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Agave sisalana has very short basal stems, usually less than 0.5 m tall. Mature plants have relatively large green or greyish-green leaves usually 90-130 cm long that are usually very rigid. These leaves do
not have any prickles along their margins [11]. Meanwhile, A. angustifolia has light green leaves, short
leaves, great number of leaves, sharp and closed thorny leaves in the edge. A. angustifolia has very short
basal stems, usually less than 0.5 m tall. Mature plants have relatively small light green, grayish-green or variegated leaves usually 30-60 cm long that are usually very rigid. These leaves have numerous
small prickles 2-5 mm long along their margins. This species produces large capsules and sometimes also develops numerous plantlets i.e. bulbils on the branches of its lower clusters [11].
Table 1. Qualitative Charachters of Agave germplasm in Balittas.
Collection name
Agave type Leaves color
Margin of leaves color
Prickle of leaves margin
Color of tip spine
Balittas 1 A.angustifolia
Green Light green
Notched, big prickly Dark-brown
Balittas 4 A.angustifolia
Green Light green
Notched, big prickly Dark- brown
Balittas 5 A.angustifolia
Green Light green
Notched, big prickly Dark- brown
Balittas 9 A.angustifolia
Green Light green
Notched, big prickly Dark- brown
Balittas 19 A.angustifolia
Green Yellowish green
Notched, big prickly Dark- brown
Balittas 2 A.cantala
Dark green Dark green
Notched, big prickly Dark- brown
Balittas 3 A.cantala
Dark green Dark green
Notched, big prickly Dark- brown
Balittas 6 A.Cantala
Dark green Dark green
Notched, big prickly Dark- brown
Balittas 7 A.Cantala
Dark green Dark green
Notched, big prickly Dark- brown
Balittas 8 A.Cantala
Dark green Dark green
Notched, big prickly Dark- brown
Balittas 11 A.Cantala
Dark green Dark green
Notched, big prickly Dark- brown
Balittas 15 A.Cantala
Greyish-green Green
Notched, big prickly Dark- brown
Balittas 20 A.Cantala
Grey Yellowish green
Notched, big prickly Dark- brown
Balittas 21 A.Cantala
Grey Green
Notched, big prickly Dark- brown
Balittas 22 A.Cantala
Grey Grey
Notched, big prickly Dark- brown
Balittas 26 A.Cantala
Grey Green
Straight, big prickly Dark- brown
Balittas 10 A.Sisalana
Dark green Dark green
Rare, straight prickly Dark- brown
Balittas 12 A.Sisalana
Dark green Yellow
Straight, Small prickly Dark- brown
Balittas 13 A.Sisalana
Dark green Yellow
Straight, Small prickly Dark- brown
Balittas 14 A.Sisalana
Green Light green
Notched, big prickly Dark- brown
Balittas 16 A.Sisalana
Grey Grey
Without prickly Dark- brown
Balittas 24 A.Sisalana
Grey Grey
Without prickly Dark- brown
Balittas 25 A.Sisalana
Grey Green
Without prickly Dark- brown
b. The Growth, Growth Rate and Fiber Content of Agave Germplasm
At age 3 years the average height and length of A. cantala leaves were, respectively 1.68 m and 1.18 m, while the average height and length of A. sisalana leaves were 1.41 m and 0.97 m respectively.
Meanwhile Agave angustifolia has average height of 106.41 cm and average length of leaves of 82.8 cm.
For the length of leaves, A. sisalana has 10.46 cm that is wider than A. cantala which is 9.43 cm and also A. angustifolia which is 7.79 cm. According to [12] stating that Agave americana until the lowering
phase, the height of Agave plant can reach of 2.4 - 7.6 m with the length of leaves reaches of 1.8 m. in the agave sisala, the height of plant until the lowering phase can reach of 7- 9 m, with the length of leaves
reaches 1.5 m [5]. In agave angustifolia, the height of plant ranges from 70 to 90 cm, with mature leaf length ranging from 110 to 130 cm and width from 8 to 10 cm [13].
The number of A. angustifolia leaves reaches 77.18 sheets per year. This shows greater number
than A. sisalana 49.77 and A. cantala 53.94. Brown mentioned that during the life until before the
lowering phase, the agave can produce 220 sheets of leaves per planting process. The research result by
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[12] showed that in Agave Americana, the growth of number of leaves each year can reach 40-50 sheets.
Based on the data in Table 2, it shows that until the fourth year, the height of plant, length of leaves and width of leaves are still lower than the growth of agave plant in other countries.
The coeficient value of agave germplasm in Balittas of for the characters of height of plant, length and width of leaves show the diversity less than 50 . The diversity of genetic of agave germplasm
in Balittas is categorized as medium. This is based on the grouping on the diversity coeficient value conducted by [14]. The coeficient of genetic diversity is classiied into 4 criteria, namely: coeficient
value of 0 - 25 is categorized as low coeficient value, 25 - 50 is medium coeficient value. The coeficient value of 50 - 75 is categorized as high coeficient value and coeficient value more than
75 is categorized as the highest coeficient value. The
Agave germplasm in 2015 has been in the second year of production. The irst harvesting is conducted when the plant has been in the second year. The harvest is conducted for the leaves that have
been old and formed angle of 45
o
C with the length is not less than 1 meter [15]. Meanwhile, [12] made a limitation that the harvest of agave leaves is conducted after the plant is three years old. The harvest of
agave leaves is conducted twice in a year, namely in May and November. The harvest of agave can be conducted until the plant is in lowering phase. The agave plant can produce until it reaches the age of
8-30 years old [12]. Leaves can be harvested after two years of age, which will postpone the “bolting” for 15-20 years. After “bolting”, the plant dies.
