The Effect of Delignification Time on % Yield of Alpha-cellulose

from Bamboo Fiber (Bambuseae) Properties

Julika Sitinjak

, Halimatuddahliana Nasution

and Maulida Lubis

Department of Chemical Engineering, Universitas Sumatera Utara, Padang Bulan, Medan, Indonesia

Keywords: Alpha-cellulose, Bamboo Fiber, Biocomposite, Biopolymer.

Abstract: Bamboo fiber (Bambuseae) has cellulose content that can be used as a filler in the composites. The

objective of this study is to obtain alpha cellulose from bamboo fiber, through the isolation process. This

study was carried out using the delignification method with NaOH solvent on temperature at 80

C and the

time variations of 30, 60, 90, 120, 180 minutes as the first stage of separation of alpha cellulose from other

compounds contained in bamboo fiber. The results showed that the optimum condition of delignification

time was 60 minutes with yield of 55.26%. The FTIR spectra was performed to confirm the formation of the

product (alpha cellulose) proved by spectrum indicating the presence of the cellulose compound

characterized by peak formation in 1641 cm

-1

absorption area by comparing the cluster on the reaction alpha

cellulose with the cluster on the bamboo fiber. XRD result showed that the crystalline portion of alpha

cellulose was higher than amorf portion of alpha cellulose itself with the total amount of crystallinity index

was 93.3%.

1 INTRODUCTION

Bamboo is a plant of tropical and subtropical

regions. Naturally, bamboo can growth in primer

forest and also in secunder forest (former farm and

grower). Bamboo is classified as a non-timber forest

product, which is known by the community as a

versatile plant. It is said like that because this plant

can be used for various purposes, one of the benefits

is as an alternative to wood. Bamboo is easily

obtained at a relatively cheap price and the

production age is relatively fast. Bamboo is included

in natural fibers where natural fibers that can be

directly obtained from nature. The amount of

cellulose in fiber varies according to the source and

it is usually related to materials such as water, wax,

pectin, protein, lignin and mineral substances.

As a source of fiber, bamboo has a cellulose

content of 60.8% and lignin 32.2% with mechanical

strength ranging from 140-800 MPa (Liu et al.,

2012). The high potential of bamboo causes bamboo

fibers can be processed and developed into products

with high economic value, one of them as a

reinforcement in the composite. One of the

cellulosic content is alpha-cellulose which has a high

glossy fiber tensile strength and settles on a

concentration of 17.5% NaOH solution.

Cellulosecan be differentiated based on the degree of

polymerization (DP) and solubility in the 17.5%

sodium hydroxide compound (Klemm et al., 1998).

Figure 1 and 2 show the cellulose and alpha-

cellulosestructures.

Figure 1: Cellulose Structure (Nuringtyas, 2010).

Figure 2: Alpha Cellulose Structure (Nuringtyas, 2010).

The previous research on the effect of

delignification time on % yield alpha cellulose

derived fromkepok banana peel showed the

optimum condition was at 2 hours with yields of

190

Sitinjak, J., Nasution, H. and Lubis, M.

The Effect of Deligniﬁcation Time on % Yield of Alpha-cellulose from Bamboo Fiber (Bambuseae) Properties.

DOI: 10.5220/0010138500002775

In Proceedings of the 1st International MIPAnet Conference on Science and Mathematics (IMC-SciMath 2019), pages 190-195

ISBN: 978-989-758-556-2

23.72% (Yannasandy et al., 2017). Moreover, klutuk

banana stems (Musa Balbisiana Colla) showed the

best % yield of alpha cellulose was 28.77%

(Zulaekha et al., 2018)and the green coconut showed

(Cocos Nucifera L.) the best % yield of alpha

cellulose was 30.01% (Damanik et al., 2016).

The method that used to isolate alpha cellulose is

the method of deposition of alpha cellulose with

17.5% NaOH solution by heating it in a magnetic

stirred heater (Putri & Gea, 2018). In this study we

tried to examine the effect of cooking time on %

yield alpha cellulose from bamboo fiber.

2 METHODS

2.1 Materials

The chemicals that used in this study were aquadest,

HNO

, NaNO

, NaOH, Na

, NaOCl, NaOH, and

which obtained as received. Bamboo fiber

obtained from residential housing in Deli Serdang,

North Sumatera.

