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The United States, China, and Japan are the greatest producers of printing and writing paper in the world. Between 1996 and 2012, those three countries produced 350 million tons, 238 million tons, and
183 million tons of printing and writing paper, respectively. Hence, the sum of total productions in the United States, China, and Japan equals 771 million tons or it represented 44 per cent of international
printing and writing paper production since the production of printing and writing paper in the world was 1.7 billion tons in the same period.
The production of printing and writing paper in China increased dramatically. From 1996 to 2012, the production of printing and writing paper rose from 5.6 million tons to 25.3 million tons. In other words,
it increased by 19.7 million tons in 16 years. It exceeded the printing and writing paper production in Japan from 2002 onwards and in the United States from 2008 onwards even though the production in
China in 1996 was far below the production in the United States and Japan. The production rates in the United States and Japan decreased from 22.5 million tons to 16.1 million tons 28.4 per cent decrease
and from 10.8 million tons to 8.7 million tons 19.7 per cent decrease, respectively. Even though production of printing and writing paper in China increased dramatically, the rate of consumption of
this paper product was also increased at roughly the same speed. Therefore, most of its production was
aimed to fulil internal demand.
3.3 Use and Production of Packaging Paper
As an emerging economy, China is developing many economic sectors including manufacture. Figure 5 indicates the quantity of packaging paper needed by China to wrap and deliver its products
to customers in different countries. It grew from 14.8 million tons in 1996 to 62 million tons in 2012, more than fourfold. Compared to other countries, China is the largest producer of packaging paper and
raising its production quantity. The growth of packaging paper use in China illustrates that developing of Chinese manufacturing sector was remarkable.
Figure 5 The Highest National Use of Packaging Paper Source: FAOSTAT – Forestry database
The United States, China, and Japan are the largest producers of packaging paper in the world. From 1996 to 2012, the total productions of packaging paper in those three countries are 787 million tons, 558
million tons, and 204 million tons, respectively. Therefore, the sum of total productions in the United States, China, and Japan equals 1.55 billion tons or it accounted for 53 per cent of global packaging
paper production since the world’s production of packaging paper in that period was 2.9 billion tons.
There was a striking growth of packaging paper production in China. Between 1996 and 2012, the production of packaging paper grew from 14.8 million tons to 61.3 million tons. In other words, it
increased by 46.5 million tons in 16 years. Even though the production in 1996 was far below the production in the United States, it surpassed the packaging paper production in the United States from
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2008 onwards. The production rates in the United States and Japan declined slightly from 47.4 million tons to 45.9 million tons 3.2 per cent decrease and from 12.3 million tons to 11.3 million tons 8.3 per
cent decrease, respectively.
Figure 6 The Highest National Production of Packaging Paper Source: FAOSTAT – Forestry database
Even though China was a second largest producer of packaging paper in the world, this country was not the major exporter of packaging paper product. China is not listed in the top ten of packaging
paper exporters. Almost all of its production of packaging paper was used domestically. It could be explained that China is an emerging country that it is boosting many of economy sectors including
manufacturing industry. Almost all of products could be built in China with competitive prices; therefore, the products could penetrate markets in many countries. In order to maintain the quality of the products
in transportation, the good quality of packaging paper is necessary. As a result, although there was a tremendous production of packaging paper in China, most of them was needed to deliver its own
products to global market.
Conclusion
The decline of newsprint consumption rate in these advance countries was because newspaper publishers would likely move to digital formats, and it made a number of newspaper reader move
from paper-based news to internet-based news. People have started to change their reading habit from newspaper to electronic screens. The advance of the Internet technology has stimulated this
transformation of reading habit. The more advance the technology of internet the more comfortable for people to access information. Moreover, technology of electronic screens would make it easy to access
the Internet; consequently, to read news, people would rather choose online newspaper. Furthermore, the change of reading habit could reduce consumption level of newsprint. After the emergence of electronic
readers, the world’s production of newsprint declined.
Béhar et al. 2010: 2 explained that the emergence of digital era has changed the publishing industries. Initially, there were no a comfortable electronic screens for people to read; subsequently, more people
would rather choose printed books, but after the invention of digital devices, many people migrate from printed to digital books. Moreover, Pineault et al. 2008: 42 explained that electronic media is one of
the sources of information that could compete with paper-based information. However, the advance of internet technology could also encourage the use of printing and writing paper. According to Béhar et
al. 2010: 5, digital era would made people have their own virtual library, and in turn it could inspire them to purchase their printed favourite books. Kinsella et al. 2007: 9 claimed that the development
of the Internet technology would raise consumption level of printing and writing paper because paper- based medium is appropriate material to promote business activities such as marketing and advertising.
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Because of this competition, there was no signiicant change world’s consumption of printing and writing paper. The trends of production of printing and writing paper also showed insigniicant change.
According to Meltzer 2014: vi, the advantages of the Internet for large companies in advanced countries are limited in maximizing their capacity, business sectors, and services to their market in the
world. In other words, there would be some limitation of utilizing the full features of the Internet as a foundation to support the global trade. These restrictions range throughout the whole of business chain
supported by the Internet. On the other hand, the Internet offers beneits to support and boost production progress. Firstly, the Internet could advance the level of eficiency in production methods and increase
the effectiveness of management procedures throughout business elements. Secondly, invention of methods in business activities, which is the element of productivity improvement, could be supported
by the Internet technology. Thirdly, the internet could be utilized as a basis for improving productivity progress in the sector of services. Lastly, Meltzer 2014: 5 argued that the Internet could give a chance
for customers to get much information about products that are available locally and globally. Because of these different conditions, some countries experienced the decline of consumption of packaging paper,
but some other countries increased their packaging paper consumption. Oversupply in one country could
fulil demand in other countries. Overall, the impact of Internet to consumption of packaging paper was signiicantly positive.
References
1. Béhar, P., L. Colombani and S. Krishnan 2010 ‘Publishing in the Digital Era: A Bain Company Study for the Forum d Avignon’. Bain Company, Inc.
2. BCG 2007 The Prospects for Graphic Paper. Boston: The Boston Consulting Group.
3. BCG 2010 Turning the Page: How the Digital Revolution is Squeezing Demand for Graphic
Paper. Boston: The Boston Consulting Group. 4. Chiang, J. 2013 ‘IBISWorld Industry Report 32212: Paper Mills in the US’. IBISWorld Inc.
5. Ge, X. and J. Ruan 2013 ‘Integrating Information and Communication Technologies in Literacy Education in China’. Accessed on August 9, 2014 from http:www.ou.edu uschinaICT20
Chinese20 Literacy.pdf . 6. INCPEN 2012
Packaging and the Internet: A Guide to Packaging Goods for Multi-Channel Delivery Systems.
Reading: The Industry Council for Packaging and the Environment.
7. Kinsella, S., G. Gleason, V. Mills, N. Rycroft, J. Ford, K. Sheehan, and J. Martin 2007 ‘The State of the Paper Industry: Monitoring the Indicators of Environmental Performance’, A collaborative
report by the Steering Committee of the Environmental Paper Network. 8. Lei, L. and H. Li 2007 ‘Computer Usage and Demand for PaperPaperboard Products’, Preliminary
Study. Atlanta: Georgia Institute of Technology. 9. Luo, J. 2003 ‘Chinese Newsprint and Printing Writing Paper Industry’. Accessed on July
31, 2014 from http:www.cpbis.gatech.eduilespapersCPBIS-WP-03-0420Luo_Chinese20 Newsprint20 and20Printing20Writing20 Paper20Industry.pdf.
10. Meltzer, J. 2013 ‘The Internet, Cross-Border Data Flows and International Trade’, Issues in Technology Innovation 22: 1-21.
11. Meltzer, J. 2014 ‘Supporting the Internet as a Platform for International Trade: Opportunities for Small and Medium-Sized Enterprises and Developing Countries’, Global Economy and
Development Working Paper No. 69. Washington, DC: Brookings Institution. 12. Moore, G. and J. O’Hear 2008 ‘Paper’s Future Role’,
Paper360º April 2008, p. 16-18. 13. Pineault, D., J. Shane, B. Pellows, J. Hamilton, and S. Adoniou 2008 ‘Demand Drivers for Printing
Paper’. PaperAge.