Based on Table 2. It shows that the growth rate of agave germplasm of Balittas collection keeps increasing. The greatest increase of
Agave angustifoliais in accession Balittas 9 and the lowest one is in accession Balittas 1. The growth rate of
Agave angustifolia germplasm height of collection Balittas is 61.45 – 107.41 cm for 3 years. The average number of leaves reaches of 29.08 – 56.33 sheets for 3 years.
The average of lenght of leaves reaches of 30.79 - 65.53 cm. Meanwhile, the average growth of width of leaves reaches of 2.66 - 4.73 cm for 3 years.
Table 2. The Growth rate and iber content of Agave germplasm
NamaAksesi Plant height
cm Leave number
sheet Lenght of
leaves cm Width of
leaves cm Fibers
content Agave
angustifolia Balittas 1
61.45 29.08
30.79 2.66
2.95 Balittas 4
77.43 29.67
57.83 3.80
2.82 Balittas 5
106.42 39.00
63.29 4.73
2.32 Balittas 9
107.41 40.17
63.10 4.65
2.50 Balittas 19
82.15 56.33
65.53 4.41
3.81 Agave cantala Balittas 2
114.95 34.34
48.68 3.40
3.64 Balittas 3
138.00 24.50
46.45 5.19
3.99 Balittas 6
106.77 29.42
73.48 4.2
2.93 Balittas 7
110.23 39.92
75.00 4.68
4.13 Balittas 8
118.04 37.17
69.27 4.28
3.50 Balittas 11
137.40 25.50
43.70 6.17
3.76 Balittas 20
141.78 33.09
58.07 6.14
3.51 Balittas 21
150.70 54.75
60.19 6.48
3.55 Balittas 22
141.06 36.75
43.84 6.25
4.59 Balittas 26
93.86 29.50
81.21 4.75
4.42 Agave
sisalana Balittas 10
100.25 34.17
25.25 6.75
2.77 Balittas 12
145.89 37.33
56.38 8.33
2.66 Balittas 13
98.00 29.52
87.75 5.20
2.79 Balittas 14
131.29 38.08
74.75 9.20
2.95 Balittas 15
157.34 31.84
61.12 7.48
3.36 Balittas 16
60.96 21.42
28.88 2.88
2.95 Balittas 25
74.91 8.59
51.05 2.82
3.07 Rerata
110.80 35.65
59.04 5.41
3.26 KK
20.90 14.42
5.64 12.01
20.30
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The greatest growth rate of Agave cantala is in accession Balittas 21 and the lowest one is in accession
Balittas 26. The growth of Agave cantala germplasm height of Balittas collection is 93.86 - 150.70 cm
for 3 years. The average growth of number of leaves reaches of 24.50 – 54.75 sheets for 3 years. The average growth of lenght of leaves reaches of 43.84 – 81.21 cm. Meanwhile, the average growth of
width of leaves reaches of 3.40 – 6.48 cm for 3 years. Meanwhile, the greatest growth rate of Agave
sisalana is in accession Balittas 15 and the smallest one is in accession Balittas 16. The growth of Agave
cantala germplas height of Balittas collection is 60.96 – 157.34 cm for 3 years. The average growth of number of leaves reaches of 8.59 – 38.08 sheets for 3 years. The average growth of length of leaves
reaches of 25.25 – 87.75 cm. Meanwhile, the average growth of width of leaves reaches of 2.82 – 9.20 cm for 3 years. In general, it shows the normal growth of morphology characters from the three types of
agave, namely
Agave angustifolia, Agave cantala and Agave sisalana. The growth of Agave germplas is more determined by each genetic. The growth of
Agave angustifolia tends to be slower than Agave sisalana and
Agave cantala. The greatest average of
A. angustifolia iber level is 3.81 , the greatest average of A. cantala iber level is 4.59 and the greatest average of A. sisalana
iber level is 3.36 . According to [12] stated that the agave iber level can reach of 4-5. The lenght of leaves, the number of leaves, the width of
leaves and weight of leaves are an important determinant of result component for iber producer plants from the leaves. The length of leaves, number of leaves, and weight of leaves have positive correlation
on the agave iber results. Meanwhile, according to [16] there was a signiicant interaction between the characters of number of leaves, lenght of leaves, results of dried iber and all parameters of iber quality
in the environment.