2.2 Preparation of Fiber from Bamboo

Bamboo was cut into small pieces and washed with

water then curled under the sun for 2 hours. The

dried bamboo was mashed with a grinder to get 90

mesh. Fiber was carried out in three stages of the

chemical process, namely delignification,

alkalization, and bleaching to produce alpha

cellulose.

2.3 Isolation Alpha Cellulose

2.3.1 Delignification Process

Delignification processaims to remove lignin which

contained in the fiber.The bamboo fiber was

weighed 75g and then put into a beaker. It was

added 3.5% HNO

and 10 mg NaNO

and stirring for

120 minutes at90

2.3.2 Alkaline Process

The alkalization process aims to remove impurities

which contained in the fiber. Alkalization process

consist of alkalization process I and II. Alkalization

process I added 2% NaOH and Na

2% stirring

for 60 minutes with temperature 50

C. Alkalization

process II added 17.5% NaOH and stirring for30

minutes at 80

2.3.3 Bleaching Process

The bleaching stage aims to remove the remaining

lignin from the alkali. Bleaching process consists of

bleaching process I and II. Bleaching process I used

1.75% of NaOCl with stirring process for20 minutes

at 60

C. The bleaching process II used 10% of H

with stirring process for60 minutes at 60

2.4 Yield Calculation

The alpha cellulose results in the form of residual

residue on boiling flask are then dried by using an

oven at 80

C for 1 hour. Weighing the weight of the

fiber. Weighing the weight of the residue after

extraction. Yields Percentage is calculated using

equation (1).

𝑌𝑖𝑒𝑙𝑑











𝑥 100 % (1)

2.5 Lignin Content using Klason

Method

The delignification time was made by using 17.5%

of NaOH solution above the hot plate at 80

C with

variables of time are 30, 60, 90, 120, 180 minutes.

The delignification process by the klason method

aims to separate alpha cellulose from lignin.

Chemicals added during the delignification process

are expected to reduce % lignin.

Alpha cellulose was weighed 2g for samples (B)

were put 500 ml glass beaker for alpha cellulose and

then soaked in water that has been given ice for 20

minutes, then added 72% H

as much as 40 ml

for alpha cellulose, stirred slowly while stirring for 2

hours then 400 ml of aquadest for alpha cellulose

into 2000 ml for alpha cellulose. 1540 ml of water

added for alpha cellulose. So the concentration of

sulfuric acid becomes 3%. Then the solution is

heated to boiling and left on a water bath for 4 hours

with low heat. Allow the sample to stand until the

lignin deposits settle completely. Then filtered with

filter paper in a beaker glass that has been known the

weight. The lignin wash deposits until acid free with

hot water (test with litmus). The filter paper are

dried in oven at 105

C for 3 hours, cooled in a

desiccator and weighed to a constant weight

(A).Calculation of lignin content can be calculated

with the equation below.

Calculation of Lignin Content:

𝑋











𝑥 100 % (2)

Information:

The Effect of Deligniﬁcation Time on % Yield of Alpha-cellulose from Bamboo Fiber (Bambuseae) Properties

191

X = Value of lignin content,(%)

A = Weight of lignin precipitate, (g)

B = Weight of dry sample, (g).

2.6 Characterization of X-ray

Diffraction (XRD) Analysis

The determination of the crystallinity index of

cellulose material can be calculated through the

segal method, with the equation below.

Segal method:

𝐶𝑟𝑙  













 (3)

Information:

002

= The maximum intensity of the 002 diffraction

pattern which is a representation of the two

zones, namely the crystal zone and amorphous

zone.

= The intensity of the diffraction in the same

unit which is a representation of the amorphous

zone.

2.7 Characterization of Fourier

Transform Infrared (FTIR)

Analysis

FTIR testing is carried out to determine the chemical

bonds of alpha cellulose fibers at chemical

treatment. The FTIR specification is Nicolet iS10

FT-IR Spectometer Instrument.

3 RESULT AND DISCUSSION

3.1 Effect of Delignification Time on

the % Yield of Alpha Cellulose

The analysis was used to know the % yield of alpha

cellulose obtained from bamboo fiber. The lignin

content in bamboo fiber is 24.88%. Table 1 shows

the effect of delignification time on the % yield of

alpha cellulose and remaining of % lignin.

Table 1: Effect of Delignification Time on The %Yield of

Alpha Cellulose and Remaining of %Lignin.