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RECOVERY OF ACETIC ACID FROM PREHYDROLYSATE FROM A CANADIAN HARDWOOD KRAFT DISSOLVING PULP MILL
Avik Khan
a
, Laboni Ahsan
a
, Xingye An
a, b
, Baobin Wang
a
, Jing Shen
a, b
, and Yonghao Ni
a 1
a
Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
b
Tianjin Key Laboratory of Pulp and Paper, Tianjin University of Science and Technology, Tianjin 300457, China
c
Key Laboratory of Bio-based Material Science and Technology of Ministry of Education, Northeast Forestry University, Harbin 150040, China
1
yonghaounb.ca
ABSTRACT
The utilization of dissolved organics in prehydrolysate PHL to produce value-added chemicals is of interest from the integrated forest bioreinery perspective. This paper presents an overview of research
work on the recovery of acetic acid from prehydrolysate collected from a Canadian hardwood kraft dissolving pulp mill. The acetic acid recovery process consisted of: 1 adsorption using activated carbon
AC or lime mud, to remove lignin, and 2 recovery of acetic acid from the treated PHL TPHL, by using amine-based resin adsorption or amine-based reactive extraction. The use of an amine-based resin
under the conditions studied led to a 98 acetic acid recovery from Model solution MAA and 46 from TPHL. For the amine-based reactive extraction, the Trioctyl amine TOAoctanol system had
80.48, 61.84 and 63.53 acetic acid recovery from MAA 1 model acetic acid solution, PHL and treated PHL TPHL, respectively; subsequently, acetic acid in the organic phase TOA-octanol was
back extracted using a sodium hydroxide solution, while the solvent TOA- octanol was regenerated.
Keywords:
Bioreinery, Prehydrolysate, Bio-chemicals, Acetic acid, Resin adsorption, Reactive extraction, Activated carbon treatment, Lime mud treatment
Introduction
The forest product sectors, especially the pulp and paper industry, have made signiicant contributions to Canadian economic development. The Kraft-based dissolving pulp production technology has
received much attention mostly due to growing market demand from Asian countries, and in Canada, a number of mills have converted to the prehydrolysis kraft dissolving pulp productions in recently years.
Furthermore, the integrated forest bioreinery concept van Heiningen, 2006; Li et al., 2010, aiming to produce bioenergy and biomaterials, besides the traditional pulp and paper products, will allow these
operation’s processes to have more revenue sources Fornell Berntsson, 2012; Huang et al., 2010.
Much RD effort has been devoted to develop effective processes to convert forestry and agricultural biomass into a large spectrum of products; or to recoverseparate chemicals from sustainable bioresources,
biowastes and biomaterials Mao et al., 2008; Mateos-Espejel et al., 2013. The prehydrolysate PHL of Kraft based dissolving pulp process is an attractive source for the same purpose. In current practice,
the liquor is burnt in a recovery boiler. The mostly hemicellulloses containing PHL is not a good source for heat as they have lower heating value than lignin. Therefore, it is desirable to separaterecover the
dissolved organics in PHL as value added products. The main components of the PHL, which is from an Eastern Canadian mill operating a hardwood kraft dissolving pulp production, are listed in Table-1
Shen et al., 2011. In the pre-hydrolysis process, much of the hemicelluloses and some part of lignin are extracted from the wood chips. As shown in Table-1, the total amount of sugar was 50.33 gL,
whereas, acetic acid, lignin and furfural constitute 10.11, 9.22, and 1.43 gL, respectively. Acetic acid is a bulk industrial chemical that has many applications. The demand for acetic acid is increasing by
approximately 3~4 every year. The global demand for acetic acid in 2010 was 9.5 million tons Amidon et al., 2008, and it is desirable to produce acetic acid from renewable biomass.
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Figure-1 Schematic of the acetic acid recovery processes In this paper, we have presented an overview of the research work, on the recovery of acetic acid
from PHL from the kraft based hardwood dissolving pulp production process, that was carried out at the University of New Brunswick in Canada. Two different pathways Figure-1 were adopted to
achieve desired results. As shown in Figure-1, the prehydrolysate was irst treated using absorbent, such as lime mud Shen et al., 2011 and activated carbon Liu et al., 2012, to remove lignin-like material.
The resultant treated prehydrolysate TPHL was then subjected to 1 amine- based resin adsorption Ahan et al., 2014; Ahan et al., 2016, or 2 amine-based reactive extraction Ahsan et al. 2013; Yang et
al. 2013a; Yang et al. 2013b, to recover the acetic acid from the treated PHL TPHL.
Table-1: Chemical compositions of PHL gL Shen et al., 2011 Chemicals in PHL after hydrolysis of wood
Composition gL Sugar
50.33 Acetic acid
10.11 Lignin
9.22 Furfural
1.43
Experimental Materials
Acetic acid purity 99 was obtained from Fisher Scientiic Canada. Industrial prehydrolysate PHL samples were collected from a Kraft-based dissolving pulp mill in eastern Canada. The activated
carbon CR325W-Ultra samples were obtained from Carbon Resources. The weak base resin Purolite A111S was supplied by Purolite International Ltd. Extractant TOA 98 and diluent Octanol 99.99
were obtained from Sigma Aldrich Chemical Co. and Fisher Scientiic, respectively.
Methods Activated Carbon AC and Resin Treatment
The
PHL was treated with powdered activated carbon AC at room temperature for 5 h. The weight ratio of PHL to AC was 20:1, and the shaking speed was 150 rpm. All resins and different volumes of 1
model acetic acid MAA solutions and AC treated PHL TPHL were taken with different ratios 1:5 to
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1: 20 for adsorption study in a thermostatic shaker at 25 °C. Agitation was provided at 150 rpm for 1 hr. The amount of adsorbate on adsorbent and in solution at equilibrium can be represented as:
q
e
gg = C
o
-C
e
VW-------------------- 1 X
e
= C
e
V----------------------------------- 2 Where C
o
and C
e
gL are the acetic acid concentration at initial and equilibrium, respectively. VL is the volume of solution and Wg is the weight of adsorbent used in the experiment. Regeneration
desorption was done in a same manner of adsorption with 4 NaOH at 1 to 10 resin to alkali solution mass ratio, 1 hour and 150 rpm of shaking speed.
Extraction Methods
Equal weights of an organic solvent different ratio mixture of amine and octanol and an aqueous solution of 1 acetic acid model or PHL or TPHL were charged in Erlenmeyer lasks separately. These
were then stirred by magnetic bar at 500 rpm for 30 minutes at 25 °C, followed by centrifuging at 3,000 rpm for about 5 minutes to separate the two phases. Afterwards, back extraction was done adding a
different mole ratio of NaOH solution to the organic extracted solvent at various weight phase ratios following the same stirring speed, time, temperature, centrifuging speed used in the extraction stage.
Acetic Acid and Furfural Analysis
The initial and equilibrium acid concentrations of furfural and acetic acid were determined using
1
H NMR spectroscopy. All quantitative acetic acid
1
H NMR spectra were recorded at 298 K in H
2
O:D
2
O 4:1 using a VarianAgilent INOVA 300 NMR spectrometer operating at a frequency of 299.838 MHz.
Lignin Analysis
The lignin contents of the original PHL and TPHL were measured based on the UVvis spectrometric method at a wavelength of 205 nm Tappi UM 250 Liu et al., 2012.
Sugar Analysis
The sugar contents in the pre-hydrolysis liquor and the rafinate were determined by using an Ion Chromatography with a Pulse Amperometric Detector and CarboPacTM PA1 column Dionex-300,
Dionex Corporation, Canada.
Results and Discussion Removal of Lignin from PHL by Adsorption using Activated Carbon or Lime Mud
Activated Carbon Treatment
It is desirable to obtain a high degree of lignin removal to justify the application of PHL in bioreinery applications Wei et al., 2006. An activated carbon sample, CR325W-Ultra with a high surface area
1350 m
2
g, was chosen to carry out the AC treatment. The effects of AC treatment on the removal of lignocelluloses are presented in Table-2 Ahsan et al., 2016. We can see that the AC treatment decreased
the lignin and furfural content in PHL by 81.8 and 60.1, respectively. Liu et al. 2011 also reported substantial removal of lignocelluloses from PHL due to AC treatment Liu et al., 2011.