Conclusion
Based on the morphology characters of agave germplasm collection in Balittas, it can be divided into 3 types, namely agave angustifolia, agave cantala and agave sisalana. Based on the plant morphology
characters, it shows that the agave cantala has greater characters of height of plant and lenght of leaves than sisalana or agave angustifolia. Meanwhile, for the character of number of leaves, the greatest is in
agave angustifolia. The agave sisalana has most signiicant character in its width of leaves. The growth of agave cantalagermplasm shows it has faster growth than sisalana or angustifolia. A. Cantala has the
highest value of production component than other agave types.
References
1. Santoso B. Peluang Pengembangan Agave Sebagai Sumber Serat Alam. Perspektif 2009; 8.2: 84 – 95.
2. Nu~nez, HM. Biofuel Potential in Mexico: Land Use, Economic and Environmental E_ects Work-in-Progress. Department of Economics Centro de Investigaci_on y Docencia Econ_omicas
Aguascalientes, Mexico. Agricultural and Applied Economics Association Annual Meeting. Boston, Massachusetts. 2016.
3. Almaraz AN, Amanda EDA, Antonio JÁR, Natividad JUS, Silvia LGV. The Phenols of the Genus Agave Agavaceae. Journal of Biomaterials and Nanobiotechnology 2013; 4: 9-16.
4. Monterrosas BN. Martha LAO, Enrique JF, Antonio RJA, Zamilpa A, Manases GC, Jaime T, and Maribel HR. Anti-Inlammatory Activity of Different Agave Plants and the Compound
Cantalasaponin-1. Molecules 2013;18: 8136-8146. 5. Tewari DYC, Tripathi and Anjum N.
Agave sislana: a plant with high chemical diversity and medicinal importance. Pharmaceutical Research 2014; 3. 8: 238-249
6. Budiman I, Aulya FS, Subyakto, Subiyanto B, Laporan akhir tahun, UPT BPP Biomaterial LIPI, Penelitian pemanfaatan serat sisal Agave sisalana untuk pembuatan komposit serat semen:
hubungan antara temperatur hidrasi dengan kuat tekan. UPT Balai Penelitian dan Pengembangan Biomaterial LIPI. 2006.
7. Subyakto, Hermiati E, Heri DYY, Fitria. Proses pembuatan serat selulosa berukuran nanodari sisal Agave sisalana dan bamboo betung Dendrocalamusasper. Beritaselulosa 2009; 44.2: 57- 65.
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8. Kusumastuti A, Aplikasi Serat Sisal sebagai Komposit Polimer. .J.KompetensiTeknik 2009; 1.1:
27-32. 9. Zimmermann T, Pohler E, Geiger T. Cellulose Fibrils for Polymer Reinforcement. Advanced
Engineering Science 2004; 6.9: 754-761 10. Gajatri SB, Status Pengelolaan Plasma Nutfah Jagung.
Plasma Nutfah 2007;13. 1: 11-18. 11. Anonymous, Weeds of Australia - Biosecurity Queensland Edition Fact Sheet. Agave sisalanahttp:
www . keyserver.lucidcentral.orgweedsdata...agave_sisalana.pdf. 2016.
12. Hulle A, Kadole P, and Katkar P. Review Agave Americana Leaf Fibers. Fibers 2015; 3: 64-75.
13. Hidalgo MR, Magdaleno CC, Luis HHG and Guillermo UC, 2015. Chemical and morphological characterization of
agave angustifolia bagasse ibers. Botanical sciences 2015; 93. 4: 807-817. 14. Rebin RW. and DS Decker W. Cucurbits. Central for Agricultural and Bioscience International.
USA. 1995. 15. Brown K. Agave sisalana Perrine. University of Florida, Center for Aquatic and Invasive Plants,
7922 N.W. 71st Street, Gainesville, FL 32653; www.se eppc.org...pdfsummer2002-brown- pp18-21.pdf
diaksestanggal 9 September 2016. 16. La-Vina HC.
Stability of Yield and iber ineness in ramiBoehmerianivea[L.]Gaud.http:agris.fao. orgagrissearchsearchdisplay.do? F=1994 2FPH2FPH94008.xml3BPH9410635. Diakses 20
Mei 2016.
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IMPROVED OXYGEN DELIGNIFICATION BY PHOTO PRETREATMENT AND ADDITIVE REINFORCEMENT:
A COMPARISON STUDY BETWEEN TROPICAL MIXED HARDWOOD KRAFT PULP AND OIL PALM FIBRE SODA-ANTHRAQUINONE PULP
Leh Cheu Peng
a1
, Chong Yin Hui, Wan Rosli Wan Daud, Mazlan Ibrahim and Poh Beng Teik
a
Bioresource, Paper and Coatings Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang
1
cplehusm.my
ABSTRACT
Oxygen deligniication O is an important process in pulp and paper industry for enhanced elemental chlorine-free EFC or totally chlorine-free TCF bleaching. The application of an O could remove the
residual lignin from unbleached pulp up to 50 percent and therefore, reduce the burden to the bleaching plant. The major drawback of O is its relatively lower selectivity between deligniication and cellulose
degradation in comparison to other bleaching agent. For attaining a more eficient chlorine-free ECF or TCF bleaching, as the irst bleaching stage, the selectivity of the O has to be improved. In this
study, the selectivity of O was improved through three different modiication approaches—additive reinforcement, pre-treatment and the combination of the two modiications toward two different pulps
namely tropical mixed hardwood kraft pulp and oil palm empty fruit bunch EFB soda-anthraquinone pulp. The results obtained showed that all the modiication approaches were capable of improving the
bleaching selectivity up to 90 by retaining higher pulp viscosity and achieving better kappa number reduction. The simple photo pretreatment could even eliminate the hexenuronic acid more than 60.