Delignification

time

% Yield of

Alpha Cellulose

% Lignin

30 49.56 1.65

60 55.26 1.62

90 50.54 1.58

120 48.41 1.55

180 46.17 1.45

From the table above, it can be seen that in

general there is an increase in the % yield of 30

minutes to 60 minutes, but there is a decrease for 90

minutes. The % yield value at 30 minutes is 49.56%,

increased to 55.26%, and decreased at 90 minutes to

50.54%. The increasing of the delignification time

will affect the delignification process. Where an

increase in delignification time will cause more

dissolved lignin and the impregnation process

between the solvent and alpha cellulose is more

perfect (Sjostrom, 1995).

However, at the time of delignification that is

long enough will trigger the degradation of alpha

cellulose compounds that cause a decrease in the

yield obtained (Daud et al., 2007). From the table

above, it can be seen that the longer the

delignification time, the lower of the lignin content.

This proves that the longer delignification time will

affect the level of lignin obtained (Jalaluddin &

Rizal, 2005).

The decreased percentage of lignin inside alpha

cellulose is affected by temperature. Lignin will

dissolve at high temperatures in the black leachate

because the hydroxyl phenolate lignin group is in an

ionized state to form its salt and. This treatment will

break lignin into smaller particles (Ariani &

Idiawati, 2011).

Lignin levels decrease with the addition of

NaOH. The addition of an alkaline base in the form

of NaOH will make it easier to break the bonds of

lignin compounds. Figure 3 show reaction of

lingocellulose bonds breaking using NaOH.

Figure 3: Reaction of Lignocellulose Bonds Breaking

Using NaOH (Fengel & Wegener, 1989).

NaOH molecules will enter the lignocelluloses

and break down the structure of lignin (Elwin et al.,

2013). So that lignin is more soluble which results in

decreased levels of lignin.

3.2 Results and Discussion of X-ray

Diffraction (XRD) Analysis

The more orderly arrangement of atoms in a material

is directly proportional to the higher level of

IMC-SciMath 2019 - The International MIPAnet Conference on Science and Mathematics (IMC-SciMath)

192

crystallinity. The determination of crystallinity of

alpha cellulose was carried out by the X-ray

Diffraction (XRD) method based on the amorphous

crystal diffraction spectrum pattern. The results of

the crystallinity test using XRD can be seen in

Figure 4 below.

Figure 4: Alpha Cellulose XRD Spectrum Results from

Alpha Cellulose.

The crystallinity index of alpha cellulose for

bamboo fiber was calculated using the Segal

method. The peak absorption of the spectra

produced by alpha cellulose samples from bamboo

fibers is at 2θ = 22° and I

at 2θ = 16° indicating

the crystalline portion of cellulose. From the peak of

the absorption can be determined the crystallinity

index of alpha cellulose.

From the Segal method, the crystallinity index of

alpha cellulose for bamboo fiber is equal to 93.3%, it

indicated by the sharp peak absorption (sharp peak)

of the spectrum produced in the alpha cellulose for

bamboo fiber samples. High crystallinity shows that

the arrangement of the polymer chains in the

material is arranged regularly or the crystalline

portion is more perfect (Lu & Hsieh, 2010). This

increase in crystallinity is caused by a decrease in

the amorphous fiber composition due to chemical

treatment. Chemical treatment is directed at

removing hemicellulose, lignin, pectin, which are

fiber components that contribute to the amorphous

part of the fiber (Susheel et al., 2009).

The amorphous part is more easily hydrolyzed

compared to the crystalline part, so the hydrolysis

treatment causes the fibers to become more

crystalline (Elanthikkal et al., 2010). Alpha cellulose

for bamboo fibers obtained has a high crystallinity

index where the crystallinity index of alpha cellulose

is usually in the range of 55-80% (Zeinali et al.,

2014).

3.3 Results and Discussion of Fourier

Transform Infrared (FTIR)

Analysis

Bamboo fiber has components, namely lignin,

hemicellulose and cellulose. The three components

are composed of alkanes, esters, aromatics and

alcohol (Gian et al., 2017). The characterization of

Fourier Transform Infra Red (FTIR) is to identify

the functional groups that exist in the alpha cellulose

and compared with bamboo fiber as raw material for

alpha cellulose. The characterization of FTIR and

functional group absorbance regions of alpha

cellulose and bamboo fiber fillers can be seen in

Figure 5 and Table 2 below:

Figure 5: FTIR Spectrums of (a) Bamboo Fiber(b) Alpha

Cellulose Bamboo Fiber.