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Table-2: Characterization of PHL before and after CR325W-Ultra treatment Ahsan et al., 2016 or lime mud treatment Shen et al., 2011
Activated Carbon Treatment
Lime Mud Treatment Component
PHL TPHL
Removal PHL
TPHL Removal
Lignin gL 10.11
1.85 81.8
9.22 8.18
11.3 Acetic acid gL
10.18 9.82
3.22 10.11
8.16 16.4
Furfural gL 1.48
0.59 60.1
1.43 1.13
21.3 Total sugars gL
59.12 58.69
1.04 50.33
49.93 0.8
Lime mud treatment
Besides activated carbon treatment, lime mud treatment can also be applied to obtain the TPHL. Shen et al. 2011 have recovered dissolved lignocelluloses successfully from the prehydrolysate of the kraft-
based dissolving pulp production process by adsorption to lime mud produced in the causticizing plant of the kraft process. The effect of lime mud treatment on the removal of lignocelluloses are presented
in Table-2 Shen et al., 2011. We can see that the lime mud treatment decreased the lignin and furfural content in PHL by 11.3 and 21.3, respectively.
Recovery of Acetic Acid using Amine- Based Resin Adsorption
At this stage our main objective was to recover acetic acid from the TPHL. Purolite A111S, a weak- base anionic resin with tertiary amine functional groups, was chosen to accomplish the objective. Its
Purolite A111S polymer structure is based on a polystyrene-divinyl benzene matrix. From Figure-2, we can see that the adsorbent-to-adsorbate ratio had a signiicant impact on adsorption eficiency. The
adsorption of acetic acid was increased with the increase of adsorbent dose. The mass ratio of TPHL or MAA solution to resin was 20:1, 10:1, 5:1, 4:1, and 3.3:1. For TPHL, the maximum adsorption 57
was observed at a resin-to-TPHL ratio of 3.3. At 10:1 aqueous-to-resin dose, the adsorption capacity reached 98 for 1 MAA, which was 1.5 meqg of dry resin, but thereafter absorption became slower.
Acetic acid adsorption was 46 from 8.17 gL of TPHL, which was 0.63 meqg of dry resin only at 10:1 aqueous-to-resin dose. The experimental adsorption capacity of the MAA sample per the manufacturer
was close to the original total capacity of the A111S, which is 1.7 meqg of dry resin. The lower recovery from TPHL may be attributed to the presence of sugars and lignin in addition to acetic acid in the TPHL,
which may hinder acetic acid adsorption.
Figure-2: Effect of adsorbent on the adsorption of acetic acid from the TPHL and MAA at 25 °C for 1 hr Ahsan et al., 2016
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Regeneration of Resin
Regeneration of the resin is critical from an economic perspective. Table-3 shows the amount of acetic acid was desorbed from the resin by using 4 NaOH. Higher alkali concentration removed more
acetic acid from the resin, but this condition could have detrimental effect on the properties of resin Lv et al., 2012. Therefore, a 2~4 NaOH seems to be the optimized concentration for this purpose.
From Table-3, it was clear that desorption increased with increasing temperature. At room temperature, 78 and 66 acetic acid of MAA and TPHL were desorbed as sodium acetate from adsorbed resins,
respectively, which increased to 90 and 84 with increasing temperature by 20 °C. The lower desorption for the TPHL was obviously due to presence of lignin and other dissolved organics which
were also adsorbed and block the pore of resin.
Table-3: Desorption of acetic acid by 4 NaOH solution at 1: 10 ratios of resin and alkali solution for 1 hr at 150 rpm
Feed stock
Desorption of acetic acid from resin 25 °C
35 °C 45 °C
Desorbed Concentration in
iltrate gL
Desorbed Concentration in
iltrate gL
Desorbed Concentration
in iltrate gL MAA
78 7.02
85 7.65
90 8.10
TPHL 66
2.64 74
2.96 84
3.36
Recovery of Acetic Acid by Reactive Extraction Effect of Amine Concentration
The second approach was to follow the reactive extraction approach using tri-n-octylamine TOA as the solvent. Table-4 illustrates the inluence of amine to acid stoichiometric ratio on the extraction
of acetic acid from the model acetic acid solution. The results presented in Table-4 are in terms of distribution coeficient K
D
, extraction eficiency, and overall loading factor. The reactive liquid-liquid extraction of acetic acid HA with TOA B gives a reaction complex
BHA which remains in organic phase and may be represented by: HA
aq
+ B
org
= BHA
org ----------------------------------
3 The distribution coeficient, K
D
, is deined as the ratio of organic acid in the two phases by Datta et al., 2011:
K
D
= [HA]
org
[HA]
aq ------------------------------------
4 Table-4 shows that the distribution coeficient, K
D
value increased with increasing stoichiometric ratio and this shows shifting of acetic acid to organic phase from the aqueous phase. At the stoichiometric
ratio of 1, the K
D
value was 4, where extraction of acetic acid was around 80. The highest extraction of acetic acid 92 was achieved at the molar ratio of 3, when K
D
value was 12. Obviously, more base in solution can separate more acid, which is also supported by other results Sahin et al., 2009.
Diluents has an inluence on the formation of acid-amine complexes, and therefore on the values of the distribution coeficient. The formation of an acid-amine complex is promoted by the dipole-dipole
interactions between diluent and complex; andor by the complex-diluent hydrogen bond Bízek et al., 1993.
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Table-4: Effect of TOA concentration on extraction of 1 MAA organic to aqueous phase weight ratio is 1
Amine to acetic acid molar ratio
Recovery of acetic acid Overall Loading factor,
[acid]org [amine]org Distribution co-eficient,
K
D
[acid]org[acid]aq 3.0 to 1
1.5 to 1 1.0 to 1
0.75 to 1 0.5 to 1
0.25 to 1 0.1 to 1
92.31±0.34 86.20±0.78
80.48±0.97 74.14±0.15
67.30±0.67 50.51±0.78
44.03±0.88 0.32
0.60 0.84
1.03 1.41
2.07 4.20
12.0 6.22
4.12 2.86
2.06 1.02
0.79
It was also observed that the loading ratio increased with decreasing amine concentration. But the total extraction of acetic acid decreased with the decrease of TOA concentration. It was also noticeable that
the value of the loading factor was more than 1 when the amine is less than acetic acid in stoichiometric ratio, which was referred as overloading Tamada et al., 1990. The same trend was also observed by
Reisinger Reisinger King, 1995 in extraction of acetic acid with Amberlite LA-2 a secondary amine where overloading sustained for lower stoichiometric amine concentration. A higher loading factor at
1 stoichiometric ratio can be explained by the formation of acetic acid dimer as shown in Figure-3. It is also evident from Figure-3, that via hydrogen bonding a second acetic acid can be complexed forming
complex II, which is responsible for the loading factor of 1. Noting that the acid-amine complex is stabilized by the hydrogen bond by diluents Grzenia et al., 2012.
Figure-3: Complex formation due to over loading; I 2, 1 acetic acidamine complex and II 3, 1 acetic acidamine complex, respectively Tamada et al., 1990
Extraction of Acetic Acid from PHL and TPHL
From Figure-4, it can be observed that distribution coeficient of acetic acid is much lower in PHL and TPHL than 1 MAA. At the stoichiometric ratio of 1, the K
D
value was 1.62, which was equivalent to 61.85 extraction from PHL Table 5. Activated carbon treated PHL TPHL removed 80 of
lignin, 90 of furfural, consequently slightly increased the distribution coeficient, K
D
to 1.74, which was equivalent to 63.53 of acetic acid extraction. The lower extraction of acetic acid from the PHL
and TPHL may be due to the presence of furfural, lignin and other minor impurities like hydroxymethyl furfural HMF, formic acid and levulinic acid in PHL and TPHL.