These indicated that the beneicial effects of improved Os were repeatable on the two different pulps. Keywords: anthraquinone; bleaching selectivity; hexenuronic acid; oxygen deligniication; photo
pretreatment
Introduction
Among all the chlorine-free bleaching agents, oxygen deligniication O is commonly used as the irst bleaching stage to eliminate residual lignin in bulk from the brown stock. However, in comparison
to conventional chlorination C bleaching, O shows relatively lower selectivity in between delignifying power and carbohydrates degradation, and the deligniication is generally limited to no more than
50 to prevent unwarranted carbohydrates degradation[1-2]. As a result, chlorine-free bleached pulps commonly show relatively lower strength properties as well as pulp brightness [3-4]. Hence, the
improvement of O is very important as it may alleviate the number of bleaching stage required to avoid undesired degradation of cellulose and increase the brightness of pulp as well.
Over the past thirty years, many attempts have been made to improve the selectivity of the O with minor modiications such as additional of additives or implementation of a pre-treatment prior to the
process. In 2010, Ng and co-worker 2010 were recommended a higher H
2
O
2
charge 0.5 and small amount of anthraquinone AQ added in the O on oil palm empty fruit bunch EFB soda-AQ pulp. The
results of study have proven that the addition of H
2
O
2
and AQ during O generally gives a satisfactory acceleration on the pulp brightness and minimizes cellulose deterioration while retain a rather high
degree of deligniication [5-6]. Nevertheless, there is no further modiied O’s research carried out or continued on different chemical pulps even thought the capability of the O
pAQ
bleaching process is remarkable.
On the other hand, some researchers have also found that photo pretreatment can increase the bleaching selectivity due to the generation of reactive radicals during the treatment and they may degrade the lignin
into smaller molecules [5-7] and thus, increase the deligniication eficiency in the subsequent bleaching stage. In this study, the improved O by both additive reinforcement and photo pretreatment, and also
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the combination of two approaches were applied on two different chemical pulps viz. mixed tropical hardwood kraft pulp and oil palm empty fruit bunch EFB soda-anthraquinone pulp. The effectiveness
of the three modiication approaches on the two chemical pulps were compared based on pulp properties such as kappa number, viscosity, selectivity, hexenuronic acid content and pulp brightness.
Experimental Materials
Sabah Forest Industries Sdn. Bhd, Sabah, Malaysia provided the mixed tropical hardwood brown kraft pulp with kappa number of 16.4, pulp viscosity of 30.4 cP, and 36 ISO brightness. The oil palm
empty fruit brunch EFB was provided by by Eco Fibre Bhd., Johor, Malaysia. The EFB was soaked in water for one day and washed, in order to remove contaminants such as sand, dust and oil, then it was
air-dried and kept in plastic bags prior to pulping.
Soda-Anthraquinone Pulp Preparation
Pulping of EFB was carried out in a 6 L stainless steel digester. Four hundred gram of oven-dried o.d. EFB was cooked at 160
o
C with 25 of sodium hydroxide and 0.1 anthraquinone on the oven dry basic of EFB, material-to-liquor ratio of 1:7, time-to-temperature of 90 min and time-at-temperature of
120 min. After the completion of cooking, the collected EFB soda-AQ pulp was deiberized in a hydro- pulper for 10 min and washed thoroughly with tap water in a stainless steel mesh ilter. The pulp was
further disintegrated mechanically in a three bladed disintegrator for 1 minute at a pulp consistency of 2.0 and then screened by Somerville lat-plate screen with 0.15mm slits. The pulp was then spin-dried
and kept in the fridge 4
o
C before used.
Methods Photo Pretreatment
Twenty ive grams of hardwood kraft pulp was soaked in the acid solution with pH 5 adjusted by adding 0.5M sulphuric acid solution for 15 min. The pulp stock was then squeezed to remove excess
acid solution to reach 10 consistency. After that, the pulp sample was transferred into a polyethylene bag and photo irradiation was carried by placing the pulp sample under ultraviolet, 369 nm 6 watt for
a desired duration of time. The distance between the lamp and pulp sample was 3 cm for blue light and 5 cm for the UV light. After the completion, the pulp was washed and spins dried, and then continued
with oxygen deligniication.
Improved Oxygen Deligniication O with Hydrogen Peroxide O
p
and Anthraquinone O
pAQ
Oxygen deligniication O was carried out using a 650-mL stainless steel autoclave equipped with a gas inlet and stirrer, manufactured by the Parr Instrument Company, USA. Twenty-two gram oven-
dry basis of pulp sample was mixed with 0.5 magnesium sulfate and 2.5 sodium hydroxide and distilled water was added to adjust the pulp consistency to 10. After the cover was fastened, the air
in the autoclave was replaced by oxygen gas through a gas inlet, and the pressure inside the autoclave
was kept at 0.55 MPa and 95°C for 30 min. At the end of the deligniication process, the autoclave was cooled and the oxygen pressure was released. The pulp was then washed, spin-dried, and analyzed.
