ISBN : 978-602-17761-0-0
205
© 2013 Published by Center for Pulp and Paper through REPTech2012
Xylanase, An Environmentally Friendly Bleaching Agent for Pulp and Paper: Characterization and Stability Study of Bacillus halodurans CM1 Crude Xylanase
Nuur Faridatun Hasanah, Dian Fajar Vitia Ningrum, Budiasih Wahyuntari
1
Center for Bioindustrial Technology, Laboratoriesfor Technology Development of Agro-Biomedical Industries, LAPTIAB- BPPT, Puspiptek-Serpong 611, Tangerang Selatan 15314, Indonesia
1
budiasih.wahyuntaribppt.go.id,
1
solichin.budiasihgmail.com
ABSTRACT
Thermoalkalophilic xylanases have many important applications especially in the pulp and paper industry. Bacillus halodurans CM1 a thermoalkalophilic bacterium recently has been isolated from sediment of Cimangguhot
spring, West Java. The isolate produced extracellular xylanase. The experiment observed the effect of pH and fermentation time on xylanase production and partial characterization of the enzyme that related to the enzyme
application as bleaching agent in pulp and paper processing. The highest production of xylanase was observed at pH 10 and temperature 55
o
C after 21 hours of fermentation. The optimal xylanase activity was at pH 7.0 and 70
o
C. The molecular weight of the enzyme was approximately 27.67 kDa. The enzyme hydrolyzed xylan into xylobiose,
xylotriose and other longer xylooligosaccharides. Stability study was conducted at pH 7.0 – 9.0 and temperature 60- 80ºC. The stability study showed that the enzyme only stable at pH 7 and 60
o
C, which retained 60 of its activity after 105 minutes, therefore the enzyme might be used for biobleaching of kraft pulp and deinking of used
paper. Keywords: Bacillus halodurans, xylanase enzyme, thermoalkalophilic bacterium
1. Introduction
Xylan is a major component of plant cell wall hemicellulose. The major constituents of
hemicelluloses are the hetero-1,4-β-D-Xylan and hetero-1,4-β-D-Mannans. Xylanis present
predominantly in hard wood and graminaceous plant. For complete hydrolysis of xylan, many
xylanolytic microorganisms often synthesize the multiple groups of xylanolytic enzymes [13].
Interest in the application of xylanases in the pulp and paper industry has increased during
recent years. Xylanases may be used in pulp- prebleaching process to remove the hemicelluloses
which bind to the pulp. The hydrolysis of pulp- bound hemicelluloses releases the lignin in the
pulp, reducing the amount of chlorine required for conventional chemical bleaching and minimizing
the toxic [13].The removal of lignin is essentially required during paper manufacturing. In some
study, mix enzyme preparation having both xylanase and laccase activity can be used for
biobleaching at 55
o
C, pH 9 [3, 7]. However, most of the xylanases known to date are optimally active
at temperatures below 50ºC and are active in acidic or neutral pH. Conversely, only a few xylanases
are reported to be active and stable at alkaline pH and high temperature [20, 22, 26].In this study, we
reported characterization of the enzyme produced by a newly isolated bacterium, including effect of
pH and temperature on xylanase activity, stability, and molecular weight of the enzyme.
2. Materials and Methods 2.1. Microorganism and Effect of pH and
Fermentation Time on Enzyme Production Bacillus halodurans CM1 culture collection of
Bioindustry Laboratory, BPPT was refreshed at 55
o
C in modiied Luria Broth medium containing 0.5
wv bacto peptone, 0.25 wv yeast extract, 0.25 wv sodium chloride and 1 wv xylan as a
substrate. The culture of Bacillus halodurans CM1 was fermented at 55
o
C for 24 h in the modiied Nakamura et al 1994 medium using 1 wv xylan as a substrate
at different pHs pH 8; 9; 10 11. The composition of modiied Nakamura et al 1994 was as follows: 0.25
wv bactopeptone, 0.25 wv yeast extract, 0.05 wv K
2
HPO
4
.3H
2
O, 0.01 wv MgSO
4
.7H
2
O and 1 wv beechwoodxylan Sigma Aldrich Co,
St. Louis, MO [14]. After 20 hours of fermentation, the sample was taken for measuring the activity and
protein content of the cells free supernatant. The cells were removed from fermented broth by centrifugation
at 5600 x g using High-Speed Refrigerated Centrifuge Himac CR 21G and R10A3 rotor for 15 min at 4
o
C and the supernatant from extracellular secretion was used
for characterization of the enzyme.