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Figure-4: Variation of acetic acid extraction from PHL, TPHL and 1 MAA with stoichiometric mole ratio of amine and acetic acid at equal mass of two phase extraction
Figure-5: Effect of pH on the extraction of acetic acid from the PHL and TPH Table-5: Effect of TOA concentration on extraction of acetic acid from PHL and TPHL organic to
aqueous ratio 1
Sample Amine to acetic acid
Recovery Distribution ratio [acid]org
[acid]aq PHL
1.5 to 1 1.0 to 1
0.5 to 1 65.03±1.34
61.84±1.78 52.53±1.23
1.86 1.62
1.11 TPHL
1.5 to 1 1.0 to 1
0.5 to 1 67.54±1.55
63.53±4.55 55.69±1.76
2.08 1.74
1.26
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The extraction of furfural, HMF, lignin, formic acid and levulinic acid were reported by Grzenia et al Grzenia et al
., 2010, where TOA and octanol used with polypropylene membrane to detoxiied dilute sulfuric acid treated corn Stover hydrolysate. To overcome this fact the impurities must be removed prior
to extraction as much as possible; sometimes combination of different diluents can be used to enhance distribution coeficient, increasing amine concentration up to a certain amount also helps to increase
extraction Harington Hossain, 2008. The undissociated form of acetic acid increased with decreasing the pH of the solution. At pH values below the pKa 4.76 of acetic acid, the protonatedundissociated
form of acetic acid is removed by forming an ion pair with amine Grzenia et al., 2008. Extraction of acetic acid decreases rapidly as the pH of solution approaches the pKa because the anionic form is
much better solvated with water than octanol. This hypothesis was further veriied by decreasing pH value of PHL and TPHL by acetic acid, and total acetic acid concentration was considered in calculating
acetic acid extraction. The recovery of acetic acid increased by 3.82 and 6.68 for PHL and TPHL, respectively, with decreasing pH value to 2.6 Figure-5. From the above discussion, one may conclude
that the extraction eficiency of acetic acid from PHL and TPHL was lower than the MAA because of comparatively higher pH in the PHL and TPHL 4.25 vs 2.62 and other impurities which may compete
with acetic acid for the binding sites of organic phase.
The acetic acid can be back-extracted by temperature swing, diluent swing, pH swing, distillation, volatile tertiary amine, such as trimethylamine and regenerated solvent Ma et al., 2006. Regeneration
of amine-carboxylic acid extracts can also be achieved by back-extraction of the acid into an aqueous solution of a strong base such as NaOH which sometime referred as pH swing regeneration.
Back Extraction of Acetic Acid from MAA
Table-6 shows the effect of volume of organic phase to aqueous phase on the back extraction of acetic acid from the loaded organic phase. At the organic to aqueous phase ratio of 1, the back extraction
of acetic acid was 97. An increase in the organic to aqueous ratio decreased the acetic acid recovery. Table-6: Effect of organic to aqueous phase ratio on the back extraction of acetic acid of MAA from
the loaded organic phase of MAA Mole ratio of NaOH to acid was 1
Alkali Orgaqueous
Acetic acid recovery ConcentrationgL
NaOH 40
20 10
5 2
1 0.5
46.44 68.8
76.0 95.4
97.44 97.13
29.6 150.8
118.1 65.6
40.8 16.6
8.4 2.5
As shown in Table-6, at the organic to aqueous ratio 5, the acetic acid recovery was 95.4 which was equivalent to 40.8 gL sodium acetate concentration. An acetic acid concentration of 150.8 gL was
obtained in an organic to aqueous ratio of 40, and the HAc recovery was 46.4. A lower recovery of acetic acid at the higher organic to aqueous phase may be attributed to lower interaction of acid and
alkali. Therefore, a thorough mixing would be important to achieve a good HAc recovery for the system, which was supported by our experimental results total volume by factor 4, the back extraction increased
by almost 2 for the better contact. Also, the lower HAc recovery at a higher Orgaqueous phase ratio
may be compensated by a higher alkali to acid ratio extraction eficiency increased by 2-3.
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Recycling of Regenerated TOA
Recycling of the regeneratedrecovered solvent used in the process is an important issue in reactive extraction to make a viable process. To ind the extraction eficiency of regenerated solvent after back
extraction with sodium hydroxide, the same MAA and TPHL samples were extracted with regenerated TOAOctanol and its HAc extraction eficiency was determined; subsequently, the HAc recovery in the
NaOH regeneration step was also determined, and results are given in Table-7.
Table-7: Effect of solvent recycling on extraction and back extraction of acetic acid Ahsan et al., 2013
Recycle time Acetic acid Extraction Eficiency
Acetic acid back extraction Eficiency MAA
TPHL MAA
TPHL 80.83
64.47 97.95
90.06 1
80.32 64.22
97.83 90.12
2 80.89
64.57 97.30
89.61 3
79.90 64.51
97.86 89.69
4 80.77
64.70 97.11
89.76 5
80.09 64.51
97.31 89.82
6 80.54
64.34 97.20
89.75 7
80.08 64.41
97.01 89.88
8 79.67
63.98 97.44
88.27 9
79.22 63.45
97.05 88.45
It’s shown that the HAc extraction eficiency in the extraction step and the HAc recovery in the back-extraction step remained essentially the same for the 9-cycling time studied. For the TPHL, the
HAc extraction eficiency and the HAc recovery in the back-extraction step were 64.66 and 89.64, respectively when using fresh TOAOctanol, while they were 63.45 and 88.43, respectively after the
ninth recycling. The above results indicate that the recovered TOA-octanol can be successfully reused recycled in the process.
Conclusions
This paper highlights two potential separation technologies to recover acetic acid from the prehydrolysate PHL of the kraft-based dissolving pulp process. First, the adsorption concept, using
activated carbon or lime mud, was followed to remove lignin present in the PHL. Then, two different approaches, the amine based resin treatment or the reactive extraction, were used to recover acetic acid.
For the amine based resin treatment process, at equilibrium, the adsorption of acetic acid was 93 mgg for MAA sample and 38.23 mgg for TPHL at 25 °C. For the reactive extraction process using TOA
octanol, the results showed that only 6 equal mole ratio of acid and amine of TOA can recover 80.48, 61.85, 63.53 of acetic acid from MAA, PHL and TPHL, respectively. To recover the acetic
acid from the TOAoctanol and to reuse the extractant, a back-extraction was performed with aqueous sodium hydroxide solution. At equal mole and phase ratio, the back extraction yield of 97, 83 and 90
was obtained for MAA, PHL and TPHL, respectively. It was concluded that the proposed processes have potential in recovering acetic acid from the prehydrolysate.
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Acknowledgement
The authors gratefully acknowledge the Grants of NSERC and Atlantic Innovation Fund AIF for inancing this project.
References
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trioctylamineoctanol system. Industrial Engineering Chemistry Research, 5226, 9270-
9275. 2. Ahsan, L., Jahan, M.S., Ni, Y. 2014, Recoveringconcentrating of hemicellulosic sugars and
acetic acid by nanoiltration and reverse osmosis from prehydrolysis liquor of kraft based hardwood dissolving pulp process. Bioresource Technology, 155, 111-115.
3. Ahsan, L., Jahan, M. S., Yang, G., Ni, Y. 2016. Adsorption of acetic acid from pre-hydrolysis liquor from kraft-based dissolving pulp production using amine-based resin.
J-FOR. Journal of Science Technology for Forest Products and Processes, 53, 20-26.
4. Amidon, T. E., Wood, C. D., Shupe, A. M., Wang, Y., Graves, M., Liu, S. 2008. Bioreinery:
Conversion of woody biomass to chemicals, energy and materials. Journal of Biobased
Materials and Bioenergy, 22, 100-120. 5.
Bízek, V., Horáček, J., Koušová, M. 1993. Amine extraction of citric acid: effect of diluent. Chemical Engineering Science, 488, 1447-1457.
6. Datta, D., Kumar, S., Wasewar, K. L. 2011. Reactive extraction of benzoic acid and pyridine-3-carboxylic acid using organophosphoric and aminic extractant dissolved in binary
diluent mixtures. Journal of Chemical Engineering Data, 568, 3367-3375.
7. Fornell, R., Berntsson, T. 2012. Process integration study of a kraft pulp mill converted to an ethanol production plant–Part A: Potential for heat integration of thermal separation units.
Applied Thermal Engineering, 35, 81-90. 8. Grzenia, D. L., Dong, R. W., Jasuja, H., Kipper, M. J., Qian, X., Wickramasinghe, S. R.
2012. Conditioning biomass hydrolysates by membrane extraction. Journal of Membrane
Science, 415, 75-84. 9. Grzenia, D. L., Schell, D. J., Wickramasinghe, S. R. 2008. Membrane extraction for removal
of acetic acid from biomass hydrolysates. Journal of Membrane Science, 3221, 189-195.