The procedures of the improved O, viz. hydrogen peroxide reinforced O O
p
and anthraquinone AQ aided hydrogen peroxide-reinforced O O
pAQ
were same as the O, additional hydrogen peroxide and AQ were added according to the amount shown in Table 1. All the chemicals used above were
based on oven-dry basis of pulp sample.
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Table 1. Amount of reinforced additives added to oxygen deligniication.
Type of raw material Type of improved O
H
2
O
2
, Anthraquinone,
SFI hardwood kraft pulp O
p
1.4 -
O
pAQ
1.4 0.04
EFB soda-AQ pulp O
p
1.2 -
O
pAQ
1.2 0.02
Pulp Properties
The deligniied pulp was analyzed by the Technical Association of the Pulp and Paper Industry TAPPI T236 2013 to ind the kappa number, TAPPI T230 2008 to establish pulp viscosity, ISO2470
2008 to determine pulp brightness, and TAPPI T282 2013 to determine hexenuronic acid content of the chemical pulp. Bleaching selectivity is deined as the relative reactivity of a bleaching process
toward the lignin and carbohydrate components of pulp and it was calculated as the ratio between the difference in kappa number to the difference in pulp viscosity cP before and after the process [5,6].
Analysis of Residual Lignin and Deligniied Pulp by FTIR Absorption Spectroscopy
FTIR spectral data were obtained using the potassium bromide KBr pellet technique. Infrared spectra were recorded using a Shimadzu FTIR spectrometer, model 8201PC Japan. Small amounts of
sample pulp or lignin were mixed with the KBr powder at a concentration of 1 mg100 mg KBr. The mixture was then ground for 3 to 5 min. The powder was pressed for 2 min to form a KBr pellet. The
collar was placed with the pellet onto the sample holder. The spectra were recorded in the absorption
band of 4000 to 400 cm−1.
Result and Discussion
The results demonstrated in Table 1 demonstrated that the kappa number K
n
reduction of both the hardwood kraft and EFB Soda-AQ pulps by O was not quite impressive, which was limited to not more
than 38 and 30 Figure 1, respectively. Hence, it would substantially limit the role of O as the irst bleaching stage in the chlorine-free bleaching sequence. Therefore, to improve the bleaching selectivity
of the O, some modiication such as additional of additives or implementation of a pretreatment prior to the deligniication process were carried out. Fig. 1 shows that bleachability of the EFB pulps by O was
higher than that of hardwood kraft pulp with the selectivity of 0.63 and 0.53, respectively, even though the latter showed higher kappa number K
n
reduction Figure 1, it experienced more severe drop in pulp viscosity Table 1.
Improved Oxygen Deligniication by Additive Reinforcement
As shown in Table 2 and Figure 1, it is quite notably that the additional of hydrogen peroxide into an O, known as H
2
O
2
reinforced O O
p
, offered a greater improvement on deligniication and brightening effects for both chemical pulps, in which the K
n
reduction and ISO brightness of hardwood pulp was increased to 55.6 and 52, while those of EFB pulp were increased to 42.1 and 66.8, respectively.
The addition of H
2
O
2
in an O causes the generation of more reactive species such as hydropeoxide anion HO
2
-, hydroxyl radical OH· and superoxide anion radical O
2
·
-
due to the decomposition of H
2
O
2
[2,5]. Since the generated radicals react actively with organic compounds, they would degrade the residual lignin in the pulp and at the same time destroy the chromophoric structures in lignin. As a result,
it increased both the kappa number reduction and pulp brightness. However, since the radical reactive species generated in the system attacked both lignin and carbohydrates unselectively, the cellulose
degradation was accelerated as well [2,5-7]. Nevertheless, in comparison to deligniication, the effect of
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hydrogen peroxide on cellulose degradation was relatively smaller, and thus, ended up that the bleaching selectivity of the hardwood kraft and EFB pulps was improved to 0.71 and 0.74, respectively Figure 2.