2.2. Effect of Temperature and pH on Enzyme Activity
The inluence of pHs on xylanase activities were measured at 50°C fermentation temperature at pHs
206
© 2013 Published by Center for Pulp and Paper through REPTech2012
ranging from 7.0 to 11.0 buffer used at pH 7 8 was sodium phosphate, pH 9 was Tris HCL, pH 10 11
was glycine-NaOH. The inluence of temperature on enzyme activity
was determined by incubating the enzyme at optimum pH resulted from previous study at temperatures
ranging from 60-100
o
C.
2.3. Enzyme Activity and Protein Concentration
Xylanase activity was assayed using Dinitrosalicylic Acid DNS method, according to Bailey et al.
1992 [2]. Beechwoodxylan was suspended in 50 mM sodium phosphate buffer pH 7.0. The reaction
mixture contained 50 µL of crude enzyme and 450 µL of 1 wv xylan was incubated for 5 min in
the thermomixer at the optimum temperature for enzyme activity. The reaction was terminated by the
addition of 750 µL of DNS reagent. The mixture was centrifuged at 14.000 rpm using Centrifuges MiniSpin
plus from Eppendorf for 2 min and the supernatant was heated at 100
o
C for 5 min. The mixture was cooled in running water, and then added 250 µL of distilled
water. Reducing sugar released during incubation was measured as xylose equivalents at l540 nm. One unit
xylanase activity is deined as the amount of enzyme required to liberate 1 µmol of xylose per minute at the
assay condition [23, 24]. Protein concentration was determined by Bio-Rad
Protein Assay, based on the method of Bradford 1976 with Bovine Serum Albumin BSA as a standard
protein[7].
2.4. Stability of Enzyme
The pH of crude enzyme was adjusted at pH7.0; 8.0 9.0, then the reaction mixture was incubated
in different temperature 60, 70 80
o
C for 120 min. Residual activity was observed every 15 minutes.
2.5. Electrophoresis
The molecular weight of the crude xylanase was estimated by sodium dodecyl sulphate-polyacrylamide
gel electrophoresis in 12 vv acrylamide gel using low molecular weight markers Amersham
Low Molecular Weight Calibration Kit for SDS Electrophoresis. A suspension of beechwoodxylan
at a inal concentration 0.1 wv was incorporated into the separating gel before addition of ammonium
persulphate. Proteins were visualized by silver staining with silver nitrate solution.
2.6. Zymogram Analysis
After completing electrophoresis the enzyme, the gels were washed in 2.5 vv Triton X-100 for 60
min and then incubated at 70
o
C for 15 min in 50 mM sodium phosphate buffer pH 7.0. The reaction was
stopped by immersing the gels at 4
o
C for 15 min. The gel was then incubated in 0.1 congo red solution
for 20 min at room temperature with gentle shaking and destaining was accomplished by washing the gel
with 1 M NaCl until the active bands appeared clearly that indicating the bands was the active xylanolytic
enzymes. The addition of 1 N HCl caused the background to turn dark blue, emphasizing the active
bands [22].
Hydrolysis Product of Xylanase
The hydrolysis of xylan using beechwood xylan 1. The crude enzyme was mixed with 1 wv
beechwoodxylan 1:1 then incubated for 3 hours in the thermomixer at the optimum temperature for
enzyme activity 70
o
C. Hydrolysis products were detected by Thin Layer Chromatography TLC
which performed on Merck TLC plate of silica gel 60 F
254
Merck, Darmstadt, Germany. Concentrated sample was applied onto TLC plates. The solvent
system was 1-butanol-acetic acid-water 2:1:1, vvv. The products on the plate were detected by
heating at 50
o
C for a few minutes in a hot-dry oven after spraying with a mixture of 4 ml aniline-4 gr
α-diphenilamine-20 ml acetone. The standard used were xylose, xylobiose, xylotriose, xylotetraose,
xylopentaose and xylohexaose [20].
3. Results 3.1. Effect of pH and Fermentation Time on
Enzyme Production The effect of pHs and fermentation time on
xylanase production and protein concentration of the enzyme were shown in Fig 1 and Fig 2. Fermentation
condition which gave the highest production of extracellular xylanase was at pH 10 after 21 hours of
fermentation.