10. Grzenia, D. L., Schell, D. J., Wickramsinghe, S. R. 2010. Detoxiication of biomass
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11. Harington, T., Hossain, M. M. 2008. Extraction of lactic acid into sunlower oil and its
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12. Huang, H.-J., Ramaswamy, S., Al-Dajani, W. W., Tschirner, U. 2010. Process modeling and analysis of pulp mill-based integrated bioreinery with hemicellulose pre-extraction for ethanol
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13. Li, H., Saeed, A., Jahan, M.S., Ni, Y., Van Heiningen, A. 2010, Hemicellulose removal from hardwood chips in the pre-hydrolysis step of the kraft-based dissolving pulp production process.
Journal of Wood Chemistry and Technology, 30 1, 48-60. 14. Liu, X., Fatehi, P., Ni, Y. 2011. Adsorption of lignocelluloses dissolved in prehydrolysis
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17. Ma, C., Li, J., Qiu, J., Wang, M., Xu, P. 2006. Recovery of pyruvic acid from biotransformation solutions.
Appl Microbiol Biotechnol, 703, 308-314.
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18. Mao, H., Genco, J., Yoon, S.-H., Van Heiningen, A., Pendse, H. 2008. Technical Economic Evaluation of a Hardwood Bioreinery Using the. Journal of Biobased Materials and Bioenergy,
22, 177-185. 19. Mateos-Espejel, E., Radiotis, T., Jemaa, N. 2013. Implications of converting a kraft pulp mill
to a dissolving pulp operation with a hemicellulose extraction stage. Tappi Journal, 122, 29-38. 20. Reisinger, H., King, C. J. 1995. Extraction and sorption of acetic acid at pH above pKa to form
calcium magnesium acetate. Industrial Engineering Chemistry Research, 343, 845-852.
21. Sahin, S., Bayazit, S. S., Bilgin, M., ̇nci, I. s. 2009. Investigation of formic acid separation from
aqueous solution by reactive extraction: effects of extractant and diluent. Journal of Chemical
Engineering Data, 554, 1519-1522. 22. Shen, J., Fatehi, P., Soleimani, P., Ni, Y. 2011. Recovery of lignocelluloses from pre-hydrolysis
liquor in the lime kiln of kraft-based dissolving pulp production process by adsorption to lime mud. Bioresour Technol, 10221, 10035-10039.
23. Tamada, J. A., Kertes, A. S., King, C. J. 1990. Extraction of carboxylic acids with amine extractants. 1. Equilibria and law of mass action modeling.
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24. Yang, G., Jahan, M.S., Ahsan, L., Zheng, L., Ni, Y. 2013a Recovery of acetic acid from pre- hydrolysis liquor of hardwood kraft-based dissolving pulp production process by reactive extraction
with triisooctylamine, Bioresource Technology, 138, 253-258.
25. Yang, G., Jahan, M.S., Ahsan, L., Ni, Y. 2013b. Inluence of the diluent on the extraction of acetic
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van Heiningen, A. 2006. Converting a kraft pulp mill into an integrated forest bioreinery. Pulp and Paper Canada, 1076, 38-43.
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SUBSTITUTION OF BCTMP FOR HARDWOOD KRAFT PULP IN WRITING AND PRINTING PAPER
Lies Indriati
a1
, Angga Kesuma
b2
, Juliani
b3
a
Center for Pulp and Paper, Jl. Raya Dayeuhkolot 132, Bandung 40258, Indonesia
b
Academy of Pulp Paper Technology, Jl. Raya Dayeuhkolot 132, Bandung 40258, Indonesia
1
liesinaggmail.com
2
anggakesuma1310gmail.com
3
juliani_yapymail.com
ABSTRACT
Printing and writing paper are generally made from chemical pulps. Current papermaking technology developments have allowed the use of 100 hardwood bleached kraft pulp HBKP as iber source.
However, to further enhance the competitiveness of products, paper industries keep trying to reduce their production cost. The use of less expensive high yield pulps such as BCTMP bleached chemo-
thermomechanical pulp is an interesting alternative. Some advantages of using BCTMP include high bulk, good opacity, and high stiffness. The laboratory experiments on substitution of BCTMP for HBKP
from
Acacia mangium have been carried out with various composition of furnish 0-15 BCTMP and 100-85 HBKP and PFI reining revolutions of 0-3500. Before mixing, the HBKP was reined up
to certain freeness, while it was no reining for BCTMP. Handsheets of 70 gsm were made from all composition variations and then tested for some physical and optical properties. In addition, in order
to optimize the iber development, separate-reining and combine-reining of BCTMP and HBKP have been investigated as well. Combine-reining was implemented for the pulps composition of 7 BCTMP
and 93 HBKP. The results showed that the higher the BCTMP composition resulted in higher bulk, opacity and air permeability, but lower in smoothness, brightness, and physical strength. Combine-
reining of 7 BCTMP and 93 HBKP improved opacity and physical strength of handsheet. At certain freeness, combined-reining requires less energy than that of separate-reining.
Keywords : BCTMP ; hardwood bleached kraft pulp ; Acacia mangium ; combine-reining, separate-
reining
Introduction
The mixture of softwood bleached karft pulp SBKP and hardwood bleached kraft pulp HBKP are commonly utilized as ibre source of ine writing and printing paper. The content of SBKP is typically
ranges from 5 to as high as 50 to enhance the physical strength of paper, while the rest 50 to 95 is HBKP for improving paper formation, smoothness and printability [1]. The development of
papermaking technology recently has allowed the use of 100 of HBKP for ine writing and printing paper production. Some paper mills in Indonesia have reported the use of 100 HBKP as their ibre
source. However, in order to further enhance their product competitiveness, paper industries keep trying in reducing their production cost. Besides by the increasing iller content of paper [5], the usage of
high yield pulp HYP for substitution of HBKP has been shown recently as one of effective way in reducing their production cost [1-5]. HYP has been moving towards optimizing the production process
to tailor-made HYP with some speciic pulp properties for a speciic end-use in paper and board [4]. It was reported that the strength and brightness of HYP can be made in similar to HBKP with the unique
features such as high bulk, large surface area, and high ines content [1]. HYP is pulp that optimizes the use of trees by utilizing a mechanical process with reiner plates
in order to separate and extract the ibres from the wood [6]. HYP‘s mechanical pulping process has the advantage of converting approximately 90 of wood into pulp, versus approximately 45-50
converted using chemical pulping process [6]. The HYP production process includes wood chips pre- treatment, reining, screening and cleaning, bleaching, drying, and pressing into a bale. The TCF totally
chorine-free bleaching process is applied for HYP production [6]. The terms BCTMP bleached chemo-
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thermomechanical pulp and HYP are the two terms that almost synonymous. BCTMP is the technical name used to describe one speciic and common type of mechanical pulping process that can be used to
produce HYP [6]. BCTMP is high yield bleached mechanical pulp which produced by treating wood chips with slight
amount of chemicals, usually sodium sulphite, and steam before mechanical deiberation. The bleaching process uses non lignin destructive bleaching agent such as ozone or peroxide to retain yield [7]. The
BCTMP technology is used for both softwood and hardwood [7, 8]. Generally, the pulping sequences include soaking wood chips in chemical followed by steaming and reining of wood chips [7]. Both
softwood and hardwood BCTMP is a TCF pulp which use peroxide as a bleaching agent to levels between 60-80 of ISO brightness; even more there is a hardwood BCTMP with higher brightness, as
high as 80-90 ISO. High brightness BCTMP is usually used for ine coated and uncoated writing and printing paper, while the lower one is used as a part of hardwood kraft replacement for tissue and towel
production [7]. The use of BCTMP for paper furnish has a limitation in relation with paper permanence due to its high lignin content which resulted in yellowing of paper [2, 5, 8, 9]. That’s why the lignin
content below 1 is required for paper with high brightness stability [2, 5, 8].
Numerous studies have tried the usage of BCTMP for substitution of HBKP in lightweight writing and printing paper grades. The rate of HYP substitution of 5 to 15 in HBKP is reported for coated
paper, while for uncoated paper the range is 10 to 25 [4]. The substitution of HYP up to 30 for HBKP in the presence of 50 SBKP reported was not impaired the strength and structure properties of sheets
[1, 3]. Substitution of HBKP with HYP is reported reducing furnish cost while increasing paper bulk, opacity and stiffness [3, 4, 5]. At a given paper caliper, HYP can be used to reduce grammage, while
at a given grammage, the higher bulk sheets contain HYP may increase paper stiffness. Due to its high
ines content, HYP may improve sheet formation, but the surface smoothness of paper may be affected. HYP ibres tend to be high in wall-thickness and coarseness that cause the loss of paper smoothness [4].