Table 2. Bleaching conditions of oxygen and improved oxygen deligniication
Pretreatment Stage
Deligniication Stage
Responses 360nm UV
Exposure time, min
Type of Oxygen Deligniication
Kappa Number
Pulp Viscosity
cP Brightness
ISO, Hexenuronic
acid, μmolg
SFI Hardwood Unbleached pulp 16.4±0.4
30.4±0.3 36.0±1.8
55.5±2.3 -
O 10.2±0.2
18.7±0.1 43.2±1.5
49.3±3.1 -
O
p
-stage 7.3±0.5
17.5±0.5 52.0±1.8
52.6±5.7 -
O
pAQ
-stage 8.4±0.2
20.4±0.2 52.6±1.8
46.2±6.3 30
O 7.6±0.1
21.7±0.4 47.8±2.3
24.8±2.9 30
O
p
-stage 6.7
±0.2 17.1±0.5
60.3±0.9 20.4±3.1
30 O
pAQ
-stage 7.2±0.5
18.3±0.2 50.9±1.2
28.0±2.0 EFB Soda-AQ Unbleached pulp
11.1±0.3 18.8±0.4
47.5±0.6 47.2±2.3
- O
7.8±0.4 13.6±0.5
55.3±1.2 42.9±3.2
- O
p
-stage 6.4±0.2
12.5±0.3 66.8±1.1
40.7±3.9 -
O
pAQ
-stage 7.2±0.3
14.2±0.4 65.6±0.9
41.3±4.3 30
O 6.9±0.1
15.1±0.5 56.9±1.3
20.9±4.6 30
O
p
-stage 5.9±0.3
13.1±0.4 67.0±0.5
18.9±3.6 30
O
pAQ
-stage 6.3±0.2
14.6±0.3 65.1±0.7
22.6±3.3
On the other hand, the addition of an optimum amount of anthraquinone AQ in an O
p
, named as AQ- aided H
2
O
2
reinforced O O
pAQ
, was capable of preserving the cellulose from degradation. As shown in Table 2, the pulp viscosities of both hardwood and EFB pulps were retained even higher than that of
the ordinary O one. Different from O
p
, which its selectivity was increased mainly due to the extended deligniication, the O
pAQ
improved the bleaching selectivity through both carbohydrate stabilization and extended deligniication. Nevertheless, in comparison to O
p
, the K
n
reduction of O
pAQ
was lesser.
Fig. 1. Kappa number reduction of oxygen deligniied pulps with and without modiication According to previous studies, when AQ was added in an alkaline bleaching system, it would reduce
to anthrahydroquinone AHQ through oxidizing cellulose reducing end groups to alkali-stale aldonic acid groups. Since AHQ was readily being oxidized by strong oxidants such as hydroxyl radicals, thus,
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the AQ added in the bleaching system acted as a hydroxyl radical scavenger [5-6,8-9] and therefore might diminish the happening of cellulose degradation caused by hydroxyl radical. However, at the same time
the deligniication due to radical attack was also moderated. Even so, there was no signiicant effect of AQ on the pulp brightness as the O
pAQ
bleached hardwood and EFB pulps remained the same brightness as O
p
bleached pulped. On the other hand, improved O by O
p
and O
pAQ
did not show signiicant effect on the reduction of the hexenuronic acid HexA content for both the pulps used in this study. This indicated
that the addition of the additives hydrogen peroxide and AQ in the O did not help in reducing the HexA content. By comparing the hardwood pulp and EFB pulp, it was found that O
pAQ
gave better improvement on bleaching selectivity to the former 37.7 than the latter 23.8. Nevertheless, due to the initial
properties of the unbleached pulp, the EFB Soda-AQ pulp achieved lower K
n
and higher ISO brightness.
Improved Oxygen Deligniication by Photo Pretreatment
The application of UV photo pretreatment for only 30 min prior to O on both chemical pulps showed positive effects on deligniication and pulp viscosity preservation. As shown in Table 2, the K
n
of both hardwood and EFB pulps was reduced to 7.6 and 6.9, hence the K
n
reduction was enhanced to 57.3 and 37.8 Figure 1, respectively. On the other hand, it was very surprise to see that the increase of
deligniication by the photo pretreatment not only did not cause more serious cellulose degradation, it even diminished cellulose degradation during the subsequent O and thus, enhanced the bleaching
selectivity of the hardwood and EFB pulps to 1.01 and 1.14 Figure 2, respectively, which accounted to 90 and 80 improvement on selectivity.
Moreover, photo pretreatment also showed an overwhelming effect of on eliminating HexA from pulp. The Ph-O was capable of removing more than 55 of HexA from both the unbleached pulps,
which was much more effective than the ordinary O or even improved Os Op and O
pAQ
. As reported by many researchers, HexA groups could be only hydrolysed under drastic acidic condition and which
was strongly inluenced by reaction temperature and pH [13,14]. However, in this study, a simple photo pretreatment in mild acidic medium pH5 for 30 min without heating process could easily remove the
HexA more than 50. It was believed that the unsaturated double bonds in the HexA could absorb the energyproton released from the irradiation process and subsequently initiated the hydrolysis of the
HexA [15,16]. Nevertheless, the Ph-O pulp showed merely a small improvement on pulp brightness in comparison to the O as there was no additional brightening agent such as H
2
O
2
added. Based on the results of the two chemical pulps, it was found that the UV photo-pre-treatment was
applicable on different pulps and gave the similar effect as well. Nevertheless, the augmentation of selectivity of EFB pulp was better than that of hardwood pulp. On the other hand, the enhancement of
K
n
reduction of latter was much greater than that of the former. This was possibly due the initial K
n
of unbleached EFB pulp was rather low and might contain lesser phenolic groups, which are easier to be
attacked under alkaline O, it its residual lignin. Fig. 2. Selectivity of oxygen deligniication with and without modiication.