Fig 1. Xylanase Activity During Fermentation at Different pH
ISBN : 978-602-17761-0-0
207
© 2013 Published by Center for Pulp and Paper through REPTech2012
Fig 2. Protein Concentration During Fermentation at Different pH
3.2. Effect of pH and Temperature on xylanase activity
Experimental results of the inluence of various pHs and temperatures were shown in Fig.3. The
optimum activity of xylanase was observed at pH 7 and 70
o
C.
Fig 3. Effect of Temperature and pH of Xylanase Activity at Different pH
3.3. Effect of Temperature and pH on Enzyme Stability
Thermal and pH stability of the enzyme was observed in the absence of substrate at various
temperatures and pHs. The experimental results were shown in Fig 4 and Fig 5. Fig 4presentsthe relative
residual activity, whereas Fig 5 presentage actual activity of the enzyme. The enzyme was the most
stable at pH 7 and 60°C. After incubating the enzyme at pH 7 and 60°C for 105 minutes the remaining
activity was still 209 Uml 60.
Fig. 5. Stability of Xylanase Enzyme at Different pH and Temperature
Fig 6. Stability of Xylanase Enzyme at Various pHs and Temperatures
3.4.Electroforesis and Zymogram
Electrophoretic studies of the xylanase crude extracts using SDSPAGE and zymograms showed
the presence of multiple protein bands. The molecular weight of the enzyme was approximately 27.67 kDa.
3.5. Thin Layer Chromatography TLC
Thin Layer Chromatography was showed that the xylanase hydrolysed xylan into xylobiose, xylotriose,
xylotetraose and xylopentaose Fig. 7.
208
© 2013 Published by Center for Pulp and Paper through REPTech2012
Fig. 7. Thin Layer Chromatogram of Xylan Hydrolyzed by The XylanaseE-7 : Xylanase
Product at pH 7; E-9 : Xylanase Product at pH 9, S: Xylooligosaccharide Standards: X1: Xylose; X2:
Xylobiose; X3: Xylotriose; X4: Xylotetraose; X5: Xylopentaose; X6: Xylohexaose.
Discussion
Based on experimental data, B. halodurans CM1 produced extracellular thermophilic xylanolytic
enzyme. The optimal production of the enzyme was at 55
o
C, pH 10 after 21 hours fermentation with 100rpm agitation. The optimum activity of the enzyme was
observed at pH 7, 70
o
C. Some research has been reported that the activity of xylanolytic enzyme
ranging from pH 5-10, with the optimum temperature range 50-75
o
C depending on the species.The optimum activity of Bacillus sp. AQ-1 was at pH 7, 60
o
C [18], Bacillus licheniformis I-5 at pH 7, 50
o
C [26], Bacillus sp. NCIM 59 at pH 6 to 7.5, 25
o
C [16], Bacillusspat pH 7, 55
o
C [28], Bacillussp JB99 at pH 10, 45
o
C [13]. As shown in Fig. 3, the xylanolytic enzyme
produced by B. halodurans CM1 was optimally active at pH 7, 70
o
C. Similar results were observed that optimal temperature of xylanase produced by Bacillus
sp TAR-1 was at 75
o
C at pH 7 and 70
o
C at pH 9.0 [14]. Based on the experimental results xylanase used in this
study was a thermophilic xylanolytic enzyme which might have potential for pulp bio-bleaching
p
rocesses. This data is also supported by the stability of enzymes
which stable at pH 7 and temperature 60
o
C. The study shows that after incubating the enzyme at pH 7 and 60°C
for 105 minutes the remaining activity was still 209 Uml 60. The optimal temperature and stability of
this enzyme are comparable to thermostable xylanase produced extracellularly by Bacillus thermoleovoran
K-3d dan
B. lavothermus LB3A that has been reported stable for 2 hours at pH 7, temperature 70
o
C [20]. The other study reported that the xylanolitic enzyme
from thermophilic strain Clostridium absonum CFR- 702 was stable up to 60
o
C Xyl-I and 50
o
C Xyl- II [19].In biobleaching process using xylanase, the
most important parameters are enzyme stability at higher pH and temperature. Biobleaching process
using xylanase from Streptomyces thermoviolaceus was optimized and found to be most effective at
65
o
C and pH 6.0, with the crude enzyme preparation blended to a pulp concistency of 5 [9]. The study
of xylanase from Bacillus sp for biobleaching of kraft pulp has been evaluated at 60
o
C at pH 9.0.[1]. Thermoactivecellulase-free xylanase produced from
alkaliphilic Bacillus sp that was stable at 60
o
C for more than 60 minutes was having potential for bio-
bleachingprocess.[1]. Xylanase can also used for deinking process, conditions in a previous research,
the deinking reaction was allowed for 30 minutes at 11 consistensy, pH 7.0 and 50
o
C with continuous slow mixing [17].