Further reining treatment of HYP to optimize the mophology of HYP ibres have been studied. The combine reining on mixed furnish of BCTMP and Eucalyptus bleached kraft pulp have been compared
with its separate reining. This resulted that combine reining produce handsheets with improved smoothness and physical strength, while no differences in opacity and light scattering coeficient than
that of separate reining [4]. This paper reports the laboratory experiments on the inluence of BCTMP substitution for
Acacia mangium bleached kraft pulp on handsheets properties in the absence of SBKP. In addition, the effect of separate reining and combine reining of mixed furnish is reported as well.
Experimental Materials
In this investigation, the imported BCTMP from Canada and HBKP of Acacia mangium HBKP
from integrated pulp and paper mill in Riau Province, Indonesia, were used.
Methods Experiment 1: Reining of pulp
BCTMP and HBKP were soaked in distilled water for about 4 hours and then repulped in pulp disintegrator. The separate reining of each pulps was carried out in PFI mill to 0, 500, 2000, and 3500
revolutions and then tested for freeness respectively using Canadian Standard Freeness Tester.
Experiment 2: Furnish Mixing
Reined HBKP of each revolution was mixed with unreined BCTMP with the composition as listed in Table 1. The handsheets of 70 gsm from each mixture were then made using Estenit Handsheet
Former based on SCAN Method. After being conditioned at least for 24 hours in temperature of 23+1
o
C and 50+2 RH, the handsheets were tested for bulk, air permeability, roughness, brightness, opacity,
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tensile index, and internal bonding. The sheet bulk was calculated by dividing the sheet thickness with its grammage, as well as the tensile index which was calculated by dividing the tensile strength with its
grammage.
Table 1. Furnish composition
Code Unreined
BCTMP Reined HBKP
0 rev. 500 rev.
2000 rev. 3500 rev.
1A-D 100
2A-D 7
93 3A-D
10 90
4A-D 12
88 5A-D
15 85
Experiment 3: Combine-Reining
In order to study how the combine-reining of BCTMP and HBKP affect the sheet properties, the mixture of 7 of BCTMP with 93 HBKP was reined simultaneously in PFI mill to 500, 2000, and
3500 revolutions. The handsheets of 70 gsm from reined mixed furnish were also made and then conditioned and tested for the same properties with that of handsheets from separate-reining.
All measurements of pulp and sheets properties were conducted according to the relevant ISO standard methods, except the internal bonding of sheet was measured according to TAPPI Test Method.
Results and Discussion Experiment 1: Reining of BCTMP
Freeness of BCTMP and Acacia mangium bleached kraft pulp HBKP reined separately and its
combined reining are shown in Fig. 1. Eventhough the initial freeness of HBKP is lower than BCTMP, the freeness reduction of HBKP during reining was lower than that of BCTMP. In separate reining, at
the 500 reining revolution, the freeness of BCTMP decreased signiicantly from 531 mL CSF to 264 mL CSF, while HBKP decreased from 449 mL CSF to 346 mL CSF. For this reason, the experiment of
HBKP substitution by BCTMP was conducted by mixing the reined HBKP with unreined BCTMP.
Fig 1. Freeness of BCTMP and HBKP
Se-Re Fig 2. Bulk of mixed
furnish Fig. 3. Air
permeability of mixed furnish
Fig. 4. Roughness of mixed furnish
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Fig. 5. Brightness of mixed furnish
Fig. 6. Opacity of mixed furnish
Fig. 7. Tensile index of mixed
furnish Fig. 8. Internal
bonding of mixed furnish
Experiment 2: Furnish Composition
Effect of mixed furnish with various revolution of HBKP reining on handsheet properties are shown on Fig. 2-8. The results showed that reining revolution give a signiincant effect on sheet
properties. The increase of reining revolution reduced the handsheet bulk, air permeability, roughness, brightness and opacity; while it increased the tensile index and internal bonding as well. As indicated by
the reduction of its freeness along with the increasing of reining revolution see Fig. 1 for HBKP, the reining of HBKP will increase iber lexibility and ines content which affect the reduction of sheet bulk,
air permeability and roughness. Reining of pulp may increase the ibrillation of iber which increases the strength properties of paper produced. The improvement of sheet strength were also shown in Fig. 7
and 8 where the HBKP were reined before being mixed with BCTMP The increasing BCTMP in mixed furnish increased the handsheet bulk, air permeability, and
roughness; while the handsheet brightness, tensile index and internal bonding were reduced. There was no signiicant effect to handsheet opacity.
In the absence of long iber, the use of 7 BCTMP for substitution of HBKP resulted the handsheet with optimum physical and optical properties, while the reduction of strength properties were still
tolerable. This composition then was studied further in the experiment of combine reining of BCTMP and HBKP.
Fig. 9. Freeness of Co-ref
BCTMP+HBKP Fig. 10. Bulk of
mixed furnish co- ref
Fig. 11. Air permeability of
mixed furnish co- ref
Fig. 12. Roughness of mixed furnish
co-ref
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Fig. 13. Brightness of mixed furnish co-
ref Fig. 14. Opacity of
mixed furnish co- ref
Fig. 15. Tensile index of mixed
furnish co-ref Fig. 16. Internal
bonding of mixed furnish co-ref
Experiment 3: Combine Reining
As shown in Fig. 9, reining of mixed furnish at the composition of 7 BCTMP and 93 HBKP combine-reining resulted almost similar trend line of freeness reduction with the 100 HBKP. This
result indicated that the freeness reduction was attributed totally to the HBKP reining. As stated before, the reining of BCTMP it self will dramatically reduced its freeness during the initial period of reining;
in this study was during 500 reining revolutions. The use of BCTMP for substitution of HBKP is advantageous in some paper properties. However,
there are some disadvantages particularly for paper strength properties. Reining is the main mechanical treatment of iber to improved the strength of paper produced. In the initial trial, the unreined BCTMP
was mixed with HBKP which was reined at various reining revolution. To improve further the handsheet properties, the combine-reining of BCTMP and HBKP in certain composition were studied.
The handsheet properties resulted from combine reining of 7 BCTMP and 93 HBKP in various reining revolution are shown in Fig, 9-15. The results showed that combine-reining improved the
handsheets’ smoothness, opacity, tensile index, and internal bonding; and at the same time, it reduced the handsheets’ bulk, air permeability, and brightness.
Conclusion
Reining of BCTMP reduced its’ freeness dramatically; while the reduction of HBKP freeness was slower than that of BCTMP. In the absence of long iber, 7 BCTMP may substitute HBKP while retaining
the sheet properties. In general, the use of unreined BCTMP as substution of reined HBKP increased bulk, air permeability, smoothness and opacity, but reduced brightness and strength preperties. Variation
of reining revolution reduced bulk, air permeability, brightness opacity; however it improved sheet smoothness and strength. The freeness trend line of 7 BCTMP and 93 HBKP mixture combined
reining was almost similar to HBKP, and improved sheet smoothness, opacity strength.
References
1. Hu, K., Ni, Y., Zhou, Y., Zou, X. 2006. “Substitution of hardwood kraft with aspen high-yield pulp in lightweight coated wood-free papers: Part I. Synergy of basestock properties,” Tappi J. 53, 21-
26. 2. Chen, Q., Ni, Y., He, Z. 2012. “Using cationic polymers to improve alkenyl succinic anhyfride
ASA sizing eficiency in high-yield pulp containing furnish,” BioResources 73,3948-3959. 3.
Hu, K., Ni, Y., Zou, X. 2004. “Substitution of aspen high-yield pulp for hardwood kraft pulp in ine papers and its effect on AKD sizing,” Tappi J. 38, 13-16.
4. Gao, Y., Huang, F., Rajabhandari, V., Li, K., Zhou, Y. 2009. “Effect of separate reining and co-
reining of BCTMPKP on paper properties,” Pulp and Paper Canada JulyAugust, 28-33.
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5. Pruzynski, P., Sirois, D. 2012. “Increase high-yield pulps in ine paper furnish,” RISI www.
sicemsaga.comengimg_newsincrease20high-yiled20pulps20fine20paper20furnish. pdf
6. http:temcell.tembec.comenfaqs 7. http:www.paperonweb.comgradepl.htm
8. Cannell, E., Cockram, R. 2000. “The future of BCTMP,” Pulp Paper legacy.risiinfo.comdb_
areaarchivep_p_mag20000005feat2.htm 9. Pu, Y., Anderson, S., Lucia, L., Ragauskas, A.J. 2003. “Fundamentals of photobleaching lignin.