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Improved Oxygen Deligniication by Combination of Photo Pretreatment and Additives Reinforcement
Both the additive reinforced O and photo-pre-treatment O were capable of improving the bleaching selectivity of the two chemical pulps with different approaches. Furthermore the former enhanced the
brightness increment while the latter increased the removal of HexA. However, based on the results in Table 2, the combination of both approaches offered merely slightly increase in K
n
reduction but there was no further improvement on the bleaching selectivity. This indicated that single modiication of O
might have achieved the asymptotical limit of deligniication, therefore, the extended deligniication become least feasible. Nevertheless, the resultant pulp bleached by combination approaches attained
the beneits of higher pulp brightness and low in HexA content, which were never achieved at once by applying only single approach neither via additive reinforcement nor photo pretreatment.
Based on selectivity, the combination modiication of O was more workable for EFB pulp than hardwood pulp, wherein the selectivity of the EFB Ph-O
p
and Ph-O
pAQ
was still retained considerably high whereas the selectivity of both the hardwood bleached by combination approaches was lower than
that of single approach.
Conclusion
The modiications of oxygen deligniication O by additives reinforcement and pre-treatment were successfully improved the performance of O in all aspects—kappa number reduction, pulp viscosity
preservation, brightness increment and removal of hexenuronic acid. Additive reinforcement gave better effect on brightness increment whilst the photo pretreatment enhanced the cellulose stability and removal
of hexenuronic acid. In comparison to single approach, modiication of O by combination approaches attained the beneits of both higher pulp brightness and lower in HexA content. The effect of improved
O on the hardwood pulp and EFB pulps was basically in similar trend. Based on the improvement of selectivity, the photo-pretreatment and combination modiication of O was more workable for EFB pulp
than hardwood pulp
Acknowledgment
The authors would like to acknowledge the inancial support from grants funded by Universiti Sains Malaysia [FRGS Grant 203-PTEKIND6711327] and USM fellowships scheme and scholarship
sponsored by the Ministry of Higher Education MOHE Malaysia Mybrain15 MyPhD to Miss Chong Yin Hui.
References
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Chem Res 2001; 40:5680-5685
2. Suchy M and Argyropoulos DS. Catalysis and activation of oxygen and peroxide deligniication of
chemical pulps: A review.
TAPPI J 2002; 7854:2-43
3. Ismail D and Guniz G. Dimensionless parameter approach for oxygen deligniication kinetics. Ind
Eng Chem Res 2008; 4716: 5871–5878
4. Leh CP, Wan Rosli WD, Zainuddin Z and Tanaka R Optimization of oxygen deligniication in
production of totally chlorine-free cellulose pulps from oil palm empty fruit bunch ibre. Ind Crop
Prod 2008; 28:260-267
5. Ng SH, Ghazali A, and Leh CP. Anthraquinone-aided hydrogen peroxide reinforced oxygen deligniication of oil palm Elaeis guineensis EFB pulp: A two-level factorial design. Cell Chem
Technol 2011; 451-2:77-87
6. Chong YH, Ng SH, and Leh CP. Improved oxygen deligniication selectivity of oil palm EFB Soda-
AQ pulp: Effect of photo pre-treatment and AQ-aided H
2
O
2
reinforcement. Cell Chem Technol
2013; 473-4:277-283
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7. Sun YP, Kien Loi NY and Wallis AFA. Totally chlorine-free TCF bleaching of radiata pine kraft pulp involving a UV-peroxide stage.
APPITA J 1996; 49:96-99
8. Liu Z, Cao Y, Yao H, and Wu S. Oxygen deligniication of wheat straw soda pulp with anthraquinone
addition.
BioResources 2013; 81:1306-1319
9. Dence CW and Reeve DW. Pulp Bleaching: Principles and Practice. Atlanta, GA: Tappi Press;
1996, pp. 213-239. 10. Hon DNS. Photochemical degradation of lignocellulosic materials. In Grassie, N. Ed. Developments
in Polymer Degradation-3. London: Applied Science Ltd; 1983, p 229-281 11. Bikova T and Treimanis A. UV-absorbance of oxidized xylan and monocarboxyl cellulose in alkaline
solutions.
Carbohyd Polym 2004; 553: 315-322
12. Sjöström E. Wood chemistry: Fundamentals and applications. San Diego: Academic Press Inc; 1993
13. Jiang ZH, Audet A, Sullivan J, Lierop BV and Berry R. A new method for quantifying hexenuronic acid groups in chemical pulps.
Pulp Pap Sci 2001; 273:92-97
14. Vuorinen T, Burchet J, Teleman A and Fagerstrom P. Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of krafts pulps.
Pulp Pap Sci 1997; 255:155-162
15. Sixta H and Rutkowska EW. Comprehensive kinetic study on kraft pulping of Eucalyptus Globulus Part 2.
O Papel 2007; 682: 68-81.