Table 2: TheAbsorption peak of Bamboo and Alpha

Cellulose Bamboo Fiber.

Bond Type

Wave Number (cm

-1

)

Bamboo

Fiber(cm

-1

)

Alpha Cellulose

Bamboo

Fiber(cm

-1

)

O-H Stretching 3331 3334

C-H Stretching 2891 2905

C-HDeformation 1602 1641

C=C 1241 1225

C-O 1031 1024

The figure above shows the absorption peak of

bamboo and alpha cellulose bamboo fibers. In the

process of alkalization reduced the hydrogen bonds

due to the removal of hydroxyl groups by reacting

with sodium hydroxide. The results of the

alkalization process showed the concentration of the

-OH stretching group. The wave frequency of 3350-

The Effect of Deligniﬁcation Time on % Yield of Alpha-cellulose from Bamboo Fiber (Bambuseae) Properties

193

3175 cm

-1

indicates the presence of OH bonds

(Zhbankov, 1966).

As seen in bamboo fibers with an absorption

peak of 3346 cm

-1

whereas in alpha cellulose

bamboo fibers showed an area of absorption that

was sharper at 3341 cm

-1

. It indicates that the O-H

bond was stretching due to the influence of

alkalization. Alkalization reduces hydrogen bonds

because the hydroxyl group reacts with sodium

hydroxide which causes an increase in the

concentration of -OH when compared to bamboo

fibers (Łojewska et al., 2005).

Furthermore, wave frequencies from 3000-

2850cm

-1

indicates the presence of CH stretching

groups (Zhbankov, 1966). Bamboo fibers are shown

in the absorption area of 2891cm

-1

and in alpha

cellulose bamboo fibers appear sharper absorption

area at 2905 cm

-1

. The absorption peak shows the

stretching of the C-H aliphatic group where the

residual hemicellulose from the delignification

process and the structural changes of the C-H bond

cause the peak to shift toward the maximum

(Zhbankov, 1966).

Concentration of -CH

deformation bonds was

shown in bamboo fibers with an absorption area of

1602cm

-1

. Whereas the alpha cellulose bamboo fiber

looks sharper with the absorption area of 1641 cm

-1

It shows the crystalline area, where the absorption

area will increase along with the purification process

(Alves et al., 2014)

The double bond C=C of aromatic compounds is

shown to have a peak at susceptible 1200-1300 cm

-1

The uptake of the 1241cm

-1

area in the bamboo fiber

looks sharper compared to the alpha cellulose

bamboo fiber in the absorption area of 1225cm

-1

. In

the aromatic group C=C, it can be seen that lignin is

still present, which means that the alkaline treatment

has not completely eliminated lignin but only

reduced the level of lignin (Han, 2015).

In the picture above it can also be seen that there

are concentrations of C-O groups in the absorption

area between 1000-1200cm

-1

. In bamboo fiber, it can

be seen that the absorption peaks appear sharper at

1031cm

-1

, whereas in alpha cellulose bamboo fibers

have absorption peaks at 1024cm

-1

. Both samples are

thought to originate from the vibration of the

pyronose ring group on the cellulose unit (1035–

1170cm

-1

referring to the pyronose ring) where the

absorption peak indicates enrichment of cellulose

fibers and it can be proven that the sharp peak

absorption of the C-O group contained in the alpha

cellulose of bamboo fiber further indicate the

presence of a pyronese ring which is a typical group

that only belongs to the cellulose unit and is not

owned by the lignin and hemicellulose components

(Peng et al., 2011).

4 CONCLUSION

Alpha cellulose had been obtained succesfully from

bamboo fibers by using sodium hydroxide (NaOH)

solvent. It was revealed that the longer the

delignification time, the higher of the yield of alpha

cellulose up to 60 minutes. However, the longer

delignification time up to 180 minutes, the lower of

the yield of alpha cellulose. It was caused by the

degradation of alpha cellulose to glucose molecules.

FTIR showed that alpha cellulose from bamboo

fibers have the similar structure with cellulose

structure. XRD result showed that the crystalline

portion of alpha cellulose was higher than amorf

portion of alpha cellulose itself with the total amount

of crystallinity index was 93.3%.

ACKNOWLEDGEMENT

The authors gratefully acknowledge that the research

was supported by Department of Chemical

Engineering, Faculty of Engineering, Universitas

Sumatera Utara in facilitating this research.

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