Parta I: Photobehaviours of acetylated softwood BCTMP lignin,” Journal of Pulp and Paper Science
2912, 401-406. 10. Anonymous 2000. “BCTMP: A pulp for all reasons?,”
Pulp and Paper Canada http:www.pulpand papercanada.comnewsbctmp-a-pulp-for-all-reasons-1000106738
11. Li, K., Lei, X., Lu, L., Camm, C. 2010. “Surface characterization and surface modiication of
mechanical pulp ibres,” Pulp Paper Canada, JanuaryFebruary, 28-33.
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ISOLATION AND SCREENING OF THERMOPHILIC XYLANOLYTIC BACTERIAL STRAINS FROM INDONESIAN HOT SPRING
Krisna Septiningrum
1
, M. Khadai, Saepulloh
Center for Pulp and Paper, Jl. Raya Dayeuhkolot No. 132, Bandung 40258, Indonesia
1
krisnabiogmail.com
ABSTRACT
Isolation of xylanolitic bacteria for hemicellulose extraction in paper-grades pulp conversion into dissolving pulp has been conducted. Xylanase was screened from bacteria which was isolated from
geothermal spring sediments from Indonesia. There are 21 bacteria at 60° C and 10 bacteria at 50° C showed positive result when subjected to Congo Red plates. Six bacterial isolates showed the highest
ratio of xylanolyticcellulolytic were screened further by produced using Beech wood xylan as a sole carbon source. Bacterial no 2.1 and 10.1.b pH 7, 60° C and no 7 pH 7, 50° C showed high xylanase
activity than others. Xylanase from three selected bacteria were produced further for 7 days, bacteria no 10.1.b showed highest activity when produced at day two, pH 7 with temperature 60° C. The acquired
bacteria expected to be used in conversion process of paper pulp into dissolving pulp that appropriate with commercial standard.
Keywords: xylanase, xylanolitic bacteria, hot spring sediments, ratio of xylanolyticcellulolytic
Introduction
Cellulose is one source of renewable material that can be used to produce some derivatives such as esters and ethers. One of the cellulose derivate is dissolving pulp that can be used to produce regenerated
cellulose and cellulose derivatives with high purity and high reactivity. Two main processes in dissolving pulp productions are acid sulite and pre-hydrolysis kraft. Total production of dissolving pulp using acid
sulite process is about 65 from total production; meanwhile other process contributes about 25 Sixta, 2006. Dissolving pulp is highly pure pulp that exhibit higher cellulose content over 90
and low level of hemicelluloses, lignin, and extractives 10 with the cellulose reactivity 65 for hardwood and 75 for softwood, level uniformity of the molecular weight, high brightness, and a
viscosity between 200-300 dm
3
kg Köpcke et al., 2010, Li et al., 2012. Production of dissolving pulp present higher cost than paper-grades pulps because of the wood costs
production of dissolving pulp has a lower yield because in its process hemicellulose is dissolved and washed away, capital costs, chemicals costs, production rate and inventories and storage spaces Hillman,
2006. Therefore, an alternative production technology such as converting or upgrading paper-grades pulps into dissolving pulp is a very interesting topic lately. The major problem in this converting process
is paper-grades pulp contains lower cellulose content and higher hemicellulose content Köpcke, 2010. Therefore, removing hemicellulose from the paper-grades pulp is crucial. High amount of hemicellulose
10 are undesirable impurities because they can effect the ilterability, xanthation and strength of the end product Christov and Prior, 1993.
Methods for removing hemicelluloses can be done by using enzymatic process, chemical process alkaline extraction step or by combining these two processes. Alkaline extraction using alkaline
solution is well known as an effective method to remove the hemicellulose; this process is cheap, has shorter reaction times, easier to perform and handles in large scales but in the other side this chemical
also degrades cellulose and impacts its reactivity. Meanwhile, enzyme technology is less effective comparing with alkaline extraction step Köpcke et al., 2010. And also, using enzyme in the manufacture
of dissolving pulp requires longer reaction times and required more controlled system. However, this technology showing other advantages such as higher selectivity, more environmentally friendly
Enzymatic depolymerization of hemicellulose to monomer sugars needs synergistic action of multiple enzymes. One of the enzymes is endo-xylanases EC. 3.2.1.8, this enzyme play crucial role
in xylan degradation. This enzyme catalyzes endohydrolysis of 1, 4-β-xylosidic linkages into short
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oligosaccharides Biely et al., 1985. The use of this enzyme in paper-grades pulp conversion has been limited by lack of enzyme active at neutral to alkaline pH and elevated temperature. Considering the
industrial xylanase in the process of dissolving pulp manufacturing process, the aim of this study is isolation of xylanolitic bacteria from hot spring sediments. Hot spring habitat is selected because is
the natural sink of thermophilic microorganism, which hopefully can provide thermo active enzymes Bhagat et al., 2014.
Experimental Materials
The media and chemicals used in the experiment were the basic ingredients for microbial cultures and analytical grades. All the materials were purchased from Merck, Sigma-Aldrich, Serva and Oxoid.
Nutrient medium Nakamura medium with modiication were used for screening of bacteria, bacterial activation and production of enzymes, containing g 100 mL: Beech wood xylan Serva 0.5 wv,
peptone 0.5 wv, yeast extract 0.5 wv, K
2
HPO
4
0.1 wv, MgSO
4
.7H
2
O 0.02 wv and 100 mL of distilled water Nakamura et al., 1993. pH of the medium was adjusted to initial pH 7 by 5
acetic acid vv and to pH 8 with addition of Na
2
CO
3
0.05 wv.
Sample Collection and Isolation of Thermophilic Bacteria Sample Collection
Hot spring sediment samples were collected from Kamojang hot spring, Pokja Wisata Kamojang Hijau, Kompleks PLN Kamojang Desa Laksana,Kecamatan Ibun, Garut. Samples were taken randomly,
collected in sterile bottles, labeled, transported on ice and stored at 4 °C until analyses. The temperature of hot water was 79 - 81°C with pH ± 4 – 5, respectively.
Bacterial Enrichment, Isolation and Culture Maintenance
10 mL of sediment samples were inoculated using 50 mL of nutrient broth NB medium then incubated in the orbital shaker at 70°C, with shaking 110 rpm for 24 h. This enrichment procedure was
conducted for 5 times until the bacterial suspensions able to growth well in the medium. The suspensions then were used as a source for bacterial isolation. Standard serial dilution method using Nutrient Agar
NA medium was used to isolate the thermophilic bacteria. The suspension were spread on the agar medium, and then incubated at 50°C and 60°C in a bench top incubator for 24 to 48 h. To obtained pure
culture, distinctive colonies from agar plates were pick up and transferred to fresh agar plate using four
way streaks methods then incubated at 50°C and 60°C for 24 to 48 h, this puriication step was repeated two times. The pure cultures were maintained in NA slant then keep it at 4°C.
Screening of Xylanase-Producing Bacteria Qualitative Assay
The strains were initially screened for xylanase activity using modiied Nakamura medium Nakamura et al., 1993 pH 7 and 8 containing 0.5 wv Beech wood xylan as a sole of carbon source. Beside that,
cellulase activity was screened using CMC Carboxyl Methyl Cellulose as a carbon source. Xylanase and cellulose producing bacteria were selected using Theather and Wood method 1982. The bacteria
that already growths for 48 h were looded with 0.5 wv Congo red for 15 min followed by repeated washing with 1M NaCl wv for zone analysis Cordeiro et al., 2002. Positive xylanase activity was
detected by the presence of yellow halo zone against red background.
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Quantitative Assay
Selected bacterial isolates were quantitatively assayed by growing them in modiied Nakamura medium supplemented with 0.5 wv Beech wood xylan. Bacterial inoculum 10 , vv was
inoculated then incubated under shaking conditions 130 rpm at pH 7 and 8 with temperature 50°C or 60°C. After 72 h, all the fermented broth was harvested, centrifuged to separate the supernatant and
cell pellet then the cell free supernatant crude extract was preserved using NaN
3
0.02 and used for xylanase activity assay.