The SDS-PAGE and zymogram analysis showed the molecular weight of xylanase was 26,7kDa. In
earlier reports showed that xylanase produced by Bacillus spp JB 99 was 16 kDa [13]. Xylanase which
were produced by Bacillus spp reported having molecular masses ranging between 3600-23,000
Daltons [12]. However, in some cases Bacillus sp with Fig 6. Zymogram and SDSPAGE XylanasefromB. Halodurans CMI.Zym: Zymogram; Marker: Low Molecular
Weight Marker of Protein; E-7: Band of Protein Sample at pH 7; E-9: Band of Protein Sample at pH 9
ISBN : 978-602-17761-0-0
209
© 2013 Published by Center for Pulp and Paper through REPTech2012
high molecular mass of 24000 to 145,000 Dalton was also reported [13].
The products of hydrolysis beechwoodxylan was observed as xylobiose, xylotriose, xylotetraose and
xylopentaose which indicated endoxylanase activity. In this study, the enzyme did not produce xylose which
might be due to less incubationtime. In some study, xylose would be formed after 12 hours incubation,
since the initially xylanase cleaved the substrate to liberate xylooligosaccharides and then the resulting
oligosaccharides were probably cleaved to form xylose [11].
Based on this experimental stability data, the xylanase enzyme might be used in pulp and paper
manufacture as an agent for bio-bleaching. The process of lignin removal from chemical pulps to
produced bright or completely white inished pulp is called ‘bleaching’. The most important application of
xylanase enzymes is the prebleaching of kraft pulp. Currently, the most effective application of xylanase
is in prebleaching of kraft pulp to minimize the use
of harsh chemicals in the subsequent treatment stages of kraft pulp. While many applications of enzymes
in paper industries are still in the research and developmental stage, several applications have found
their way into the mills in unprecedented short period of time in the last decade [3]. Several criteria are
essential for choosing a microorganism to produced xylanases. The optimum temperature for xylanase
action ranges between 35 and 60
o
C. In the mills, xylanase pretreatment takes place in the brown stock
high-density storage tanks, in which pulp is present at high temperature approximately 60
o
C and at alkaline pH. Therefore, xylanases that are active and stable at
high temperature and alkaline pH are desirable [6]. Most of the beneicial effects of xylanase prebleaching
can be obtained after only 1-2 hours of treatment [5, 10].
References
[1] Azeri C, Tamer AU, Oskay M. ThermoactiveCellulase-free Xylanase Production
from Alkaliphilic Bacillus strains Using Various Agro-residues and their Potential in Biobleaching
of Kraf Pulp. Aican Journal of Biotechnology 2010; Vol. 9 1, pp. 063-072.
[2] Bailey MJ, Biely P, Poutanen K. Interlaboratory Testing of Methods for Assay of Xylanase
Activity. J. Biotechnol 1992; 23:257-270. [3] Bajpai P. Application of enzymes in the Pulp and
Paper Industry. Biotechnol Prog 1999; 15:147- 157.
[4] Barreca AM, Fabbrini M, Galli C, Gentili P, Ljunggren S. LaccaseMediated Oxidation of
a Lignin Model for Improved Deligniication Procedures. Journal of Molecular Catalysis B,
Enzymatic 2003; 26, 105-110. [5] Beg QK, Bhushan B, Kapoor M, Hoondal GS.
Enhanced Production of a ThermostableXylanase from Streptomyces sp. QG-11-3 and its Application
in Biobleaching of Eucalyptus Kraft Pulp. Enzyme Microb Technol 2000c; 27:459-466.
[6] Beg QK, Kapoor M, Mahajan L, Hoondal GS. Microbial Xylanases and Their Industrial
Applications: a Review. Appl Microbiol Biotechnol 2001; 56:326-338.
[7] Bradford M.A Rapid and Sensitive Method for the Quantitaion of Microgram Quantities of Protein
Utilizing The Principle of Protein-Dye Binding. Journal of Analytical Biochemistry 1976; 72:255-
260.
