming less significant as the reaction time approached
3 hours since most of the lignin has been removed.
64I
Antaresti, Y. Sudaryanto, Setiyadi, H. Wibowo, Yogi and Y. Purnomo
79.5
79
-5
h
s
-+1.5 hour
78.5
Y
8
-3
0
-t2.0 hour
78
2.5 hour
-*
3.0 hour
0
5 77.5
I
m
77
76.5
I
0
1
2
3
4
5
6
7
8
9
HN03Concentration (%)
Figure 1. Percentage of a-cellulose content in bagasse pulp by nitric acid pulping.
n
v
g
70
65
60
55
3 50
;45
2a 40
= 35
0
? 30
a 25
0
I
5
10
15
20
25
Incubation time ( days )
I
Figure 2. Percentage of a-cellulose content in bagasse pulp by biopulping.
642
30
The Effect of Chemical and Biopulping Process on Bagasse Pulp
The concentration of nitric acid influences the reactivity during the pulping
process. At a particular concentration and reaction time, nitric acid only removed
lignin. When the concentration is increased, nitric acid becomes more reactive and it
will remove lignin at faster rate. After the l i p is removed, nitric acid will attack the
cellulose, then the a-cellulose content will decrease because it is hydrolyzed into its
monomer, glucose.
(ii) Biopulping
The percentage of a-cellulose content in bagasse pulp by biopulping using F. solani
was influenced by the incubation time as shown in Figure 2. In the biopulping
process, F. solani produces extracellular lignolytic enzyme which can degrade lignin.
As the incubation time increases, F. soluni will grow and multiply. With higher
numbers of microorganism, the amount of lignolytic enzyme produced will also
accumulate. Therefore, the amount of lignin degraded will increase and result in a
higher percentage of a-cellulose content in pulp.
After the incubation time reached 20 days, the percentage of a-cellulose content
was nearly constant. Th~smay be due to several factors. At an incubation of 20 days,
the lignin might have been removed completely, thus after 20 days the increase of
a-cellulose content in pulp was not significant. Another factor is that the oxygen in
the incubation flask may be almost exhausted. Most of the lignin degradation
mechanism by microorganism is an enzymatic oxidative reaction which needs oxygen
[Breen and Singleton, 19991. If the oxygen concentration is limited, then the
degradation reaction will be disturbed. In addition to the limited oxygen, some
microorganism may have entered the death phase. At an incubation time of 25 days,
the percentage a-cellulose content in pulp reached a maximum of 65.80%.
Compared to nitric acid pulping, the percentage of a-cellulose content in pulp
obtained from biopulping using F. soluni is lower and the process takes longer time.
In the biopulping process, the fungi actually does not use lignin as their major carbon
source. They only degrade lignin in order to obtain cellulose which is a more valuable
carbon source for the fungi. The removal of lignin and degradation of cellulose into
its monomer, glucose, may occur simultaneously. Therefore, the percentage
a-cellulose content in pulp can not be as high as for chemical pulping.
Conclusions
For chemical pulping using nitric acid having concentration of 2.5% to 8.5% and
reaction time of 1.5 hours to 3.5 hours, the lughest percentage of a-cellulose content
in bagasse pulp was 79.28% (obtained at 3.5% concentration and 3.5 hours reaction
time). The percentage of a-cellulose content in bagasse pulp by biopulping using F.
solani was lower than for the nitric acid pulping. The highest percentage of
a-cellulose content for an incubation time of 5 to 25 days was 65.80% obtained after
25 days. However, even though the percentage of a-cellulose content obtained was
lower, biopulping produces less pollutants because it only uses a small amount of
chemicals.
643
Antaresti, Y. Sudaryanto, Setiyadi, H. Wibowo, Yogi and Y.Purnomo
References
1. Agra, I.B., and Wamijati, S. 1974. Pulp dari Alang-alang dengan Proses Asam Nitrat dan Proses Soda,
Forum Teknik, 4(2). 80-85 (in Indonesian).
2. Breen, A., and Singleton, F.L. 1999. Fungi in Lignocellulose Breakdown and Biopulping, Current
Opinions in Biotechnology, 10, 252-258.
3. Hatakka, A. 2001. Biodegradation ofLignin, In Eiopolynrer, Steinbuchel, A., and Hofrichter, M.(eds);
Volume 1, Wiley-VCH, Weinheim.pp.129-167.
4. Leslie, A.J., and Kyrklund, B. 1980. Small-scale Mills/or Developing Countries, Unasylva, 32, 128130.
5. Patt, R., and Kordsachia, 0. 1991. Paper and Pulp, In Ullman's Encyclopedia of Industrial Chemistry,
5& ed., Vol. A18, pp.547-593, VCH Publisher, New York.
6. Rodriquez, A., et al. 1996. Degradation of Natural Lignins and Lignocellulosic Substrates by Soilinhabiting Fungi Imperfecti,FEMS Microbiology Ecology, 21. 213-21.
644
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