16. Bajpai P. Environmentally Benign Approaches for Pulp Bleaching. Amsterdam, The Netherlands:
Elsevier, 1st Edition; 2005
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GREEN TECHNOLOGY IN THE PULP INDUSTRY
Dominique Lachenal
1
, Christine Chirat
Grenoble INP-Pagora BP 65, 38402 Saint Martin d’Hères Cedex France,
1
dominique.lachenalgrenoble-inp.fr
ABSTRACT
Kraft cooking and ECF bleaching has become the universal way of producing cellulose pulp ibers from wood. These processes have been so well optimized that impressive progresses have been made
in the last decades in reducing the environmental impact of pulp manufacture. However there is still some matter of improvement. Two on-going new developments are presented in this paper. The irst
one concerns the conversion of pulping process into a bioreinery operation in which prehydrolysis is performed prior to cooking. Such an approach is already an industrial reality for the production
of dissolving pulp. In a near future the prehydrolysis iltrate will be recovered since it represents an important source of hemicellulosic sugars. The main point discussed here is that after prehydrolysis,
cooking is much easier. Among the likely reasons are the lower occurrence of lignin carbohydrate linkages, the cleavage of some ether bonds and the better accessibility of the lignin. The change in
kinetics is such that the kraft cook could be replaced by a soda cook. In an optimum situation the caustic
soda cook is stopped at higher kappa number and is continued by an extensive oxygen deligniication. Using a sulfur free caustic soda cook in place of a kraft cook represents a major process simpliication
and a move toward greener technology. The second development deals with the implementation of green bleaching for chemical pulps. Because the common bleaching process uses chlorine dioxide, it
remains the cause of signiicant water consumption, release of organic materials in the aqueous efluent and formation of hazardous chlorinated compounds. Replacing chlorine dioxide by ozone is a most
straightforward means to develop an environmentally friendly bleaching process. Ozone offers many advantages compared to chlorine dioxide: it is a more powerful oxidant, it produces a chloride-free
efluent that can be recovered and burnt. Ozone-based totally chlorine-free sequences are proposed which do not affect pulp quality and are economically attractive. These improvements have been made
possible thanks to close examination of the chemistry of ozone with pulp components. It is thought that pulping and bleaching operations will necessarily evolve in a near future because a green product such
as cellulose deserves to be produced by the best available technologies.
Keywords: sulphur-free cooking; caustic soda cooking; prehydrolysis; totally chlorine-free bleaching; ozone
Introduction
The kraft process has become the universal way of producing cellulose for paper making. The reason is the unbeatable quality of the extracted cellulose ibres and the overall eficiency of the process which
allows for the production of cellulose from wood without any consumption of the cooking chemicals which are entirely recovered, and with a marginal use of fossil fuel, the energy needed being provided by
the combustion of the cooking liquor which contains around 50 of the original weight of the processed wood. The energy balance is so favourable that the kraft pulp mills are net producers of energy under
the form of green electricity. No other process so far has met such records. However, despite its global performance, the kraft process suffers from several drawbacks:
• more than 50 of the wood components lignin and most of the hemicelluloses are burned, which is not the most valuable usage of these sophisticated macromolecules.
• methylmercaptan and dimethyl sulphide are released in the atmosphere. Although they do not present any toxicity, their smell is spoiling the environment of a kraft pulp mill over dozens of kilometres.
Progress has been made to capture these gases at their point of emission, but the odour problem can only be eficiently tackled in new kraft pulp mills.
• bleaching of the kraft cellulosic ibres still uses chlorinated organic chemicals mainly chlorine
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dioxide. This practice not only generates potentially toxic chlorinated chemicals but also prevents the combustion of the bleaching efluent because it contains chloride ions. As a result, bleaching is
by far the main contributor to the water pollution of a kraft pulp mill.
This paper summarizes the research efforts which address these problems and will contribute to the development of a sustainable cellulose industry.
The Kraft Bioreinery Concept
Converting a kraft pulp mill to a bioreinery represents the most realistic mean to develop a sustainable production of chemicals from lignocellulosic biomass. In theory, many other processes may be used to
this purpose. They are not described here. For many reasons, it makes more sense and is technically and economically more attractive to take proit of existing cellulose production mills to develop such
a chemical platform. The challenges are then to extract the hemicelluloses prior to the deligniication and to recover some of the lignin dissolved in the cooking liquor, which are today industrially feasible.
Therefore, many people consider that pulp mills are going to be the future large scale bioreineries. One example will be the start up in 2017 of the new Metsa mill at Aanekoski in Finland which should
produce both 1.3 million tons of cellulose per year and a series of bioproducts and biofuels, including sulfuric acid, methanol, textile ibres, lignin derivatives, fertilizers, biogas [1].
Figure 1 gives a general scheme of a kraft bioreinery. In this process the wood is treated at high temperature with vapor prior to kraft cooking. During this step named autohydrolysis, the hemicelluloses
are depolymerized and made soluble in water. Part of them is recovered as simple sugars or oligomers which may be the raw material for sugar chemistry [2]. Some of the lignin present in the liquor after
cooking is precipitated and recovered as a source of phenolic compounds. However the drawbacks of the kraft process are not addressed. Moreover, the presence of sulfur in the recovered lignin may be a
problem for subsequent applications. Our recent work has been devoted to the understanding of the reactions taking place during the autohydrolysis step.
Figure 1. Scheme of the kraft bioreinery mill
2.1 Impact of Autohydrolysis on Lignin and Lignin-Carbohydrates Complexes