[8] Dwivedi P, Vivekanand V, Pareek , Sharma A, Singh RP. Bleach Enhancement of Mixed Wood
Pulp by Xylanase-Laccase Concoction Derived Through Co-culture Strategy. Appl Biochem
Biotechnol 2010; 160:255-268.
[9] Garg AP, McCarthy AJ, Roberts JC. Biobleaching Effect of Streptomyces thermoviolaceus Xylanase
Preparations on Birchwood Kraft Pulp. Enzyme and Microbial Technology by Elsevier Science
1996; 18:261-267.
[10] Gupta S, Bhusnan B, Hoondal GS. Isolation, Puriication and Characterization of Xylanase
from Staphylococcus sp. SG-13 and its Application in Biobleaching of Kraft Pulp. J Appl
Microbiol 2000; 88:325-334.
[11] Kandheparkar R, Bhosle NB. Puriication and
Characterization of Thermoalkalophilic Xylanase Isolated from the Enterobactersp MTCC 5112.
National Institute of Oceanography, India.
[12] Kitamoto N, Yoshino S, Ohmiya K, Tsukagoshi N. Puriication and Characterization of Over
expressed Aspergillus oryzae Xylanase. XynF1. Bioschi Biotechnol Biochem 1999; 63: 1791-94.
[13] Kumar SS, Panday DD, Nalk GR. Puriication
and Molecular Characterization of Low Molecular Weight Cellulase-Free Xylanase from
Thermoalkalophilic Bacillus spp. JB 99. World Journal of Science and Technology 2011; 12:
09-16.
[14] Nakamura S, Ishiguro Y, Nakai R, Wakabayashi K, Aono R, Horikoshi K. Thermophilic Alkaline
Xylanase from Newly Isolated Alkaliphilic and Thermophilic Bacillus sp. Strain TAR-1. Biosci
Biotechnol Biochem1994; 58:78-81.
[15] Nakamura S, Ishiguro Y, Nakai R, Wakabayashi K, Aono R, Horikoshi K. Puriication and
Characterization of AThermopilic Alkaline Xylanase from Thermoalkaliphilic Bacillus sp.
Strain TAR-1. Journal of Moleculer catalysis- Elsevier 1995; 17-15.
[16] Nath D, Rao M. pH Dependent Conformational and Structural Change of Xylanase from an
Alkalophilic Bacillus sp NCIM 59. Enzyme and Microbiol Technology 2001; 28:397-403.
210
© 2013 Published by Center for Pulp and Paper through REPTech2012
[17] Pala H, Mota M, Gama FM. Factors Inluencing
MOW Deinking : Laboratory Scale Studies. Enzyme and Microbial Technology 2006; 38, 81-
87.
[18] Rahayu P, Setyahadi S, Harmita. Production and Puriication of Xylanase From Indonesian Isolate
Bacillus sp. AQ-1 Grown on Bunch Palm Oil. Journal Microbiologi 2008; Volume 3, Number 1,
p 23-26.
[19] Rani DS, Nand K. Puriication and Characterization
of Xylanolytic Enzymes of a Cellulase-free Thermophilic Strain of Clostridium absornum
CFR-702. Anaerob 2001; 7, 45-53.
[20] Ratanakhanokchai K, Kyu KI, TanticharoenM. Puriication and Properties of a Xylan-Binding
Endoxylanase from Alkalophilic Bacillus sp. Strain K-1. Appl Environ Microbiol 1999;
65:694-697.
[21] Ryan SE, Nolan K, Thompson R, Gubitz GM, Savage AV, Tuohy MG. Puriication and
Characterization of a New Low Molecular Weight Endoxylanase from Penicillium capsulate.
Enzyme Microb. Technol 2003; 33:775–785.
[22] Sunna A, Prowse SG, Stoffregen F, Antranikian G. Charaterization of the xylanases from the
new isolated thermophilic xylan-degrading Bacillus termoloevorans strain K-3d and Bacillus
thermoleovorans strain K-3d and Bacillus
lavothermus strain LB31. FEMS Microbiol 1997 a; Lett 148-209-16.
[23] Takahashi H, Nakai R, Nakamura S. Puriication
and partial characterization of a basic xylanase produced by thermoalkalophilic Bacillus sp
Strain TAR-1. Bioschi Biotechnol Biochem 2000; 64:887-90.
[24] Tanaka H, Nakamura T, Hayashi S, Ohta K. Puriication and Properties of an extracellular
endo-1,4-b-xylanase from Penicillium citrinum and characterization of the encoding gene. J.