Bacterial Growth and Xylanase Production Pattern
To obtain bacterial growth and xylanase production pattern, selected bacteria was inoculated in the culture broth with Beech wood xylan as a sole carbon source. Bacterial suspension was incubated under
shaking conditions 130 rpm at 50°C and 60°C for 7 days. Number of bacterial cell and xylanase activity were assayed at regular intervals of 24 hours by measuring the bacterial cell using CFU methods
and reducing sugars using Dinitro Salicylic Acid DNSA respectively.
Xylanase Assays
Xylanase activity was assayed according to Bailey et al. 1992 methods using DNSA method. The concentration of reducing sugars was measured as xylose equivalent at 520 nm. One unit U xylanase
activity is deined as the amount of enzymes that produce 1 µmol xylose per minute under experimental condition. The enzyme activities were conducted in triplicate n = 3.
Results and Discussions Isolation and Screening of Xylanase-Producing Bacteria
Hot springs are interesting environments from which bacteria having thermotolerant enzymes can be isolated. There are 10 isolates 50°C and 21 isolates 60°C were obtained during the
bacterial isolation step from hot spring sediments sample Fig. 1. These isolates were selected according to differences in their colony morphology. All the bacteria were evaluated for xylanase production. A
total of 10 50°C and 21 isolates 60°C showed yellow halo zone against red background, showing its ability to produce extracellular xylanase when subjected on xylan medium as a sole carbon source along
with other components at pH 7 and pH 8. Xylanolitic bacteria were selected based on xylanolytic index of xylan hydrolysis after 48 h. All bacteria that were able to produce xylanase then further screened by
growing the bacteria in a medium containing CMC, to ind out which bacteria were able to produce high xylanase with low cellulase.
Fig. 1. Bacterial isolates from sediment hot spring A 50°C B 60°C Bacteria that can produce cellulase was characterized by the formation of yellow zones with a red
background around bacterial colonies. To ind out the bacteria with the highest xylanase activity and lowest cellulase activity, ratio of xylanolytic against cellulolytic was calculated. Based on the calculation
A B
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results, six bacterial isolates i.e no 5, 6b and 7 from 50°C and no 2.1; 3.1.b and 10.1.b from 60°C were selected for further studies Table 1.
Table 1. Qualitative screening result of six xylanase producing bacteria after incubated at pH 7 and 8 with temperature 50°C and 60°C for 48 h
No Xylanolytic Index
Cellulolytic index Ratio
pH pH
pH 7
8 7
8 7
8 5
0.83 1.06
0.50 0.63
1.67 1.68
6b 0.74
0.85 0.00
0.60 -
1.42 7
0.75 0.81
0.00 0.73
- 1.11
2.1 0.93
1.06 0.79
0.48 1.18
2.22 3.1b
0.86 0.92
0.72 0.55
1.20 1.68
10.1b 0.88
0.97 0.63
0.75 1.39
1.30
- Xylanolytic and cellulolytic index is calculated based on ratio of diameter of clear zone divided by diameter of colony - Ratio = xylanolytic index cellulolytic index
These six bacterial isolates which were able to produce xylanase with lowest cellulase then evaluated for xylanase production in shaking liquid xylan medium for 72 hours. Results showed that almost all the
bacteria were able to produce xylanase when produced at pH 7 and 8 except isolate no 6 and 2.1 Fig 2.. Three bacterial isolates that showed highest activity isolates no 7, 2.1 and 10.1.b was selected for further
experiment. This results can not be used to determine which bacteria are best for xylanase production yet, therefore time course of bacterial growth and xylanase production pattern need to performed.
Bacterial Growth and Xylanase Production Pattern
This experiment was conducted by producing xylanase for 7 days using beech wood xylan as a sole carbon source. Addition of xylan into liquid medium is important because xylanase production need
inducers such as xylan or other hemicellulose material Kulkarni et al., 1999; Tseng et al., 2002. The growth of bacteria and xylanase assay were performed once per 24 h for 7 consecutive days Fig 3.. The
time course of growth for three bacteria followed similar pattern, it showed that the exponensial phase was obtained until day 1 then enter to stationary phase until the end of observation day.
0.002 0.004
0.006 0.008
0.01 0.012
5 6b
7 2.1
3.1.b 10.1.b
50°C 60°C
E n
z y
m e
a c
ti v
it y
U m
L
Isolates code, temperature
pH 7 pH 8
Fig. 2. The result of xylanase activity of crude extract from bacterial isolates isolated at 50°C and 60°C
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Activity Assay Condition: Phosphate Buffer 25 mM, pH 7 at 50°C
The production of extracellular xylanase by three bacterial isolates followed different pattern. The growth and production of extracellular xylanase for isolate no 7 showed that xylanase production started
at the end of logaritmic phase day 1, then stopped at day 2 and 3 Fig 3A.. The xylanase production increased signiicantly on day 4 at late stationary phase, then decreasing with increased of incubation
time. Moreover, based on xylanase production pattern, two peaks of xylanase activity were found on days 1 and 4, the existence of these two peaks may occur because of the de-novo synthesis of enzymes
that are necessary for xylan hydrolysis Heck et al., 2002.
Different xylanase production pattern showed when isolate no 2.1 were grown in the liquid xylan medium, the formation of xylanase started from day 2 and reached a maxiumum at day 3 Fig 3B..
Xylanase was produced during the stationary phase. Meanwhile, xylanase production was observed at day 1 when isolate no 10.1.b is grown on xylan medium Fig 3C.. Xylanase activity increaced
signiicantly at day 2 then decreased until the end of fermentation. Xylanase is produced in the middle of logaritmic phase, initial and at the end of stationary phase. An increase in xylanase activity during
later stage of growth might be due to the release of small amount of xylanase from the aged cell entering into autolysis Cordeiro et al., 2002. Based on three bacterial growth and xylanase production curve,
xylanase production were not stable, probably caused by degradation of xylan polymer into smaller
oligosaccharides by β-xylosidase which inhibit endoxylanase activity Tuncer, 2000. Kulkarni et al. 1999 stated high concentration of xylooligosaccharides in the medium is able to repress the biosynthesis
of endoxylanase. Thus, based on the three curve obtained can be concluded that isolate no 10.1.b was selected and will be used further for xylanase production. Xylanase production time is 48 h with initial
medium pH 7 at 60°C during initial stationary phase.
0.000 0.001
0.002 0.003
0.004 0.005
0.00 1.50
3.00 4.50
6.00 7.50
9.00
1 2
3 4
5 6
7
E n
z y
m e
a c
ti v
it y
U m
L
N u
m b
e r
o f c
e ll
s L
o g
Time day
Number of cells Xylanase activity
A B
0.00 0.01
0.02 0.03
0.04 0.05
0.00 1.50
3.00 4.50
6.00 7.50
9.00
1 2
3 4
5 6
7
A c
ti v
it y
a ss
a y
U m
L
N u
m b
e r
o f c
e ll
s L
o g
Time Day
Number of cells Enzyme activity
C Fig. 3. Bacterial growth and xylanase production pattern of bacterial isolate no 7 A, no 2.1 B and 10.1.b C
• The crude extract for isolate no 7 is produced using xylan medium pH 7, incubated at 50°C for seven days
• The crude extract for isolate no 2.1 and 10.1.are produced using xylan medium pH 7, incubated at 60°C for seven days
• Activity assay condition: phosphate buffer 25 mM, pH 7 at 50°C
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Conclusion
Xylanolytic producing bacteria was isolated and screened from geothermal spring sediments. 21 bacteria at 60° C and 10 bacteria at 50° C have been isolated and gave positive result when subjected to
Congo Red plates. Six bacterial isolates which showed the highest ratio xylanolytic cellulolytic were observed further by produced it using liquid Beech wood xylan medium pH 7. Bacterial isolates no 2.1
and 10.1.b 60° C and no 7 50° C showed high xylanase activity than others. Bacterial growth and xylanase production pattern was conducted for 7 days for each isolate, bacterial isolate no 10.1.b showed
highest activity when produced at day two, pH 7 with temperature 60° C. The obtained bacteria need to
identiied further, while the produced enzymes needs to characterized to know its ability. Hopefully this bacterial isolates can be used in coverting paper-grades pulp into dissolving pulp.
Acknowledgements
We would like to acknowledge to all technicians in Center for Pulp and Paper, internship students that already helped us conducting this experiment. The inancial support is funded by government fund 2016.
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