Biosci Bioeng2005; 100:623-30.
[25] Turkiewicz M, Kalinowska H, Zielinska M, Bielecki S. Puriication and characterization of
two endo-1,4- β-xylanases from Antarctic krill,
Euphausiasuperba Dana, Comp. Biochem. Physiol 2000; 127 325–335.
[26] Wahyuntari B, Mangunwardoyo W. Xilanase Pemutih Pulp dan Kertas Ramah Lingkungan :
Karakterisasi dan Stabilisasi Xilanase Bacillus licheniformis I-5. Jurnal Rekayasa Lingkungan
2011; Vol. 7, No. 3, Hal. 205-305.
[27] Wang SL, Yen YH, Shih IL, Chang AC, Chang WT, Wu WC, Chai YD. Production of xylanases
from rice bran by Streptomyces actuosus A-151, Enz. Microb. Technol 2003; In press.
[28] Yang VW, Zhuang Z, Elegir G, Jeffries TW. Alkaline-active Xylanase Produced by an
Alkaliphilic Bacillus sp Isolated from Kraft Pulp. Journal of Industrial Microbiology 1995; 15, 434-
441.
ISBN : 978-602-17761-0-0
211
© 2013 Published by Center for Pulp and Paper through REPTech2012
Optimization of TMP Newsprint Retention System for Retention and Drainage Improvement
Chul-Hun Jung
a
, Jong-Moon Park
b
a
Dept. Forest Product Engineering, Chungbuk National University, Naesudong-ro 52, Cheongju, Chungbuk 361-763, South Korea, 8terra8gmail.com
b
Dept. Forest Product Engineering, Chungbuk National University, Naesudong-ro 52, Cheongju, Chungbuk 361-763, South Korea, jmparkcbu.ac.kr
ABSTRACT
Newsprint stock uses TMP which has wood resin, dissolved and colloidal substances DCS, so they degrade machine runnability, sheet properties, and chemical eficiency. We compared and analyzed two retention
systems, such as PAMBentonite micro particle system and PEOcofactor system. As the TMP ratio rose, PEO cofactor system was more eficient in retention and drainage than the other system. High molecular weight and
non-ionic polymer retention system had less effect on locculation interruption than the traditional electrostatic retention system.
Keywords: newsprint stock, TMP, maicroparticle, PEO, cofactor, retention, drainage
1. Introduction
Recent widely used retention systems are usually based on locculation by polymer charges. Retention
mechanism is affected by the charge conditions. Charge of paper furnish is affected by white-water’s
charge. Therefore, charges of colloidal compounds
and ines in white-water are very important. Especially, performance of polymer is affected by
anionic charge when much of anionic trash and ines exist. Flocculation is induced through electrostatic
locculation of polyelectrolyte, so anionic trash and ines shrink polymers and consequently hinder
retention performance, runnability and quality of product.
Many paper mills try to improve the wastewater closure eficiency and production speed. They also try
to reduce production cost by using more recycled ibers and mechanical pulps. High speed and high anionic
ines content ask well controlled retention system than ever before. They ask more eficient retention system
than normal retention system based on electrostatic locculation mechanism.
Mechanical pulp contains ionic trash like hemicellulose, extractives, lignin, dissolved and
colloidal substance DCS and so on. These substances accumulate at white-water recirculation system
if they are not retained on wire. Consequentially, they deteriorate product quality and runnability,
performance of polymers
[1]
. During mechanical pulping and bleaching, a variety
of wood components are released into the paper mill process water at integrated mill. These components
are called DCS, and they include a wide variety of chemical species including hemicellulose, lipophilic
extractives and lignin-like compound. Because of white water recirculation and reuse, and the fact that
mechanical pulps are generally not washed, DCS can accumulate in the water systems of the pulp and paper
mill. These substances can interfere with papermaking processes by reducing paper quality, degrading paper
machine runnability, and consuming cationic retention aids
[2-6]
. DCS can interfere with the ability of cationic
polymers to reduce iber aggregation in papermaking furnishes. This interference is believed to arise
from interactions between cationic polymers and anionic DCS components leading to formation of
polyelectrolyte complexes
7
. In this work, PEOcofactor system and PAM
bentonite system were compared to apply to TMP and recycled ibers newsprint mills in terms of retention
and drainage.
2. Experimental 2.1 Materials
